clarify to use as the PR branch

This pr is auto merged as it contains a mandatory file and is opened for more than 10 days.

azure-pipelines.yml

@@ -169,6 +169,7 @@ jobs:
   - script: ctest --verbose --timeout 240
     workingDirectory: $(BuildType)
     displayName: CTest
+    
 #  - upload: $(Build.SourcesDirectory)/$(BuildType)
 #    artifact: mimalloc-macos-$(BuildType)
 

cmake/mimalloc-config-version.cmake

@@ -1,5 +1,5 @@
-set(mi_version_major 1)
-set(mi_version_minor 9)
+set(mi_version_major 2)
+set(mi_version_minor 2)
 set(mi_version_patch 3)
 set(mi_version ${mi_version_major}.${mi_version_minor})
 

contrib/vcpkg/portfile.cmake

@@ -5,11 +5,11 @@ vcpkg_from_github(
 
   # The "REF" can be a commit hash, branch name (dev2), or a version (v2.2.1).
   # REF "v${VERSION}"
-  REF 866ce5b89db1dbc3e66bbf89041291fd16329518
+  REF e2db21e9ba9fb9172b7b0aa0fe9b8742525e8774
 
   # The sha512 is the hash of the tar.gz bundle.
   # (To get the sha512, run `vcpkg install mimalloc[override] --overlay-ports=<dir of this file>` and copy the sha from the error message.)
-  SHA512 0b0e5ff823c49b9534b8c32800679806c5d7c29020af058da043c3e6e36ae3c32a1cdd5a21ece97dd60bc7dd4703967f683beac435dbb8514638a6cc55e5dea8
+  SHA512 8cbb601fdf8b46dd6a9c0d314d6da9d4960699853829e96d2470753867f90689fb4caeaf30d628943fd388670dc11902dbecc9cc7c329b99a510524a09bdb612
 )
 
 vcpkg_check_features(OUT_FEATURE_OPTIONS FEATURE_OPTIONS

contrib/vcpkg/vcpkg.json

@@ -1,7 +1,7 @@
 {
   "name": "mimalloc",
-  "version": "1.9.2",
-  "port-version": 2,
+  "version": "2.2.2",
+  "port-version": 1,
   "description": "Compact general purpose allocator with excellent performance",
   "homepage": "https://github.com/microsoft/mimalloc",
   "license": "MIT",

include/mimalloc.h

@@ -1,5 +1,5 @@
 /* ----------------------------------------------------------------------------
-Copyright (c) 2018-2023, Microsoft Research, Daan Leijen
+Copyright (c) 2018-2025, Microsoft Research, Daan Leijen
 This is free software; you can redistribute it and/or modify it under the
 terms of the MIT license. A copy of the license can be found in the file
 "LICENSE" at the root of this distribution.
@@ -8,7 +8,7 @@ terms of the MIT license. A copy of the license can be found in the file
 #ifndef MIMALLOC_H
 #define MIMALLOC_H
 
-#define MI_MALLOC_VERSION 193   // major + 2 digits minor
+#define MI_MALLOC_VERSION 223   // major + 2 digits minor
 
 // ------------------------------------------------------
 // Compiler specific attributes
@@ -97,6 +97,7 @@ terms of the MIT license. A copy of the license can be found in the file
 
 #include <stddef.h>     // size_t
 #include <stdbool.h>    // bool
+#include <stdint.h>     // INTPTR_MAX
 
 #ifdef __cplusplus
 extern "C" {

include/mimalloc/internal.h

@@ -178,10 +178,11 @@ void        _mi_segment_map_freed_at(const mi_segment_t* segment);
 void        _mi_segment_map_unsafe_destroy(void);
 
 // "segment.c"
-mi_page_t*  _mi_segment_page_alloc(mi_heap_t* heap, size_t block_size, size_t page_alignment, mi_segments_tld_t* tld);
-void        _mi_segment_page_free(mi_page_t* page, bool force, mi_segments_tld_t* tld);
-void        _mi_segment_page_abandon(mi_page_t* page, mi_segments_tld_t* tld);
-uint8_t*    _mi_segment_page_start(const mi_segment_t* segment, const mi_page_t* page, size_t* page_size);
+mi_page_t* _mi_segment_page_alloc(mi_heap_t* heap, size_t block_size, size_t page_alignment, mi_segments_tld_t* tld);
+void       _mi_segment_page_free(mi_page_t* page, bool force, mi_segments_tld_t* tld);
+void       _mi_segment_page_abandon(mi_page_t* page, mi_segments_tld_t* tld);
+bool       _mi_segment_try_reclaim_abandoned( mi_heap_t* heap, bool try_all, mi_segments_tld_t* tld);
+void       _mi_segment_collect(mi_segment_t* segment, bool force);
 
 #if MI_HUGE_PAGE_ABANDON
 void        _mi_segment_huge_page_free(mi_segment_t* segment, mi_page_t* page, mi_block_t* block);
@@ -189,10 +190,11 @@ void        _mi_segment_huge_page_free(mi_segment_t* segment, mi_page_t* page, m
 void        _mi_segment_huge_page_reset(mi_segment_t* segment, mi_page_t* page, mi_block_t* block);
 #endif
 
-void        _mi_segments_collect(bool force, mi_segments_tld_t* tld);
-void        _mi_abandoned_reclaim_all(mi_heap_t* heap, mi_segments_tld_t* tld);
-bool        _mi_segment_attempt_reclaim(mi_heap_t* heap, mi_segment_t* segment);
-bool        _mi_segment_visit_blocks(mi_segment_t* segment, int heap_tag, bool visit_blocks, mi_block_visit_fun* visitor, void* arg);
+uint8_t*   _mi_segment_page_start(const mi_segment_t* segment, const mi_page_t* page, size_t* page_size); // page start for any page
+void       _mi_abandoned_reclaim_all(mi_heap_t* heap, mi_segments_tld_t* tld);
+void       _mi_abandoned_collect(mi_heap_t* heap, bool force, mi_segments_tld_t* tld);
+bool       _mi_segment_attempt_reclaim(mi_heap_t* heap, mi_segment_t* segment);
+bool       _mi_segment_visit_blocks(mi_segment_t* segment, int heap_tag, bool visit_blocks, mi_block_visit_fun* visitor, void* arg);
 
 // "page.c"
 void*       _mi_malloc_generic(mi_heap_t* heap, size_t size, bool zero, size_t huge_alignment)  mi_attr_noexcept mi_attr_malloc;
@@ -342,12 +344,28 @@ static inline uintptr_t _mi_align_up(uintptr_t sz, size_t alignment) {
   }
 }
 
+// Align downwards
+static inline uintptr_t _mi_align_down(uintptr_t sz, size_t alignment) {
+  mi_assert_internal(alignment != 0);
+  uintptr_t mask = alignment - 1;
+  if ((alignment & mask) == 0) { // power of two?
+    return (sz & ~mask);
+  }
+  else {
+    return ((sz / alignment) * alignment);
+  }
+}
 
 // Align a pointer upwards
 static inline void* mi_align_up_ptr(void* p, size_t alignment) {
   return (void*)_mi_align_up((uintptr_t)p, alignment);
 }
 
+// Align a pointer downwards
+static inline void* mi_align_down_ptr(void* p, size_t alignment) {
+  return (void*)_mi_align_down((uintptr_t)p, alignment);
+}
+
 
 // Divide upwards: `s <= _mi_divide_up(s,d)*d < s+d`.
 static inline uintptr_t _mi_divide_up(uintptr_t size, size_t divider) {
@@ -371,6 +389,7 @@ static inline bool mi_mem_is_zero(const void* p, size_t size) {
   return true;
 }
 
+
 // Align a byte size to a size in _machine words_,
 // i.e. byte size == `wsize*sizeof(void*)`.
 static inline size_t _mi_wsize_from_size(size_t size) {
@@ -465,29 +484,44 @@ static inline mi_segment_t* _mi_ptr_segment(const void* p) {
   #endif
 }
 
+static inline mi_page_t* mi_slice_to_page(mi_slice_t* s) {
+  mi_assert_internal(s->slice_offset== 0 && s->slice_count > 0);
+  return (mi_page_t*)(s);
+}
+
+static inline mi_slice_t* mi_page_to_slice(mi_page_t* p) {
+  mi_assert_internal(p->slice_offset== 0 && p->slice_count > 0);
+  return (mi_slice_t*)(p);
+}
+
 // Segment belonging to a page
 static inline mi_segment_t* _mi_page_segment(const mi_page_t* page) {
   mi_assert_internal(page!=NULL);
   mi_segment_t* segment = _mi_ptr_segment(page);
-  mi_assert_internal(segment == NULL || page == &segment->pages[page->segment_idx]);
+  mi_assert_internal(segment == NULL || ((mi_slice_t*)page >= segment->slices && (mi_slice_t*)page < segment->slices + segment->slice_entries));
   return segment;
 }
 
-// used internally
-static inline size_t _mi_segment_page_idx_of(const mi_segment_t* segment, const void* p) {
-  // if (segment->page_size > MI_SEGMENT_SIZE) return &segment->pages[0];  // huge pages
-  ptrdiff_t diff = (uint8_t*)p - (uint8_t*)segment;
-  mi_assert_internal(diff >= 0 && (size_t)diff <= MI_SEGMENT_SIZE /* for huge alignment it can be equal */);
-  size_t idx = (size_t)diff >> segment->page_shift;
-  mi_assert_internal(idx < segment->capacity);
-  mi_assert_internal(segment->page_kind <= MI_PAGE_MEDIUM || idx == 0);
-  return idx;
+static inline mi_slice_t* mi_slice_first(const mi_slice_t* slice) {
+  mi_slice_t* start = (mi_slice_t*)((uint8_t*)slice - slice->slice_offset);
+  mi_assert_internal(start >= _mi_ptr_segment(slice)->slices);
+  mi_assert_internal(start->slice_offset == 0);
+  mi_assert_internal(start + start->slice_count > slice);
+  return start;
 }
 
-// Get the page containing the pointer
+// Get the page containing the pointer (performance critical as it is called in mi_free)
 static inline mi_page_t* _mi_segment_page_of(const mi_segment_t* segment, const void* p) {
-  size_t idx = _mi_segment_page_idx_of(segment, p);
-  return &((mi_segment_t*)segment)->pages[idx];
+  mi_assert_internal(p > (void*)segment);
+  ptrdiff_t diff = (uint8_t*)p - (uint8_t*)segment;
+  mi_assert_internal(diff > 0 && diff <= (ptrdiff_t)MI_SEGMENT_SIZE);
+  size_t idx = (size_t)diff >> MI_SEGMENT_SLICE_SHIFT;
+  mi_assert_internal(idx <= segment->slice_entries);
+  mi_slice_t* slice0 = (mi_slice_t*)&segment->slices[idx];
+  mi_slice_t* slice = mi_slice_first(slice0);  // adjust to the block that holds the page data
+  mi_assert_internal(slice->slice_offset == 0);
+  mi_assert_internal(slice >= segment->slices && slice < segment->slices + segment->slice_entries);
+  return mi_slice_to_page(slice);
 }
 
 // Quick page start for initialized pages
@@ -510,8 +544,8 @@ static inline size_t mi_page_block_size(const mi_page_t* page) {
 }
 
 static inline bool mi_page_is_huge(const mi_page_t* page) {
-  mi_assert_internal((page->is_huge && _mi_page_segment(page)->page_kind == MI_PAGE_HUGE) ||
-                     (!page->is_huge && _mi_page_segment(page)->page_kind != MI_PAGE_HUGE));
+  mi_assert_internal((page->is_huge && _mi_page_segment(page)->kind == MI_SEGMENT_HUGE) ||
+                     (!page->is_huge && _mi_page_segment(page)->kind != MI_SEGMENT_HUGE));
   return page->is_huge;
 }
 
@@ -523,7 +557,11 @@ static inline size_t mi_page_usable_block_size(const mi_page_t* page) {
 
 // size of a segment
 static inline size_t mi_segment_size(mi_segment_t* segment) {
-  return segment->segment_size;
+  return segment->segment_slices * MI_SEGMENT_SLICE_SIZE;
+}
+
+static inline uint8_t* mi_segment_end(mi_segment_t* segment) {
+  return (uint8_t*)segment + mi_segment_size(segment);
 }
 
 // Thread free access
@@ -678,12 +716,13 @@ static inline bool mi_is_in_same_segment(const void* p, const void* q) {
 }
 
 static inline bool mi_is_in_same_page(const void* p, const void* q) {
-  mi_segment_t* segmentp = _mi_ptr_segment(p);
-  mi_segment_t* segmentq = _mi_ptr_segment(q);
-  if (segmentp != segmentq) return false;
-  size_t idxp = _mi_segment_page_idx_of(segmentp, p);
-  size_t idxq = _mi_segment_page_idx_of(segmentq, q);
-  return (idxp == idxq);
+  mi_segment_t* segment = _mi_ptr_segment(p);
+  if (_mi_ptr_segment(q) != segment) return false;
+  // assume q may be invalid // return (_mi_segment_page_of(segment, p) == _mi_segment_page_of(segment, q));
+  mi_page_t* page = _mi_segment_page_of(segment, p);
+  size_t psize;
+  uint8_t* start = _mi_segment_page_start(segment, page, &psize);
+  return (start <= (uint8_t*)q && (uint8_t*)q < start + psize);
 }
 
 static inline uintptr_t mi_rotl(uintptr_t x, uintptr_t shift) {
@@ -765,6 +804,50 @@ static inline void mi_block_set_next(const mi_page_t* page, mi_block_t* block, c
 }
 
 
+// -------------------------------------------------------------------
+// commit mask
+// -------------------------------------------------------------------
+
+static inline void mi_commit_mask_create_empty(mi_commit_mask_t* cm) {
+  for (size_t i = 0; i < MI_COMMIT_MASK_FIELD_COUNT; i++) {
+    cm->mask[i] = 0;
+  }
+}
+
+static inline void mi_commit_mask_create_full(mi_commit_mask_t* cm) {
+  for (size_t i = 0; i < MI_COMMIT_MASK_FIELD_COUNT; i++) {
+    cm->mask[i] = ~((size_t)0);
+  }
+}
+
+static inline bool mi_commit_mask_is_empty(const mi_commit_mask_t* cm) {
+  for (size_t i = 0; i < MI_COMMIT_MASK_FIELD_COUNT; i++) {
+    if (cm->mask[i] != 0) return false;
+  }
+  return true;
+}
+
+static inline bool mi_commit_mask_is_full(const mi_commit_mask_t* cm) {
+  for (size_t i = 0; i < MI_COMMIT_MASK_FIELD_COUNT; i++) {
+    if (cm->mask[i] != ~((size_t)0)) return false;
+  }
+  return true;
+}
+
+// defined in `segment.c`:
+size_t _mi_commit_mask_committed_size(const mi_commit_mask_t* cm, size_t total);
+size_t _mi_commit_mask_next_run(const mi_commit_mask_t* cm, size_t* idx);
+
+#define mi_commit_mask_foreach(cm,idx,count) \
+  idx = 0; \
+  while ((count = _mi_commit_mask_next_run(cm,&idx)) > 0) {
+
+#define mi_commit_mask_foreach_end() \
+    idx += count; \
+  }
+
+
+
 /* -----------------------------------------------------------
   memory id's
 ----------------------------------------------------------- */

include/mimalloc/types.h

@@ -13,8 +13,9 @@ terms of the MIT license. A copy of the license can be found in the file
 // mi_heap_t      : all data for a thread-local heap, contains
 //                  lists of all managed heap pages.
 // mi_segment_t   : a larger chunk of memory (32GiB) from where pages
-//                  are allocated.
-// mi_page_t      : a mimalloc page (usually 64KiB or 512KiB) from
+//                  are allocated. A segment is divided in slices (64KiB) from
+//                  which pages are allocated.
+// mi_page_t      : a "mimalloc" page (usually 64KiB or 512KiB) from
 //                  where objects are allocated.
 //                  Note: we write "OS page" for OS memory pages while
 //                  using plain "page" for mimalloc pages (`mi_page_t`).
@@ -167,38 +168,40 @@ typedef int32_t  mi_ssize_t;
 // ------------------------------------------------------
 
 // Main tuning parameters for segment and page sizes
-// Sizes for 64-bit, divide by two for 32-bit
+// Sizes for 64-bit (usually divide by two for 32-bit)
+#ifndef MI_SEGMENT_SLICE_SHIFT
+#define MI_SEGMENT_SLICE_SHIFT            (13 + MI_INTPTR_SHIFT)         // 64KiB  (32KiB on 32-bit)
+#endif
+
+#ifndef MI_SEGMENT_SHIFT
+#if MI_INTPTR_SIZE > 4
+#define MI_SEGMENT_SHIFT                  ( 9 + MI_SEGMENT_SLICE_SHIFT)  // 32MiB
+#else
+#define MI_SEGMENT_SHIFT                  ( 7 + MI_SEGMENT_SLICE_SHIFT)  // 4MiB on 32-bit
+#endif
+#endif
+
 #ifndef MI_SMALL_PAGE_SHIFT
-#define MI_SMALL_PAGE_SHIFT               (13 + MI_INTPTR_SHIFT)      // 64KiB
+#define MI_SMALL_PAGE_SHIFT               (MI_SEGMENT_SLICE_SHIFT)       // 64KiB
 #endif
 #ifndef MI_MEDIUM_PAGE_SHIFT
-#define MI_MEDIUM_PAGE_SHIFT              ( 3 + MI_SMALL_PAGE_SHIFT)  // 512KiB
-#endif
-#ifndef MI_LARGE_PAGE_SHIFT
-#define MI_LARGE_PAGE_SHIFT               ( 3 + MI_MEDIUM_PAGE_SHIFT) // 4MiB
-#endif
-#ifndef MI_SEGMENT_SHIFT
-#define MI_SEGMENT_SHIFT                  ( MI_LARGE_PAGE_SHIFT)      // 4MiB -- must be equal to `MI_LARGE_PAGE_SHIFT`
+#define MI_MEDIUM_PAGE_SHIFT              ( 3 + MI_SMALL_PAGE_SHIFT)     // 512KiB
 #endif
 
 // Derived constants
 #define MI_SEGMENT_SIZE                   (MI_ZU(1)<<MI_SEGMENT_SHIFT)
-#define MI_SEGMENT_ALIGN                  (MI_SEGMENT_SIZE)
+#define MI_SEGMENT_ALIGN                  MI_SEGMENT_SIZE
 #define MI_SEGMENT_MASK                   ((uintptr_t)(MI_SEGMENT_ALIGN - 1))
+#define MI_SEGMENT_SLICE_SIZE             (MI_ZU(1)<< MI_SEGMENT_SLICE_SHIFT)
+#define MI_SLICES_PER_SEGMENT             (MI_SEGMENT_SIZE / MI_SEGMENT_SLICE_SIZE) // 1024
 
 #define MI_SMALL_PAGE_SIZE                (MI_ZU(1)<<MI_SMALL_PAGE_SHIFT)
 #define MI_MEDIUM_PAGE_SIZE               (MI_ZU(1)<<MI_MEDIUM_PAGE_SHIFT)
-#define MI_LARGE_PAGE_SIZE                (MI_ZU(1)<<MI_LARGE_PAGE_SHIFT)
 
-#define MI_SMALL_PAGES_PER_SEGMENT        (MI_SEGMENT_SIZE/MI_SMALL_PAGE_SIZE)
-#define MI_MEDIUM_PAGES_PER_SEGMENT       (MI_SEGMENT_SIZE/MI_MEDIUM_PAGE_SIZE)
-#define MI_LARGE_PAGES_PER_SEGMENT        (MI_SEGMENT_SIZE/MI_LARGE_PAGE_SIZE)
-
-// The max object size are checked to not waste more than 12.5% internally over the page sizes.
-// (Except for large pages since huge objects are allocated in 4MiB chunks)
-#define MI_SMALL_OBJ_SIZE_MAX             (MI_SMALL_PAGE_SIZE/8)   // 8 KiB
-#define MI_MEDIUM_OBJ_SIZE_MAX            (MI_MEDIUM_PAGE_SIZE/8)  // 64 KiB
-#define MI_LARGE_OBJ_SIZE_MAX             (MI_LARGE_PAGE_SIZE/4)   // 1 MiB
+#define MI_SMALL_OBJ_SIZE_MAX             (MI_SMALL_PAGE_SIZE/8)   // 8 KiB on 64-bit
+#define MI_MEDIUM_OBJ_SIZE_MAX            (MI_MEDIUM_PAGE_SIZE/8)  // 64 KiB on 64-bit
+#define MI_MEDIUM_OBJ_WSIZE_MAX           (MI_MEDIUM_OBJ_SIZE_MAX/MI_INTPTR_SIZE)
+#define MI_LARGE_OBJ_SIZE_MAX             (MI_SEGMENT_SIZE/2)      // 16 MiB on 64-bit
 #define MI_LARGE_OBJ_WSIZE_MAX            (MI_LARGE_OBJ_SIZE_MAX/MI_INTPTR_SIZE)
 
 // Maximum number of size classes. (spaced exponentially in 12.5% increments)
@@ -206,18 +209,27 @@ typedef int32_t  mi_ssize_t;
 #error "mimalloc internal: expecting 73 bins"
 #endif
 
-#if (MI_LARGE_OBJ_WSIZE_MAX >= 655360)
+#if (MI_MEDIUM_OBJ_WSIZE_MAX >= 655360)
 #error "mimalloc internal: define more bins"
 #endif
 
 // Maximum block size for which blocks are guaranteed to be block size aligned. (see `segment.c:_mi_segment_page_start`)
-#define MI_MAX_ALIGN_GUARANTEE   (MI_MEDIUM_OBJ_SIZE_MAX)
+#define MI_MAX_ALIGN_GUARANTEE            (MI_MEDIUM_OBJ_SIZE_MAX)
 
 // Alignments over MI_BLOCK_ALIGNMENT_MAX are allocated in dedicated huge page segments
-#define MI_BLOCK_ALIGNMENT_MAX   (MI_SEGMENT_SIZE >> 1)
+#define MI_BLOCK_ALIGNMENT_MAX            (MI_SEGMENT_SIZE >> 1)
 
-// We never allocate more than PTRDIFF_MAX (see also <https://sourceware.org/ml/libc-announce/2019/msg00001.html>)
+// Maximum slice count (255) for which we can find the page for interior pointers
+#define MI_MAX_SLICE_OFFSET_COUNT         ((MI_BLOCK_ALIGNMENT_MAX / MI_SEGMENT_SLICE_SIZE) - 1)
+
+// we never allocate more than PTRDIFF_MAX (see also <https://sourceware.org/ml/libc-announce/2019/msg00001.html>)
+// on 64-bit+ systems we also limit the maximum allocation size such that the slice count fits in 32-bits. (issue #877)
+#if (PTRDIFF_MAX > INT32_MAX) && (PTRDIFF_MAX >= (MI_SEGMENT_SLIZE_SIZE * UINT32_MAX))
+#define MI_MAX_ALLOC_SIZE   (MI_SEGMENT_SLICE_SIZE * (UINT32_MAX-1))
+#else
 #define MI_MAX_ALLOC_SIZE   PTRDIFF_MAX
+#endif
+
 
 // ------------------------------------------------------
 // Mimalloc pages contain allocated blocks
@@ -296,8 +308,8 @@ typedef uintptr_t mi_thread_free_t;
 // Notes:
 // - Access is optimized for `free.c:mi_free` and `alloc.c:mi_page_alloc`
 // - Using `uint16_t` does not seem to slow things down
-// - The size is 10 words on 64-bit which helps the page index calculations
-//   (and 12 words on 32-bit, and encoded free lists add 2 words)
+// - The size is 12 words on 64-bit which helps the page index calculations
+//   (and 14 words on 32-bit, and encoded free lists add 2 words)
 // - `xthread_free` uses the bottom bits as a delayed-free flags to optimize
 //   concurrent frees where only the first concurrent free adds to the owning
 //   heap `thread_delayed_free` list (see `free.c:mi_free_block_mt`).
@@ -307,12 +319,12 @@ typedef uintptr_t mi_thread_free_t;
 //   will be freed correctly even if only other threads free blocks.
 typedef struct mi_page_s {
   // "owned" by the segment
-  uint8_t               segment_idx;       // index in the segment `pages` array, `page == &segment->pages[page->segment_idx]`
-  uint8_t               segment_in_use:1;  // `true` if the segment allocated this page
+  uint32_t              slice_count;       // slices in this page (0 if not a page)
+  uint32_t              slice_offset;      // distance from the actual page data slice (0 if a page)
   uint8_t               is_committed:1;    // `true` if the page virtual memory is committed
   uint8_t               is_zero_init:1;    // `true` if the page was initially zero initialized
-  uint8_t               is_huge:1;         // `true` if the page is in a huge segment
-
+  uint8_t               is_huge:1;         // `true` if the page is in a huge segment (`segment->kind == MI_SEGMENT_HUGE`)
+                                           // padding
   // layout like this to optimize access in `mi_malloc` and `mi_free`
   uint16_t              capacity;          // number of blocks committed, must be the first field, see `segment.c:page_clear`
   uint16_t              reserved;          // number of blocks reserved in memory
@@ -336,12 +348,11 @@ typedef struct mi_page_s {
   _Atomic(mi_thread_free_t) xthread_free;  // list of deferred free blocks freed by other threads
   _Atomic(uintptr_t)        xheap;
 
-  struct mi_page_s*     next;              // next page owned by the heap with the same `block_size`
-  struct mi_page_s*     prev;              // previous page owned by the heap with the same `block_size`
+  struct mi_page_s*     next;              // next page owned by this thread with the same `block_size`
+  struct mi_page_s*     prev;              // previous page owned by this thread with the same `block_size`
 
-  #if MI_INTPTR_SIZE==4                    // pad to 12 words on 32-bit
+  // 64-bit 11 words, 32-bit 13 words, (+2 for secure)
   void* padding[1];
-  #endif
 } mi_page_t;
 
 
@@ -354,10 +365,44 @@ typedef enum mi_page_kind_e {
   MI_PAGE_SMALL,    // small blocks go into 64KiB pages inside a segment
   MI_PAGE_MEDIUM,   // medium blocks go into 512KiB pages inside a segment
   MI_PAGE_LARGE,    // larger blocks go into a single page spanning a whole segment
-  MI_PAGE_HUGE      // a huge page is a single page in a segment of variable size (but still 2MiB aligned)
-                    // used for blocks `> MI_LARGE_OBJ_SIZE_MAX` or an alignment `> MI_BLOCK_ALIGNMENT_MAX`.
+  MI_PAGE_HUGE      // a huge page is a single page in a segment of variable size
+                    // used for blocks `> MI_LARGE_OBJ_SIZE_MAX` or an aligment `> MI_BLOCK_ALIGNMENT_MAX`.
 } mi_page_kind_t;
 
+typedef enum mi_segment_kind_e {
+  MI_SEGMENT_NORMAL, // MI_SEGMENT_SIZE size with pages inside.
+  MI_SEGMENT_HUGE,   // segment with just one huge page inside.
+} mi_segment_kind_t;
+
+// ------------------------------------------------------
+// A segment holds a commit mask where a bit is set if
+// the corresponding MI_COMMIT_SIZE area is committed.
+// The MI_COMMIT_SIZE must be a multiple of the slice
+// size. If it is equal we have the most fine grained
+// decommit (but setting it higher can be more efficient).
+// The MI_MINIMAL_COMMIT_SIZE is the minimal amount that will
+// be committed in one go which can be set higher than
+// MI_COMMIT_SIZE for efficiency (while the decommit mask
+// is still tracked in fine-grained MI_COMMIT_SIZE chunks)
+// ------------------------------------------------------
+
+#define MI_MINIMAL_COMMIT_SIZE      (1*MI_SEGMENT_SLICE_SIZE)
+#define MI_COMMIT_SIZE              (MI_SEGMENT_SLICE_SIZE)              // 64KiB
+#define MI_COMMIT_MASK_BITS         (MI_SEGMENT_SIZE / MI_COMMIT_SIZE)
+#define MI_COMMIT_MASK_FIELD_BITS    MI_SIZE_BITS
+#define MI_COMMIT_MASK_FIELD_COUNT  (MI_COMMIT_MASK_BITS / MI_COMMIT_MASK_FIELD_BITS)
+
+#if (MI_COMMIT_MASK_BITS != (MI_COMMIT_MASK_FIELD_COUNT * MI_COMMIT_MASK_FIELD_BITS))
+#error "the segment size must be exactly divisible by the (commit size * size_t bits)"
+#endif
+
+typedef struct mi_commit_mask_s {
+  size_t mask[MI_COMMIT_MASK_FIELD_COUNT];
+} mi_commit_mask_t;
+
+typedef mi_page_t  mi_slice_t;
+typedef int64_t    mi_msecs_t;
+
 
 // ---------------------------------------------------------------
 // a memory id tracks the provenance of arena/OS allocated memory
@@ -401,43 +446,57 @@ typedef struct mi_memid_s {
 } mi_memid_t;
 
 
-// ---------------------------------------------------------------
-// Segments contain mimalloc pages
-// ---------------------------------------------------------------
+// -----------------------------------------------------------------------------------------
+// Segments are large allocated memory blocks (32mb on 64 bit) from arenas or the OS.
+//
+// Inside segments we allocated fixed size mimalloc pages (`mi_page_t`) that contain blocks.
+// The start of a segment is this structure with a fixed number of slice entries (`slices`)
+// usually followed by a guard OS page and the actual allocation area with pages.
+// While a page is not allocated, we view it's data as a `mi_slice_t` (instead of a `mi_page_t`).
+// Of any free area, the first slice has the info and `slice_offset == 0`; for any subsequent
+// slices part of the area, the `slice_offset` is the byte offset back to the first slice
+// (so we can quickly find the page info on a free, `internal.h:_mi_segment_page_of`).
+// For slices, the `block_size` field is repurposed to signify if a slice is used (`1`) or not (`0`).
+// Small and medium pages use a fixed amount of slices to reduce slice fragmentation, while
+// large and huge pages span a variable amount of slices.
+
 typedef struct mi_subproc_s mi_subproc_t;
 
-// Segments are large allocated memory blocks (2MiB on 64 bit) from the OS.
-// Inside segments we allocated fixed size _pages_ that contain blocks.
 typedef struct mi_segment_s {
   // constant fields
-  mi_memid_t           memid;            // memory id to track provenance
-  bool                 allow_decommit;
-  bool                 allow_purge;
-  size_t               segment_size;     // for huge pages this may be different from `MI_SEGMENT_SIZE`
-  mi_subproc_t*        subproc;          // segment belongs to sub process
+  mi_memid_t        memid;              // memory id for arena/OS allocation
+  bool              allow_decommit;     // can we decommmit the memory
+  bool              allow_purge;        // can we purge the memory (reset or decommit)
+  size_t            segment_size;
+  mi_subproc_t*     subproc;            // segment belongs to sub process
 
   // segment fields
-  struct mi_segment_s* next;             // must be the first (non-constant) segment field  -- see `segment.c:segment_init`
-  struct mi_segment_s* prev;
-  bool                 was_reclaimed;    // true if it was reclaimed (used to limit reclaim-on-free reclamation)
-  bool                 dont_free;        // can be temporarily true to ensure the segment is not freed
+  mi_msecs_t        purge_expire;       // purge slices in the `purge_mask` after this time
+  mi_commit_mask_t  purge_mask;         // slices that can be purged
+  mi_commit_mask_t  commit_mask;        // slices that are currently committed
 
-  size_t               abandoned;        // abandoned pages (i.e. the original owning thread stopped) (`abandoned <= used`)
-  size_t               abandoned_visits; // count how often this segment is visited for reclaiming (to force reclaim if it is too long)
+  // from here is zero initialized
+  struct mi_segment_s* next;            // the list of freed segments in the cache (must be first field, see `segment.c:mi_segment_init`)
+  bool              was_reclaimed;      // true if it was reclaimed (used to limit on-free reclamation)
+  bool              dont_free;          // can be temporarily true to ensure the segment is not freed
 
-  size_t               used;             // count of pages in use (`used <= capacity`)
-  size_t               capacity;         // count of available pages (`#free + used`)
-  size_t               segment_info_size;// space we are using from the first page for segment meta-data and possible guard pages.
-  uintptr_t            cookie;           // verify addresses in secure mode: `_mi_ptr_cookie(segment) == segment->cookie`
+  size_t            abandoned;          // abandoned pages (i.e. the original owning thread stopped) (`abandoned <= used`)
+  size_t            abandoned_visits;   // count how often this segment is visited during abondoned reclamation (to force reclaim if it takes too long)
+  size_t            used;               // count of pages in use
+  uintptr_t         cookie;             // verify addresses in debug mode: `mi_ptr_cookie(segment) == segment->cookie`
 
   struct mi_segment_s* abandoned_os_next; // only used for abandoned segments outside arena's, and only if `mi_option_visit_abandoned` is enabled
   struct mi_segment_s* abandoned_os_prev;
 
+  size_t            segment_slices;      // for huge segments this may be different from `MI_SLICES_PER_SEGMENT`
+  size_t            segment_info_slices; // initial count of slices that we are using for segment info and possible guard pages.
+
   // layout like this to optimize access in `mi_free`
+  mi_segment_kind_t kind;
+  size_t            slice_entries;       // entries in the `slices` array, at most `MI_SLICES_PER_SEGMENT`
   _Atomic(mi_threadid_t) thread_id;      // unique id of the thread owning this segment
-  size_t               page_shift;       // `1 << page_shift` == the page sizes == `page->block_size * page->reserved` (unless the first page, then `-segment_info_size`).
-  mi_page_kind_t       page_kind;        // kind of pages: small, medium, large, or huge
-  mi_page_t            pages[1];         // up to `MI_SMALL_PAGES_PER_SEGMENT` pages
+
+  mi_slice_t        slices[MI_SLICES_PER_SEGMENT+1];  // one extra final entry for huge blocks with large alignment
 } mi_segment_t;
 
 
@@ -541,20 +600,19 @@ struct mi_subproc_s {
 // Thread Local data
 // ------------------------------------------------------
 
-// Milliseconds as in `int64_t` to avoid overflows
-typedef int64_t  mi_msecs_t;
+// A "span" is is an available range of slices. The span queues keep
+// track of slice spans of at most the given `slice_count` (but more than the previous size class).
+typedef struct mi_span_queue_s {
+  mi_slice_t* first;
+  mi_slice_t* last;
+  size_t      slice_count;
+} mi_span_queue_t;
 
-// Queue of segments
-typedef struct mi_segment_queue_s {
-  mi_segment_t* first;
-  mi_segment_t* last;
-} mi_segment_queue_t;
+#define MI_SEGMENT_BIN_MAX (35)     // 35 == mi_segment_bin(MI_SLICES_PER_SEGMENT)
 
 // Segments thread local data
 typedef struct mi_segments_tld_s {
-  mi_segment_queue_t  small_free;   // queue of segments with free small pages
-  mi_segment_queue_t  medium_free;  // queue of segments with free medium pages
-  mi_page_queue_t     pages_purge;  // queue of freed pages that are delay purged
+  mi_span_queue_t     spans[MI_SEGMENT_BIN_MAX+1];  // free slice spans inside segments
   size_t              count;        // current number of segments;
   size_t              peak_count;   // peak number of segments
   size_t              current_size; // current size of all segments

readme.md

@@ -73,7 +73,7 @@ Enjoy!
 ### Branches
 
 * `master`: latest stable release (still based on `dev2`).
-* `dev`:  development branch for mimalloc v1. Use this branch for submitting PR's.
+* `dev`:  development branch for mimalloc v1. **Use this branch for submitting PR's**.
 * `dev2`: development branch for mimalloc v2. This branch is downstream of `dev` 
           (and is essentially equal to `dev` except for `src/segment.c`). Uses larger sliced segments to manage
           mimalloc pages that can reduce fragmentation.
@@ -84,7 +84,7 @@ Enjoy!
 
 ### Releases
 
-* 2025-03-28, `v1.9.3`, `v2.2.3`, `v3.0.3-beta`: Various small bug and build fixes, including:
+* 2025-03-28, `v1.9.3`, `v2.2.3`, `v3.0.3` (beta): Various small bug and build fixes, including:
   fix arm32 pre v7 builds, fix mingw build, get runtime statistics, improve statistic commit counts, 
   fix execution on non BMI1 x64 systems. 
 * 2025-03-06, `v1.9.2`, `v2.2.2`, `v3.0.2-beta`: Various small bug and build fixes. 

src/alloc-aligned.c

@@ -115,7 +115,7 @@ static mi_decl_noinline void* mi_heap_malloc_zero_aligned_at_overalloc(mi_heap_t
 
   // now zero the block if needed
   if (alignment > MI_BLOCK_ALIGNMENT_MAX) {
-    // for the tracker, on huge aligned allocations only from the start of the large block is defined
+    // for the tracker, on huge aligned allocations only the memory from the start of the large block is defined
     mi_track_mem_undefined(aligned_p, size);
     if (zero) {
       _mi_memzero_aligned(aligned_p, mi_usable_size(aligned_p));
@@ -217,6 +217,11 @@ mi_decl_nodiscard mi_decl_restrict void* mi_heap_malloc_aligned(mi_heap_t* heap,
   return mi_heap_malloc_aligned_at(heap, size, alignment, 0);
 }
 
+// ensure a definition is emitted
+#if defined(__cplusplus)
+void* _mi_extern_heap_malloc_aligned = (void*)&mi_heap_malloc_aligned;
+#endif
+
 // ------------------------------------------------------
 // Aligned Allocation
 // ------------------------------------------------------

src/alloc.c

@@ -83,7 +83,7 @@ extern inline void* _mi_page_malloc_zero(mi_heap_t* heap, mi_page_t* page, size_
 
   #if (MI_STAT>0)
   const size_t bsize = mi_page_usable_block_size(page);
-  if (bsize <= MI_LARGE_OBJ_SIZE_MAX) {
+  if (bsize <= MI_MEDIUM_OBJ_SIZE_MAX) {
     mi_heap_stat_increase(heap, malloc_normal, bsize);
     mi_heap_stat_counter_increase(heap, malloc_normal_count, 1);
     #if (MI_STAT>1)
@@ -630,7 +630,7 @@ static void* mi_block_ptr_set_guarded(mi_block_t* block, size_t obj_size) {
     // give up to place it right in front of the guard page if the offset is too large for unalignment
     offset = MI_BLOCK_ALIGNMENT_MAX;
   }
-  void* p = (uint8_t*)block + offset;  
+  void* p = (uint8_t*)block + offset;
   mi_track_align(block, p, offset, obj_size);
   mi_track_mem_defined(block, sizeof(mi_block_t));
   return p;
@@ -652,7 +652,7 @@ mi_decl_restrict void* _mi_heap_malloc_guarded(mi_heap_t* heap, size_t size, boo
   void* const p   = mi_block_ptr_set_guarded(block, obj_size);
 
   // stats
-  mi_track_malloc(p, size, zero);  
+  mi_track_malloc(p, size, zero);
   if (p != NULL) {
     if (!mi_heap_is_initialized(heap)) { heap = mi_prim_get_default_heap(); }
     #if MI_STAT>1
@@ -685,7 +685,7 @@ void* _mi_externs[] = {
   (void*)&mi_zalloc_small,
   (void*)&mi_heap_malloc,
   (void*)&mi_heap_zalloc,
-  (void*)&mi_heap_malloc_small
+  (void*)&mi_heap_malloc_small,
   // (void*)&mi_heap_alloc_new,
   // (void*)&mi_heap_alloc_new_n
 };

src/arena.c

@@ -99,6 +99,10 @@ bool _mi_arena_memid_is_suitable(mi_memid_t memid, mi_arena_id_t request_arena_i
   }
 }
 
+bool _mi_arena_memid_is_os_allocated(mi_memid_t memid) {
+  return (memid.memkind == MI_MEM_OS);
+}
+
 size_t mi_arena_get_count(void) {
   return mi_atomic_load_relaxed(&mi_arena_count);
 }

src/bitmap.c

@@ -34,17 +34,17 @@ static inline size_t mi_bitmap_mask_(size_t count, size_t bitidx) {
 }
 
 
-
 /* -----------------------------------------------------------
   Claim a bit sequence atomically
 ----------------------------------------------------------- */
 
 // Try to atomically claim a sequence of `count` bits in a single
 // field at `idx` in `bitmap`. Returns `true` on success.
-bool _mi_bitmap_try_find_claim_field(mi_bitmap_t bitmap, size_t idx, const size_t count, mi_bitmap_index_t* bitmap_idx)
+inline bool _mi_bitmap_try_find_claim_field(mi_bitmap_t bitmap, size_t idx, const size_t count, mi_bitmap_index_t* bitmap_idx)
 {
   mi_assert_internal(bitmap_idx != NULL);
   mi_assert_internal(count <= MI_BITMAP_FIELD_BITS);
+  mi_assert_internal(count > 0);
   mi_bitmap_field_t* field = &bitmap[idx];
   size_t map  = mi_atomic_load_relaxed(field);
   if (map==MI_BITMAP_FIELD_FULL) return false; // short cut
@@ -94,9 +94,9 @@ bool _mi_bitmap_try_find_claim_field(mi_bitmap_t bitmap, size_t idx, const size_
   return false;
 }
 
-
+// Find `count` bits of 0 and set them to 1 atomically; returns `true` on success.
 // Starts at idx, and wraps around to search in all `bitmap_fields` fields.
-// For now, `count` can be at most MI_BITMAP_FIELD_BITS and will never cross fields.
+// `count` can be at most MI_BITMAP_FIELD_BITS and will never cross fields.
 bool _mi_bitmap_try_find_from_claim(mi_bitmap_t bitmap, const size_t bitmap_fields, const size_t start_field_idx, const size_t count, mi_bitmap_index_t* bitmap_idx) {
   size_t idx = start_field_idx;
   for (size_t visited = 0; visited < bitmap_fields; visited++, idx++) {
@@ -108,6 +108,24 @@ bool _mi_bitmap_try_find_from_claim(mi_bitmap_t bitmap, const size_t bitmap_fiel
   return false;
 }
 
+// Like _mi_bitmap_try_find_from_claim but with an extra predicate that must be fullfilled
+bool _mi_bitmap_try_find_from_claim_pred(mi_bitmap_t bitmap, const size_t bitmap_fields, 
+            const size_t start_field_idx, const size_t count, 
+            mi_bitmap_pred_fun_t pred_fun, void* pred_arg,            
+            mi_bitmap_index_t* bitmap_idx) {
+  size_t idx = start_field_idx;
+  for (size_t visited = 0; visited < bitmap_fields; visited++, idx++) {
+    if (idx >= bitmap_fields) idx = 0; // wrap
+    if (_mi_bitmap_try_find_claim_field(bitmap, idx, count, bitmap_idx)) {
+      if (pred_fun == NULL || pred_fun(*bitmap_idx, pred_arg)) { 
+        return true;
+      }
+      // predicate returned false, unclaim and look further
+      _mi_bitmap_unclaim(bitmap, bitmap_fields, count, *bitmap_idx);
+    }
+  }
+  return false;
+}
 
 // Set `count` bits at `bitmap_idx` to 0 atomically
 // Returns `true` if all `count` bits were 1 previously.
@@ -228,7 +246,7 @@ static bool mi_bitmap_try_find_claim_field_across(mi_bitmap_t bitmap, size_t bit
 
   // intermediate fields
   while (++field < final_field) {
-    newmap = mi_bitmap_mask_(MI_BITMAP_FIELD_BITS, 0);
+    newmap = MI_BITMAP_FIELD_FULL;
     map = 0;
     if (!mi_atomic_cas_strong_acq_rel(field, &map, newmap)) { goto rollback; }
   }
@@ -250,7 +268,7 @@ rollback:
   // (we just failed to claim `field` so decrement first)
   while (--field > initial_field) {
     newmap = 0;
-    map = mi_bitmap_mask_(MI_BITMAP_FIELD_BITS, 0);
+    map = MI_BITMAP_FIELD_FULL;
     mi_assert_internal(mi_atomic_load_relaxed(field) == map);
     mi_atomic_store_release(field, newmap);
   }

src/bitmap.h

@@ -44,6 +44,11 @@ static inline mi_bitmap_index_t mi_bitmap_index_create(size_t idx, size_t bitidx
   return mi_bitmap_index_create_ex(idx,bitidx);
 }
 
+// Create a bit index.
+static inline mi_bitmap_index_t mi_bitmap_index_create_from_bit(size_t full_bitidx) {  
+  return mi_bitmap_index_create(full_bitidx / MI_BITMAP_FIELD_BITS, full_bitidx % MI_BITMAP_FIELD_BITS);
+}
+
 // Get the field index from a bit index.
 static inline size_t mi_bitmap_index_field(mi_bitmap_index_t bitmap_idx) {
   return (bitmap_idx / MI_BITMAP_FIELD_BITS);
@@ -71,6 +76,10 @@ bool _mi_bitmap_try_find_claim_field(mi_bitmap_t bitmap, size_t idx, const size_
 // For now, `count` can be at most MI_BITMAP_FIELD_BITS and will never cross fields.
 bool _mi_bitmap_try_find_from_claim(mi_bitmap_t bitmap, const size_t bitmap_fields, const size_t start_field_idx, const size_t count, mi_bitmap_index_t* bitmap_idx);
 
+// Like _mi_bitmap_try_find_from_claim but with an extra predicate that must be fullfilled
+typedef bool (mi_cdecl *mi_bitmap_pred_fun_t)(mi_bitmap_index_t bitmap_idx, void* pred_arg);
+bool _mi_bitmap_try_find_from_claim_pred(mi_bitmap_t bitmap, const size_t bitmap_fields, const size_t start_field_idx, const size_t count, mi_bitmap_pred_fun_t pred_fun, void* pred_arg, mi_bitmap_index_t* bitmap_idx);
+
 // Set `count` bits at `bitmap_idx` to 0 atomically
 // Returns `true` if all `count` bits were 1 previously.
 bool _mi_bitmap_unclaim(mi_bitmap_t bitmap, size_t bitmap_fields, size_t count, mi_bitmap_index_t bitmap_idx);

src/free.c

@@ -35,7 +35,9 @@ static inline void mi_free_block_local(mi_page_t* page, mi_block_t* block, bool
   mi_check_padding(page, block);
   if (track_stats) { mi_stat_free(page, block); }
   #if (MI_DEBUG>0) && !MI_TRACK_ENABLED  && !MI_TSAN && !MI_GUARDED
-  memset(block, MI_DEBUG_FREED, mi_page_block_size(page));
+  if (!mi_page_is_huge(page)) {   // huge page content may be already decommitted
+    memset(block, MI_DEBUG_FREED, mi_page_block_size(page));
+  }
   #endif
   if (track_stats) { mi_track_free_size(block, mi_page_usable_size_of(page, block)); } // faster then mi_usable_size as we already know the page and that p is unaligned
 
@@ -121,10 +123,16 @@ static inline mi_segment_t* mi_checked_ptr_segment(const void* p, const char* ms
 
   #if (MI_DEBUG>0)
   if mi_unlikely(!mi_is_in_heap_region(p)) {
-    _mi_warning_message("%s: pointer might not point to a valid heap region: %p\n"
-      "(this may still be a valid very large allocation (over 64MiB))\n", msg, p);
-    if mi_likely(_mi_ptr_cookie(segment) == segment->cookie) {
-      _mi_warning_message("(yes, the previous pointer %p was valid after all)\n", p);
+  #if (MI_INTPTR_SIZE == 8 && defined(__linux__))
+    if (((uintptr_t)p >> 40) != 0x7F) { // linux tends to align large blocks above 0x7F000000000 (issue #640)
+  #else
+    {
+  #endif
+      _mi_warning_message("%s: pointer might not point to a valid heap region: %p\n"
+        "(this may still be a valid very large allocation (over 64MiB))\n", msg, p);
+      if mi_likely(_mi_ptr_cookie(segment) == segment->cookie) {
+        _mi_warning_message("(yes, the previous pointer %p was valid after all)\n", p);
+      }
     }
   }
   #endif
@@ -272,7 +280,7 @@ static void mi_decl_noinline mi_free_block_mt(mi_page_t* page, mi_segment_t* seg
   // for small size, ensure we can fit the delayed thread pointers without triggering overflow detection
   _mi_padding_shrink(page, block, sizeof(mi_block_t));
 
-  if (segment->page_kind == MI_PAGE_HUGE) {
+  if (segment->kind == MI_SEGMENT_HUGE) {
     #if MI_HUGE_PAGE_ABANDON
     // huge page segments are always abandoned and can be freed immediately
     _mi_segment_huge_page_free(segment, page, block);
@@ -521,15 +529,17 @@ static void mi_stat_free(const mi_page_t* page, const mi_block_t* block) {
   // const size_t usize = mi_page_usable_size_of(page, block);
   // mi_heap_stat_decrease(heap, malloc_requested, usize);
   // #endif
-  if (bsize <= MI_LARGE_OBJ_SIZE_MAX) {
+  if (bsize <= MI_MEDIUM_OBJ_SIZE_MAX) {
     mi_heap_stat_decrease(heap, malloc_normal, bsize);
     #if (MI_STAT > 1)
     mi_heap_stat_decrease(heap, malloc_bins[_mi_bin(bsize)], 1);
     #endif
   }
+  //else if (bsize <= MI_LARGE_OBJ_SIZE_MAX) {
+  //  mi_heap_stat_decrease(heap, malloc_large, bsize);
+  //}
   else {
-    const size_t bpsize = mi_page_block_size(page);  // match stat in page.c:mi_huge_page_alloc
-    mi_heap_stat_decrease(heap, malloc_huge, bpsize);
+    mi_heap_stat_decrease(heap, malloc_huge, bsize);
   }
 }
 #else

src/heap.c

@@ -95,6 +95,11 @@ static bool mi_heap_page_collect(mi_heap_t* heap, mi_page_queue_t* pq, mi_page_t
   mi_assert_internal(mi_heap_page_is_valid(heap, pq, page, NULL, NULL));
   mi_collect_t collect = *((mi_collect_t*)arg_collect);
   _mi_page_free_collect(page, collect >= MI_FORCE);
+  if (collect == MI_FORCE) {
+    // note: call before a potential `_mi_page_free` as the segment may be freed if this was the last used page in that segment.
+    mi_segment_t* segment = _mi_page_segment(page);
+    _mi_segment_collect(segment, true /* force? */);
+  }
   if (mi_page_all_free(page)) {
     // no more used blocks, free the page.
     // note: this will free retired pages as well.
@@ -127,14 +132,15 @@ static void mi_heap_collect_ex(mi_heap_t* heap, mi_collect_t collect)
   const bool is_main_thread = (_mi_is_main_thread() && heap->thread_id == _mi_thread_id());
 
   // note: never reclaim on collect but leave it to threads that need storage to reclaim
-  if (
-  #ifdef NDEBUG
+  const bool force_main =
+    #ifdef NDEBUG
       collect == MI_FORCE
-  #else
+    #else
       collect >= MI_FORCE
-  #endif
-    && is_main_thread && mi_heap_is_backing(heap) && !heap->no_reclaim)
-  {
+    #endif
+      && is_main_thread && mi_heap_is_backing(heap) && !heap->no_reclaim;
+
+  if (force_main) {
     // the main thread is abandoned (end-of-program), try to reclaim all abandoned segments.
     // if all memory is freed by now, all segments should be freed.
     // note: this only collects in the current subprocess
@@ -157,8 +163,9 @@ static void mi_heap_collect_ex(mi_heap_t* heap, mi_collect_t collect)
   mi_heap_visit_pages(heap, &mi_heap_page_collect, &collect, NULL);
   mi_assert_internal( collect != MI_ABANDON || mi_atomic_load_ptr_acquire(mi_block_t,&heap->thread_delayed_free) == NULL );
 
-  // collect segments (purge pages, this can be expensive so don't force on abandonment)
-  _mi_segments_collect(collect == MI_FORCE, &heap->tld->segments);
+  // collect abandoned segments (in particular, purge expired parts of segments in the abandoned segment list)
+  // note: forced purge can be quite expensive if many threads are created/destroyed so we do not force on abandonment
+  _mi_abandoned_collect(heap, collect == MI_FORCE /* force? */, &heap->tld->segments);
 
   // if forced, collect thread data cache on program-exit (or shared library unload)
   if (force && is_main_thread && mi_heap_is_backing(heap)) {
@@ -328,8 +335,14 @@ static bool _mi_heap_page_destroy(mi_heap_t* heap, mi_page_queue_t* pq, mi_page_
 
   // stats
   const size_t bsize = mi_page_block_size(page);
-  if (bsize > MI_LARGE_OBJ_SIZE_MAX) {
-    mi_heap_stat_decrease(heap, malloc_huge, bsize);
+  if (bsize > MI_MEDIUM_OBJ_SIZE_MAX) {
+    //if (bsize <= MI_LARGE_OBJ_SIZE_MAX) {
+    //  mi_heap_stat_decrease(heap, malloc_large, bsize);
+    //}
+    //else 
+    {
+      mi_heap_stat_decrease(heap, malloc_huge, bsize);
+    }
   }
   #if (MI_STAT>0)
   _mi_page_free_collect(page, false);  // update used count

src/init.c

@@ -34,13 +34,12 @@ const mi_page_t _mi_page_empty = {
   MI_ATOMIC_VAR_INIT(0), // xthread_free
   MI_ATOMIC_VAR_INIT(0), // xheap
   NULL, NULL
-  #if MI_INTPTR_SIZE==4
-  , { NULL }
-  #endif
+  , { 0 }  // padding
 };
 
 #define MI_PAGE_EMPTY() ((mi_page_t*)&_mi_page_empty)
 
+#if (MI_SMALL_WSIZE_MAX==128)
 #if (MI_PADDING>0) && (MI_INTPTR_SIZE >= 8)
 #define MI_SMALL_PAGES_EMPTY  { MI_INIT128(MI_PAGE_EMPTY), MI_PAGE_EMPTY(), MI_PAGE_EMPTY() }
 #elif (MI_PADDING>0)
@@ -48,7 +47,9 @@ const mi_page_t _mi_page_empty = {
 #else
 #define MI_SMALL_PAGES_EMPTY  { MI_INIT128(MI_PAGE_EMPTY), MI_PAGE_EMPTY() }
 #endif
-
+#else
+#error "define right initialization sizes corresponding to MI_SMALL_WSIZE_MAX"
+#endif
 
 // Empty page queues for every bin
 #define QNULL(sz)  { NULL, NULL, (sz)*sizeof(uintptr_t) }
@@ -63,8 +64,8 @@ const mi_page_t _mi_page_empty = {
     QNULL( 10240), QNULL( 12288), QNULL( 14336), QNULL( 16384), QNULL( 20480), QNULL( 24576), QNULL( 28672), QNULL( 32768), /* 56 */ \
     QNULL( 40960), QNULL( 49152), QNULL( 57344), QNULL( 65536), QNULL( 81920), QNULL( 98304), QNULL(114688), QNULL(131072), /* 64 */ \
     QNULL(163840), QNULL(196608), QNULL(229376), QNULL(262144), QNULL(327680), QNULL(393216), QNULL(458752), QNULL(524288), /* 72 */ \
-    QNULL(MI_LARGE_OBJ_WSIZE_MAX + 1  /* 655360, Huge queue */), \
-    QNULL(MI_LARGE_OBJ_WSIZE_MAX + 2) /* Full queue */ }
+    QNULL(MI_MEDIUM_OBJ_WSIZE_MAX + 1  /* 655360, Huge queue */), \
+    QNULL(MI_MEDIUM_OBJ_WSIZE_MAX + 2) /* Full queue */ }
 
 #define MI_STAT_COUNT_NULL()  {0,0,0}
 
@@ -86,6 +87,18 @@ const mi_page_t _mi_page_empty = {
   { MI_INIT74(MI_STAT_COUNT_NULL) }, \
   { MI_INIT74(MI_STAT_COUNT_NULL) }
 
+
+// Empty slice span queues for every bin
+#define SQNULL(sz)  { NULL, NULL, sz }
+#define MI_SEGMENT_SPAN_QUEUES_EMPTY \
+  { SQNULL(1), \
+    SQNULL(     1), SQNULL(     2), SQNULL(     3), SQNULL(     4), SQNULL(     5), SQNULL(     6), SQNULL(     7), SQNULL(    10), /*  8 */ \
+    SQNULL(    12), SQNULL(    14), SQNULL(    16), SQNULL(    20), SQNULL(    24), SQNULL(    28), SQNULL(    32), SQNULL(    40), /* 16 */ \
+    SQNULL(    48), SQNULL(    56), SQNULL(    64), SQNULL(    80), SQNULL(    96), SQNULL(   112), SQNULL(   128), SQNULL(   160), /* 24 */ \
+    SQNULL(   192), SQNULL(   224), SQNULL(   256), SQNULL(   320), SQNULL(   384), SQNULL(   448), SQNULL(   512), SQNULL(   640), /* 32 */ \
+    SQNULL(   768), SQNULL(   896), SQNULL(  1024) /* 35 */ }
+
+
 // --------------------------------------------------------
 // Statically allocate an empty heap as the initial
 // thread local value for the default heap,
@@ -116,6 +129,17 @@ mi_decl_cache_align const mi_heap_t _mi_heap_empty = {
   MI_PAGE_QUEUES_EMPTY
 };
 
+static mi_decl_cache_align mi_subproc_t mi_subproc_default;
+
+#define tld_empty_stats  ((mi_stats_t*)((uint8_t*)&tld_empty + offsetof(mi_tld_t,stats)))
+
+mi_decl_cache_align static const mi_tld_t tld_empty = {
+  0,
+  false,
+  NULL, NULL,
+  { MI_SEGMENT_SPAN_QUEUES_EMPTY, 0, 0, 0, 0, 0, &mi_subproc_default, tld_empty_stats }, // segments
+  { MI_STAT_VERSION, MI_STATS_NULL }       // stats
+};
 
 mi_threadid_t _mi_thread_id(void) mi_attr_noexcept {
   return _mi_prim_thread_id();
@@ -126,15 +150,10 @@ mi_decl_thread mi_heap_t* _mi_heap_default = (mi_heap_t*)&_mi_heap_empty;
 
 extern mi_decl_hidden mi_heap_t _mi_heap_main;
 
-static mi_decl_cache_align mi_subproc_t mi_subproc_default;
-
 static mi_decl_cache_align mi_tld_t tld_main = {
   0, false,
-  &_mi_heap_main, &_mi_heap_main,
-  { { NULL, NULL }, {NULL ,NULL}, {NULL ,NULL, 0},
-    0, 0, 0, 0, 0, &mi_subproc_default,
-    &tld_main.stats
-  }, // segments
+  &_mi_heap_main, & _mi_heap_main,
+  { MI_SEGMENT_SPAN_QUEUES_EMPTY, 0, 0, 0, 0, 0, &mi_subproc_default, &tld_main.stats }, // segments
   { MI_STAT_VERSION, MI_STATS_NULL }       // stats
 };
 
@@ -391,7 +410,7 @@ static bool _mi_thread_heap_init(void) {
 
 // initialize thread local data
 void _mi_tld_init(mi_tld_t* tld, mi_heap_t* bheap) {
-  _mi_memzero_aligned(tld,sizeof(mi_tld_t));
+  _mi_memcpy_aligned(tld, &tld_empty, sizeof(mi_tld_t));
   tld->heap_backing = bheap;
   tld->heaps = NULL;
   tld->segments.subproc = &mi_subproc_default;
@@ -432,7 +451,10 @@ static bool _mi_thread_heap_done(mi_heap_t* heap) {
 
   // free if not the main thread
   if (heap != &_mi_heap_main) {
-    mi_assert_internal(heap->tld->segments.count == 0 || heap->thread_id != _mi_thread_id());
+    // the following assertion does not always hold for huge segments as those are always treated
+    // as abondened: one may allocate it in one thread, but deallocate in another in which case
+    // the count can be too large or negative. todo: perhaps not count huge segments? see issue #363
+    // mi_assert_internal(heap->tld->segments.count == 0 || heap->thread_id != _mi_thread_id());
     mi_thread_data_free((mi_thread_data_t*)heap);
   }
   else {
@@ -647,7 +669,7 @@ void mi_process_init(void) mi_attr_noexcept {
   if (mi_option_is_enabled(mi_option_reserve_os_memory)) {
     long ksize = mi_option_get(mi_option_reserve_os_memory);
     if (ksize > 0) {
-      mi_reserve_os_memory((size_t)ksize*MI_KiB, true, true);
+      mi_reserve_os_memory((size_t)ksize*MI_KiB, true /* commit? */, true /* allow large pages? */);
     }
   }
 }

src/options.c

@@ -106,11 +106,11 @@ typedef struct mi_option_desc_s {
 static mi_option_desc_t options[_mi_option_last] =
 {
   // stable options
-#if MI_DEBUG || defined(MI_SHOW_ERRORS)
+  #if MI_DEBUG || defined(MI_SHOW_ERRORS)
   { 1, UNINIT, MI_OPTION(show_errors) },
-#else
+  #else
   { 0, UNINIT, MI_OPTION(show_errors) },
-#endif
+  #endif
   { 0, UNINIT, MI_OPTION(show_stats) },
   { MI_DEFAULT_VERBOSE, UNINIT, MI_OPTION(verbose) },
 
@@ -129,7 +129,7 @@ static mi_option_desc_t options[_mi_option_last] =
        UNINIT, MI_OPTION(reserve_os_memory)     },      // reserve N KiB OS memory in advance (use `option_get_size`)
   { 0, UNINIT, MI_OPTION(deprecated_segment_cache) },   // cache N segments per thread
   { 0, UNINIT, MI_OPTION(deprecated_page_reset) },      // reset page memory on free
-  { 0, UNINIT, MI_OPTION(abandoned_page_purge) },       // purge free page memory when a thread terminates
+  { 0, UNINIT, MI_OPTION_LEGACY(abandoned_page_purge,abandoned_page_reset) },       // reset free page memory when a thread terminates
   { 0, UNINIT, MI_OPTION(deprecated_segment_reset) },   // reset segment memory on free (needs eager commit)
 #if defined(__NetBSD__)
   { 0, UNINIT, MI_OPTION(eager_commit_delay) },         // the first N segments per thread are not eagerly committed

src/os.c

@@ -91,21 +91,6 @@ void _mi_os_init(void) {
 bool _mi_os_decommit(void* addr, size_t size);
 bool _mi_os_commit(void* addr, size_t size, bool* is_zero);
 
-static inline uintptr_t _mi_align_down(uintptr_t sz, size_t alignment) {
-  mi_assert_internal(alignment != 0);
-  uintptr_t mask = alignment - 1;
-  if ((alignment & mask) == 0) { // power of two?
-    return (sz & ~mask);
-  }
-  else {
-    return ((sz / alignment) * alignment);
-  }
-}
-
-static void* mi_align_down_ptr(void* p, size_t alignment) {
-  return (void*)_mi_align_down((uintptr_t)p, alignment);
-}
-
 
 /* -----------------------------------------------------------
   aligned hinting
@@ -519,7 +504,7 @@ bool _mi_os_purge_ex(void* p, size_t size, bool allow_reset, size_t stat_size)
   mi_os_stat_increase(purged, size);
 
   if (mi_option_is_enabled(mi_option_purge_decommits) &&   // should decommit?
-    !_mi_preloading())                                     // don't decommit during preloading (unsafe)
+      !_mi_preloading())                                   // don't decommit during preloading (unsafe)
   {
     bool needs_recommit = true;
     mi_os_decommit_ex(p, size, &needs_recommit, stat_size);
@@ -539,7 +524,6 @@ bool _mi_os_purge(void* p, size_t size) {
   return _mi_os_purge_ex(p, size, true, size);
 }
 
-
 // Protect a region in memory to be not accessible.
 static  bool mi_os_protectx(void* addr, size_t size, bool protect) {
   // page align conservatively within the range

src/page-queue.c

@@ -12,7 +12,7 @@ terms of the MIT license. A copy of the license can be found in the file
 #ifndef MI_IN_PAGE_C
 #error "this file should be included from 'page.c'"
 // include to help an IDE
-#include "mimalloc.h"     
+#include "mimalloc.h"
 #include "mimalloc/internal.h"
 #include "mimalloc/atomic.h"
 #endif
@@ -38,15 +38,15 @@ terms of the MIT license. A copy of the license can be found in the file
 
 
 static inline bool mi_page_queue_is_huge(const mi_page_queue_t* pq) {
-  return (pq->block_size == (MI_LARGE_OBJ_SIZE_MAX+sizeof(uintptr_t)));
+  return (pq->block_size == (MI_MEDIUM_OBJ_SIZE_MAX+sizeof(uintptr_t)));
 }
 
 static inline bool mi_page_queue_is_full(const mi_page_queue_t* pq) {
-  return (pq->block_size == (MI_LARGE_OBJ_SIZE_MAX+(2*sizeof(uintptr_t))));
+  return (pq->block_size == (MI_MEDIUM_OBJ_SIZE_MAX+(2*sizeof(uintptr_t))));
 }
 
 static inline bool mi_page_queue_is_special(const mi_page_queue_t* pq) {
-  return (pq->block_size > MI_LARGE_OBJ_SIZE_MAX);
+  return (pq->block_size > MI_MEDIUM_OBJ_SIZE_MAX);
 }
 
 /* -----------------------------------------------------------
@@ -58,7 +58,7 @@ static inline bool mi_page_queue_is_special(const mi_page_queue_t* pq) {
 // We use `wsize` for the size in "machine word sizes",
 // i.e. byte size == `wsize*sizeof(void*)`.
 static inline size_t mi_bin(size_t size) {
-  size_t wsize = _mi_wsize_from_size(size);  
+  size_t wsize = _mi_wsize_from_size(size);
 #if defined(MI_ALIGN4W)
   if mi_likely(wsize <= 4) {
     return (wsize <= 1 ? 1 : (wsize+1)&~1); // round to double word sizes
@@ -72,7 +72,7 @@ static inline size_t mi_bin(size_t size) {
     return (wsize == 0 ? 1 : wsize);
   }
 #endif
-  else if mi_unlikely(wsize > MI_LARGE_OBJ_WSIZE_MAX) {
+  else if mi_unlikely(wsize > MI_MEDIUM_OBJ_WSIZE_MAX) {
     return MI_BIN_HUGE;
   }
   else {
@@ -107,7 +107,7 @@ size_t _mi_bin_size(size_t bin) {
 
 // Good size for allocation
 size_t mi_good_size(size_t size) mi_attr_noexcept {
-  if (size <= MI_LARGE_OBJ_SIZE_MAX) {
+  if (size <= MI_MEDIUM_OBJ_SIZE_MAX) {
     return _mi_bin_size(mi_bin(size + MI_PADDING_SIZE));
   }
   else {
@@ -136,6 +136,10 @@ static bool mi_heap_contains_queue(const mi_heap_t* heap, const mi_page_queue_t*
 }
 #endif
 
+static inline bool mi_page_is_large_or_huge(const mi_page_t* page) {
+  return (mi_page_block_size(page) > MI_MEDIUM_OBJ_SIZE_MAX || mi_page_is_huge(page));
+}
+
 static size_t mi_page_bin(const mi_page_t* page) {
   const size_t bin = (mi_page_is_in_full(page) ? MI_BIN_FULL : (mi_page_is_huge(page) ? MI_BIN_HUGE : mi_bin(mi_page_block_size(page))));
   mi_assert_internal(bin <= MI_BIN_FULL);
@@ -147,7 +151,7 @@ static mi_page_queue_t* mi_heap_page_queue_of(mi_heap_t* heap, const mi_page_t*
   const size_t bin = mi_page_bin(page);
   mi_page_queue_t* pq = &heap->pages[bin];
   mi_assert_internal((mi_page_block_size(page) == pq->block_size) ||
-                       (mi_page_is_huge(page) && mi_page_queue_is_huge(pq)) ||
+                       (mi_page_is_large_or_huge(page) && mi_page_queue_is_huge(pq)) ||
                          (mi_page_is_in_full(page) && mi_page_queue_is_full(pq)));
   return pq;
 }
@@ -210,10 +214,11 @@ static bool mi_page_queue_is_empty(mi_page_queue_t* queue) {
 static void mi_page_queue_remove(mi_page_queue_t* queue, mi_page_t* page) {
   mi_assert_internal(page != NULL);
   mi_assert_expensive(mi_page_queue_contains(queue, page));
-  mi_assert_internal(mi_page_block_size(page) == queue->block_size || 
-                      (mi_page_is_huge(page) && mi_page_queue_is_huge(queue)) || 
+  mi_assert_internal(mi_page_block_size(page) == queue->block_size ||
+                      (mi_page_is_large_or_huge(page) && mi_page_queue_is_huge(queue)) ||
                         (mi_page_is_in_full(page) && mi_page_queue_is_full(queue)));
   mi_heap_t* heap = mi_page_heap(page);
+
   if (page->prev != NULL) page->prev->next = page->next;
   if (page->next != NULL) page->next->prev = page->prev;
   if (page == queue->last)  queue->last = page->prev;
@@ -235,10 +240,10 @@ static void mi_page_queue_push(mi_heap_t* heap, mi_page_queue_t* queue, mi_page_
   mi_assert_internal(mi_page_heap(page) == heap);
   mi_assert_internal(!mi_page_queue_contains(queue, page));
   #if MI_HUGE_PAGE_ABANDON
-  mi_assert_internal(_mi_page_segment(page)->page_kind != MI_PAGE_HUGE);
+  mi_assert_internal(_mi_page_segment(page)->kind != MI_SEGMENT_HUGE);
   #endif
   mi_assert_internal(mi_page_block_size(page) == queue->block_size ||
-                      (mi_page_is_huge(page) && mi_page_queue_is_huge(queue)) ||
+                      (mi_page_is_large_or_huge(page) && mi_page_queue_is_huge(queue)) ||
                         (mi_page_is_in_full(page) && mi_page_queue_is_full(queue)));
 
   mi_page_set_in_full(page, mi_page_queue_is_full(queue));
@@ -277,8 +282,8 @@ static void mi_page_queue_enqueue_from_ex(mi_page_queue_t* to, mi_page_queue_t*
   mi_assert_internal((bsize == to->block_size && bsize == from->block_size) ||
                      (bsize == to->block_size && mi_page_queue_is_full(from)) ||
                      (bsize == from->block_size && mi_page_queue_is_full(to)) ||
-                     (mi_page_is_huge(page) && mi_page_queue_is_huge(to)) ||
-                     (mi_page_is_huge(page) && mi_page_queue_is_full(to)));
+                     (mi_page_is_large_or_huge(page) && mi_page_queue_is_huge(to)) ||
+                     (mi_page_is_large_or_huge(page) && mi_page_queue_is_full(to)));
 
   mi_heap_t* heap = mi_page_heap(page);
 
@@ -317,8 +322,8 @@ static void mi_page_queue_enqueue_from_ex(mi_page_queue_t* to, mi_page_queue_t*
       page->prev = to->first;
       page->next = next;
       to->first->next = page;
-      if (next != NULL) { 
-        next->prev = page; 
+      if (next != NULL) {
+        next->prev = page;
       }
       else {
         to->last = page;

src/page.c

@@ -82,11 +82,9 @@ static bool mi_page_is_valid_init(mi_page_t* page) {
   mi_assert_internal(page->used <= page->capacity);
   mi_assert_internal(page->capacity <= page->reserved);
 
-  // const size_t bsize = mi_page_block_size(page);
-  mi_segment_t* segment = _mi_page_segment(page);
   uint8_t* start = mi_page_start(page);
-  mi_assert_internal(start == _mi_segment_page_start(segment,page,NULL));
-  mi_assert_internal(page->is_huge == (segment->page_kind == MI_PAGE_HUGE));
+  mi_assert_internal(start == _mi_segment_page_start(_mi_page_segment(page), page, NULL));
+  mi_assert_internal(page->is_huge == (_mi_page_segment(page)->kind == MI_SEGMENT_HUGE));
   //mi_assert_internal(start + page->capacity*page->block_size == page->top);
 
   mi_assert_internal(mi_page_list_is_valid(page,page->free));
@@ -123,14 +121,15 @@ bool _mi_page_is_valid(mi_page_t* page) {
   #endif
   if (mi_page_heap(page)!=NULL) {
     mi_segment_t* segment = _mi_page_segment(page);
-    mi_assert_internal(!_mi_process_is_initialized || segment->thread_id == mi_page_heap(page)->thread_id || segment->thread_id==0);
+
+    mi_assert_internal(!_mi_process_is_initialized || segment->thread_id==0 || segment->thread_id == mi_page_heap(page)->thread_id);
     #if MI_HUGE_PAGE_ABANDON
-    if (segment->page_kind != MI_PAGE_HUGE)
+    if (segment->kind != MI_SEGMENT_HUGE)
     #endif
     {
       mi_page_queue_t* pq = mi_page_queue_of(page);
       mi_assert_internal(mi_page_queue_contains(pq, page));
-      mi_assert_internal(pq->block_size==mi_page_block_size(page) || mi_page_block_size(page) > MI_LARGE_OBJ_SIZE_MAX || mi_page_is_in_full(page));
+      mi_assert_internal(pq->block_size==mi_page_block_size(page) || mi_page_block_size(page) > MI_MEDIUM_OBJ_SIZE_MAX || mi_page_is_in_full(page));
       mi_assert_internal(mi_heap_contains_queue(mi_page_heap(page),pq));
     }
   }
@@ -257,10 +256,11 @@ void _mi_page_free_collect(mi_page_t* page, bool force) {
 // called from segments when reclaiming abandoned pages
 void _mi_page_reclaim(mi_heap_t* heap, mi_page_t* page) {
   mi_assert_expensive(mi_page_is_valid_init(page));
+
   mi_assert_internal(mi_page_heap(page) == heap);
   mi_assert_internal(mi_page_thread_free_flag(page) != MI_NEVER_DELAYED_FREE);
   #if MI_HUGE_PAGE_ABANDON
-  mi_assert_internal(_mi_page_segment(page)->page_kind != MI_PAGE_HUGE);
+  mi_assert_internal(_mi_page_segment(page)->kind != MI_SEGMENT_HUGE);
   #endif
 
   // TODO: push on full queue immediately if it is full?
@@ -274,7 +274,7 @@ static mi_page_t* mi_page_fresh_alloc(mi_heap_t* heap, mi_page_queue_t* pq, size
   #if !MI_HUGE_PAGE_ABANDON
   mi_assert_internal(pq != NULL);
   mi_assert_internal(mi_heap_contains_queue(heap, pq));
-  mi_assert_internal(page_alignment > 0 || block_size > MI_LARGE_OBJ_SIZE_MAX || block_size == pq->block_size);
+  mi_assert_internal(page_alignment > 0 || block_size > MI_MEDIUM_OBJ_SIZE_MAX || block_size == pq->block_size);
   #endif
   mi_page_t* page = _mi_segment_page_alloc(heap, block_size, page_alignment, &heap->tld->segments);
   if (page == NULL) {
@@ -284,6 +284,7 @@ static mi_page_t* mi_page_fresh_alloc(mi_heap_t* heap, mi_page_queue_t* pq, size
   #if MI_HUGE_PAGE_ABANDON
   mi_assert_internal(pq==NULL || _mi_page_segment(page)->page_kind != MI_PAGE_HUGE);
   #endif
+  mi_assert_internal(page_alignment >0 || block_size > MI_MEDIUM_OBJ_SIZE_MAX || _mi_page_segment(page)->kind != MI_SEGMENT_HUGE);
   mi_assert_internal(pq!=NULL || mi_page_block_size(page) >= block_size);
   // a fresh page was found, initialize it
   const size_t full_block_size = (pq == NULL || mi_page_is_huge(page) ? mi_page_block_size(page) : block_size); // see also: mi_segment_huge_page_alloc
@@ -426,6 +427,7 @@ void _mi_page_force_abandon(mi_page_t* page) {
   }
 }
 
+
 // Free a page with no more free blocks
 void _mi_page_free(mi_page_t* page, mi_page_queue_t* pq, bool force) {
   mi_assert_internal(page != NULL);
@@ -449,7 +451,7 @@ void _mi_page_free(mi_page_t* page, mi_page_queue_t* pq, bool force) {
   _mi_segment_page_free(page, force, segments_tld);
 }
 
-#define MI_MAX_RETIRE_SIZE    MI_LARGE_OBJ_SIZE_MAX   // should be less than size for MI_BIN_HUGE
+#define MI_MAX_RETIRE_SIZE    MI_MEDIUM_OBJ_SIZE_MAX   // should be less than size for MI_BIN_HUGE
 #define MI_RETIRE_CYCLES      (16)
 
 // Retire a page with no more used blocks
@@ -623,7 +625,7 @@ static mi_decl_noinline void mi_page_free_list_extend( mi_page_t* const page, co
 #if (MI_SECURE>0)
 #define MI_MIN_EXTEND         (8*MI_SECURE) // extend at least by this many
 #else
-#define MI_MIN_EXTEND         (1)
+#define MI_MIN_EXTEND         (4)
 #endif
 
 // Extend the capacity (up to reserved) by initializing a free list
@@ -632,6 +634,7 @@ static mi_decl_noinline void mi_page_free_list_extend( mi_page_t* const page, co
 // allocations but this did not speed up any benchmark (due to an
 // extra test in malloc? or cache effects?)
 static void mi_page_extend_free(mi_heap_t* heap, mi_page_t* page, mi_tld_t* tld) {
+  MI_UNUSED(tld);
   mi_assert_expensive(mi_page_is_valid_init(page));
   #if (MI_SECURE<=2)
   mi_assert(page->free == NULL);
@@ -640,9 +643,6 @@ static void mi_page_extend_free(mi_heap_t* heap, mi_page_t* page, mi_tld_t* tld)
   #endif
   if (page->capacity >= page->reserved) return;
 
-  size_t page_size;
-  //uint8_t* page_start =
-  _mi_segment_page_start(_mi_page_segment(page), page, &page_size);
   mi_stat_counter_increase(tld->stats.pages_extended, 1);
 
   // calculate the extend count
@@ -688,6 +688,8 @@ static void mi_page_init(mi_heap_t* heap, mi_page_t* page, size_t block_size, mi
   size_t page_size;
   page->page_start = _mi_segment_page_start(segment, page, &page_size);
   mi_track_mem_noaccess(page->page_start,page_size);
+  mi_assert_internal(mi_page_block_size(page) <= page_size);
+  mi_assert_internal(page_size <= page->slice_count*MI_SEGMENT_SLICE_SIZE);
   mi_assert_internal(page_size / block_size < (1L<<16));
   page->reserved = (uint16_t)(page_size / block_size);
   mi_assert_internal(page->reserved > 0);
@@ -702,6 +704,7 @@ static void mi_page_init(mi_heap_t* heap, mi_page_t* page, size_t block_size, mi
     mi_assert_expensive(mi_mem_is_zero(page->page_start, page_size));
   }
   #endif
+  mi_assert_internal(page->is_committed);
   if (block_size > 0 && _mi_is_power_of_two(block_size)) {
     page->block_size_shift = (uint8_t)(mi_ctz((uintptr_t)block_size));
   }
@@ -824,7 +827,7 @@ static mi_page_t* mi_page_queue_find_free_ex(mi_heap_t* heap, mi_page_queue_t* p
   }
 
   if (page == NULL) {
-    _mi_heap_collect_retired(heap, false); // perhaps make a page available
+    _mi_heap_collect_retired(heap, false); // perhaps make a page available?
     page = mi_page_fresh(heap, pq);
     if (page == NULL && first_try) {
       // out-of-memory _or_ an abandoned page with free blocks was reclaimed, try once again
@@ -902,31 +905,47 @@ void mi_register_deferred_free(mi_deferred_free_fun* fn, void* arg) mi_attr_noex
   General allocation
 ----------------------------------------------------------- */
 
-// Huge pages contain just one block, and the segment contains just that page.
+// Large and huge page allocation.
+// Huge pages contain just one block, and the segment contains just that page (as `MI_SEGMENT_HUGE`).
 // Huge pages are also use if the requested alignment is very large (> MI_BLOCK_ALIGNMENT_MAX)
 // so their size is not always `> MI_LARGE_OBJ_SIZE_MAX`.
-static mi_page_t* mi_huge_page_alloc(mi_heap_t* heap, size_t size, size_t page_alignment) {
+static mi_page_t* mi_large_huge_page_alloc(mi_heap_t* heap, size_t size, size_t page_alignment) {
   size_t block_size = _mi_os_good_alloc_size(size);
   mi_assert_internal(mi_bin(block_size) == MI_BIN_HUGE || page_alignment > 0);
+  bool is_huge = (block_size > MI_LARGE_OBJ_SIZE_MAX || page_alignment > 0);
   #if MI_HUGE_PAGE_ABANDON
-  mi_page_queue_t* pq = NULL;
+  mi_page_queue_t* pq = (is_huge ? NULL : mi_page_queue(heap, block_size));
   #else
-  mi_page_queue_t* pq = mi_page_queue(heap, MI_LARGE_OBJ_SIZE_MAX+1);  // always in the huge queue regardless of the block size
-  mi_assert_internal(mi_page_queue_is_huge(pq));
+  mi_page_queue_t* pq = mi_page_queue(heap, is_huge ? MI_LARGE_OBJ_SIZE_MAX+1 : block_size);
+  mi_assert_internal(!is_huge || mi_page_queue_is_huge(pq));
   #endif
   mi_page_t* page = mi_page_fresh_alloc(heap, pq, block_size, page_alignment);
   if (page != NULL) {
-    mi_assert_internal(mi_page_block_size(page) >= size);
     mi_assert_internal(mi_page_immediate_available(page));
-    mi_assert_internal(mi_page_is_huge(page));
-    mi_assert_internal(_mi_page_segment(page)->page_kind == MI_PAGE_HUGE);
-    mi_assert_internal(_mi_page_segment(page)->used==1);
-    #if MI_HUGE_PAGE_ABANDON
-    mi_assert_internal(_mi_page_segment(page)->thread_id==0); // abandoned, not in the huge queue
-    mi_page_set_heap(page, NULL);
-    #endif
-    mi_heap_stat_increase(heap, malloc_huge, mi_page_block_size(page));
-    mi_heap_stat_counter_increase(heap, malloc_huge_count, 1);
+
+    if (is_huge) {
+      mi_assert_internal(mi_page_is_huge(page));
+      mi_assert_internal(_mi_page_segment(page)->kind == MI_SEGMENT_HUGE);
+      mi_assert_internal(_mi_page_segment(page)->used==1);
+      #if MI_HUGE_PAGE_ABANDON
+      mi_assert_internal(_mi_page_segment(page)->thread_id==0); // abandoned, not in the huge queue
+      mi_page_set_heap(page, NULL);
+      #endif
+    }
+    else {
+      mi_assert_internal(!mi_page_is_huge(page));
+    }
+
+    const size_t bsize = mi_page_usable_block_size(page);  // note: not `mi_page_block_size` to account for padding
+    /*if (bsize <= MI_LARGE_OBJ_SIZE_MAX) {
+      mi_heap_stat_increase(heap, malloc_large, bsize);
+      mi_heap_stat_counter_increase(heap, malloc_large_count, 1);
+    }
+    else */
+    {
+      _mi_stat_increase(&heap->tld->stats.malloc_huge, bsize);
+      _mi_stat_counter_increase(&heap->tld->stats.malloc_huge_count, 1);
+    }
   }
   return page;
 }
@@ -937,13 +956,13 @@ static mi_page_t* mi_huge_page_alloc(mi_heap_t* heap, size_t size, size_t page_a
 static mi_page_t* mi_find_page(mi_heap_t* heap, size_t size, size_t huge_alignment) mi_attr_noexcept {
   // huge allocation?
   const size_t req_size = size - MI_PADDING_SIZE;  // correct for padding_size in case of an overflow on `size`
-  if mi_unlikely(req_size > (MI_LARGE_OBJ_SIZE_MAX - MI_PADDING_SIZE) || huge_alignment > 0) {
+  if mi_unlikely(req_size > (MI_MEDIUM_OBJ_SIZE_MAX - MI_PADDING_SIZE) || huge_alignment > 0) {
     if mi_unlikely(req_size > MI_MAX_ALLOC_SIZE) {
       _mi_error_message(EOVERFLOW, "allocation request is too large (%zu bytes)\n", req_size);
       return NULL;
     }
     else {
-      return mi_huge_page_alloc(heap,size,huge_alignment);
+      return mi_large_huge_page_alloc(heap,size,huge_alignment);
     }
   }
   else {

src/prim/unix/prim.c

@@ -409,10 +409,6 @@ static void unix_mprotect_hint(int err) {
   #endif
 }
 
-
-
-
-
 int _mi_prim_commit(void* start, size_t size, bool* is_zero) {
   // commit: ensure we can access the area
   // note: we may think that *is_zero can be true since the memory

src/stats.c

@@ -114,8 +114,8 @@ static void mi_stats_add(mi_stats_t* stats, const mi_stats_t* src) {
   }
   #endif
   for (size_t i = 0; i <= MI_BIN_HUGE; i++) {
-    mi_stat_count_add_mt(&stats->page_bins[i], &src->page_bins[i]);    
-  }  
+    mi_stat_count_add_mt(&stats->page_bins[i], &src->page_bins[i]);
+  }
 }
 
 #undef MI_STAT_COUNT
@@ -314,9 +314,11 @@ static void _mi_stats_print(mi_stats_t* stats, mi_output_fun* out0, void* arg0)
   #endif
   #if MI_STAT
   mi_stat_print(&stats->malloc_normal, "binned", (stats->malloc_normal_count.total == 0 ? 1 : -1), out, arg);
+  // mi_stat_print(&stats->malloc_large, "large", (stats->malloc_large_count.total == 0 ? 1 : -1), out, arg);
   mi_stat_print(&stats->malloc_huge, "huge", (stats->malloc_huge_count.total == 0 ? 1 : -1), out, arg);
   mi_stat_count_t total = { 0,0,0 };
   mi_stat_count_add_mt(&total, &stats->malloc_normal);
+  // mi_stat_count_add(&total, &stats->malloc_large);
   mi_stat_count_add_mt(&total, &stats->malloc_huge);
   mi_stat_print_ex(&total, "total", 1, out, arg, "");
   #endif
@@ -523,7 +525,12 @@ static void mi_heap_buf_print_count_bin(mi_heap_buf_t* hbuf, const char* prefix,
   const size_t binsize = _mi_bin_size(bin);
   const size_t pagesize = (binsize <= MI_SMALL_OBJ_SIZE_MAX ? MI_SMALL_PAGE_SIZE :
                             (binsize <= MI_MEDIUM_OBJ_SIZE_MAX ? MI_MEDIUM_PAGE_SIZE :
-                              (binsize <= MI_LARGE_OBJ_SIZE_MAX ? MI_LARGE_PAGE_SIZE : 0)));
+                              #if MI_LARGE_PAGE_SIZE
+                              (binsize <= MI_LARGE_OBJ_SIZE_MAX ? MI_LARGE_PAGE_SIZE : 0)
+                              #else
+                              0
+                              #endif
+                              ));
   char buf[128];
   _mi_snprintf(buf, 128, "%s{ \"total\": %lld, \"peak\": %lld, \"current\": %lld, \"block_size\": %zu, \"page_size\": %zu }%s\n", prefix, stat->total, stat->peak, stat->current, binsize, pagesize, (add_comma ? "," : ""));
   buf[127] = 0;
@@ -616,7 +623,7 @@ char* mi_stats_get_json(size_t output_size, char* output_buf) mi_attr_noexcept {
   for (size_t i = 0; i <= MI_BIN_HUGE; i++) {
     mi_heap_buf_print_count_bin(&hbuf, "    ", &stats->page_bins[i], i, i!=MI_BIN_HUGE);
   }
-  mi_heap_buf_print(&hbuf, "  ]\n");  
+  mi_heap_buf_print(&hbuf, "  ]\n");
   mi_heap_buf_print(&hbuf, "}\n");
   return hbuf.buf;
 }

test/CMakeLists.txt

@@ -16,7 +16,7 @@ if (NOT CMAKE_BUILD_TYPE)
 endif()
 
 # Import mimalloc (if installed)
-find_package(mimalloc 1.9 CONFIG REQUIRED)
+find_package(mimalloc 2.2 CONFIG REQUIRED)
 message(STATUS "Found mimalloc installed at: ${MIMALLOC_LIBRARY_DIR} (${MIMALLOC_VERSION_DIR})")
 
 

test/main-override-static.c

@@ -10,7 +10,6 @@
 #include <mimalloc.h>
 #include <mimalloc-override.h>  // redefines malloc etc.
 
-static void mi_bins(void);
 
 static void double_free1();
 static void double_free2();
@@ -24,11 +23,12 @@ static void test_reserved(void);
 static void negative_stat(void);
 static void alloc_huge(void);
 static void test_heap_walk(void);
+static void test_heap_arena(void);
+static void test_align(void);
 static void test_canary_leak(void);
 static void test_manage_os_memory(void);
 // static void test_large_pages(void);
 
-
 int main() {
   mi_version();
   mi_stats_reset();
@@ -50,8 +50,10 @@ int main() {
   // negative_stat();
   // test_heap_walk();
   // alloc_huge();
-
-
+  // test_heap_walk();
+  // test_heap_arena();
+  // test_align();
+  
   void* p1 = malloc(78);
   void* p2 = malloc(24);
   free(p1);
@@ -67,7 +69,7 @@ int main() {
   free(p1);
   free(p2);
   free(s);
-
+  
   /* now test if override worked by allocating/freeing across the api's*/
   //p1 = mi_malloc(32);
   //free(p1);
@@ -82,6 +84,13 @@ int main() {
   return 0;
 }
 
+static void test_align() {
+  void* p = mi_malloc_aligned(256, 256);
+  if (((uintptr_t)p % 256) != 0) {
+    fprintf(stderr, "%p is not 256 alignend!\n", p);
+  }
+}
+
 static void invalid_free() {
   free((void*)0xBADBEEF);
   realloc((void*)0xBADBEEF,10);
@@ -239,6 +248,20 @@ static void test_heap_walk(void) {
   mi_heap_visit_blocks(heap, true, &test_visit, NULL);
 }
 
+static void test_heap_arena(void) {
+  mi_arena_id_t arena_id;
+  int err = mi_reserve_os_memory_ex(100 * 1024 * 1024, false /* commit */, false /* allow large */, true /* exclusive */, &arena_id);
+  if (err) abort();
+  mi_heap_t* heap = mi_heap_new_in_arena(arena_id);
+  for (int i = 0; i < 500000; i++) {
+    void* p = mi_heap_malloc(heap, 1024);
+    if (p == NULL) {
+      printf("out of memory after %d kb (expecting about 100_000kb)\n", i);
+      break;
+    }
+  }
+}
+
 static void test_canary_leak(void) {
   char* p = mi_mallocn_tp(char,23);
   for(int i = 0; i < 23; i++) {

test/main-override.cpp

@@ -27,9 +27,12 @@ static void heap_late_free();         // issue #204
 static void padding_shrink();         // issue #209
 static void various_tests();
 static void test_mt_shutdown();
+static void large_alloc(void);        // issue #363
 static void fail_aslr();              // issue #372
 static void tsan_numa_test();         // issue #414
 static void strdup_test();            // issue #445
+static void bench_alloc_large(void);  // issue #xxx
+//static void test_large_migrate(void); // issue #691
 static void heap_thread_free_huge();
 static void test_std_string();        // issue #697
 static void test_thread_local();      // issue #944
@@ -55,18 +58,20 @@ int main() {
   //test_thread_local();
   // heap_thread_free_huge();
   /*
-  heap_thread_free_large();
-  heap_no_delete();
-  heap_late_free();
-  padding_shrink();
+   heap_thread_free_huge();
+   heap_thread_free_large();
+   heap_no_delete();
+   heap_late_free();
+   padding_shrink();
+   various_tests();
+   large_alloc();
+   tsan_numa_test();
+   strdup_test();
+  */
+  // test_stl_allocators();
+  // test_mt_shutdown();
+  // test_large_migrate();
 
-  tsan_numa_test();
-  */
-  /*
-  strdup_test();
-  test_stl_allocators();
-  test_mt_shutdown();
-  */
   //fail_aslr();
   mi_stats_print(NULL);
   return 0;
@@ -358,7 +363,7 @@ static void heap_thread_free_large_worker() {
 
 static void heap_thread_free_large() {
   for (int i = 0; i < 100; i++) {
-    shared_p = mi_malloc_aligned(2*1024*1024 + 1, 8);
+    shared_p = mi_malloc_aligned(2 * 1024 * 1024 + 1, 8);
     auto t1 = std::thread(heap_thread_free_large_worker);
     t1.join();
   }
@@ -369,14 +374,13 @@ static void heap_thread_free_huge_worker() {
 }
 
 static void heap_thread_free_huge() {
-  for (int i = 0; i < 10; i++) {
+  for (int i = 0; i < 100; i++) {
     shared_p = mi_malloc(1024 * 1024 * 1024);
     auto t1 = std::thread(heap_thread_free_huge_worker);
     t1.join();
   }
 }
 
-
 static void test_mt_shutdown()
 {
   const int threads = 5;
@@ -401,6 +405,18 @@ static void test_mt_shutdown()
   std::cout << "done" << std::endl;
 }
 
+// issue #363
+using namespace std;
+
+void large_alloc(void)
+{
+  char* a = new char[1ull << 25];
+  thread th([&] {
+    delete[] a;
+    });
+  th.join();
+}
+
 // issue #372
 static void fail_aslr() {
   size_t sz = (size_t)(4ULL << 40); // 4TiB
@@ -421,6 +437,36 @@ static void tsan_numa_test() {
   t1.join();
 }
 
+// issue #?
+#include <chrono>
+#include <random>
+#include <iostream>
+
+static void bench_alloc_large(void) {
+  static constexpr int kNumBuffers = 20;
+  static constexpr size_t kMinBufferSize = 5 * 1024 * 1024;
+  static constexpr size_t kMaxBufferSize = 25 * 1024 * 1024;
+  std::unique_ptr<char[]> buffers[kNumBuffers];
+
+  std::random_device rd;  (void)rd;
+  std::mt19937 gen(42); //rd());
+  std::uniform_int_distribution<> size_distribution(kMinBufferSize, kMaxBufferSize);
+  std::uniform_int_distribution<> buf_number_distribution(0, kNumBuffers - 1);
+
+  static constexpr int kNumIterations = 2000;
+  const auto start = std::chrono::steady_clock::now();
+  for (int i = 0; i < kNumIterations; ++i) {
+    int buffer_idx = buf_number_distribution(gen);
+    size_t new_size = size_distribution(gen);
+    buffers[buffer_idx] = std::make_unique<char[]>(new_size);
+  }
+  const auto end = std::chrono::steady_clock::now();
+  const auto num_ms = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
+  const auto us_per_allocation = std::chrono::duration_cast<std::chrono::microseconds>(end - start).count() / kNumIterations;
+  std::cout << kNumIterations << " allocations Done in " << num_ms << "ms." << std::endl;
+  std::cout << "Avg " << us_per_allocation << " us per allocation" << std::endl;
+}
+
 
 class MTest
 {
@@ -447,4 +493,4 @@ void test_thread_local()
         mi_stats_print(NULL);
     }
     return;
-}
+}

test/test-stress.c

@@ -320,11 +320,17 @@ int main(int argc, char** argv) {
 
   // Run ITER full iterations where half the objects in the transfer buffer survive to the next round.
   srand(0x7feb352d);
-  // mi_stats_reset();
+  
+  //mi_reserve_os_memory(512ULL << 20, true, true);
+
+  #if !defined(NDEBUG) && !defined(USE_STD_MALLOC)
+  mi_stats_reset();
+  #endif
+
 #ifdef STRESS
-    test_stress();
+  test_stress();
 #else
-    test_leak();
+  test_leak();
 #endif
 
 #ifndef USE_STD_MALLOC