Merge branch 'dev-slice' into dev-slice-cmask

include/mimalloc-internal.h

@@ -63,6 +63,7 @@ static inline uintptr_t _mi_random_shuffle(uintptr_t x);
 extern mi_decl_cache_align mi_stats_t       _mi_stats_main;
 extern mi_decl_cache_align const mi_page_t  _mi_page_empty;
 bool       _mi_is_main_thread(void);
+size_t     _mi_current_thread_count(void);
 bool       _mi_preloading(void);  // true while the C runtime is not ready
 
 // os.c

src/init.c

@@ -359,6 +359,12 @@ bool _mi_is_main_thread(void) {
   return (_mi_heap_main.thread_id==0 || _mi_heap_main.thread_id == _mi_thread_id());
 }
 
+static _Atomic(uintptr_t) thread_count = ATOMIC_VAR_INIT(1);
+
+size_t  _mi_current_thread_count(void) {
+  return mi_atomic_load_relaxed(&thread_count);
+}
+
 // This is called from the `mi_malloc_generic`
 void mi_thread_init(void) mi_attr_noexcept
 {
@@ -371,6 +377,7 @@ void mi_thread_init(void) mi_attr_noexcept
   if (_mi_heap_init()) return;  // returns true if already initialized
 
   _mi_stat_increase(&_mi_stats_main.threads, 1);
+  mi_atomic_increment_relaxed(&thread_count);
   //_mi_verbose_message("thread init: 0x%zx\n", _mi_thread_id());
 }
 
@@ -379,6 +386,7 @@ void mi_thread_done(void) mi_attr_noexcept {
 }
 
 static void _mi_thread_done(mi_heap_t* heap) {
+  mi_atomic_decrement_relaxed(&thread_count);
   _mi_stat_decrease(&_mi_stats_main.threads, 1);
 
   // check thread-id as on Windows shutdown with FLS the main (exit) thread may call this on thread-local heaps...

src/segment.c

@@ -790,7 +790,7 @@ static mi_segment_t* mi_segment_init(mi_segment_t* segment, size_t required, mi_
   const size_t segment_size = segment_slices * MI_SEGMENT_SLICE_SIZE;
 
   // Commit eagerly only if not the first N lazy segments (to reduce impact of many threads that allocate just a little)
-  const bool eager_delay = (!_mi_is_main_thread() && tld->count < (size_t)mi_option_get(mi_option_eager_commit_delay));
+  const bool eager_delay = (_mi_current_thread_count() > 4 && tld->count < (size_t)mi_option_get(mi_option_eager_commit_delay));
   const bool eager = !eager_delay && mi_option_is_enabled(mi_option_eager_commit);
   bool commit = eager || (required > 0);