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Pass surviving descriptor through jemalloc_postfork_child orchestrator

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The orchestrator looks up the surviving descriptor via
tcache_postfork_arena_descriptor and threads it into
arena_postfork_child, eliminating arena's call into tcache. Also reset
cache_bin_array_descriptor_ql_mtx right before the queue rebuild it
protects.
This commit is contained in:
Slobodan Predolac 2026-05-08 11:36:12 -07:00
parent 3cd9753e23
commit 88745978e9
5 changed files with 28 additions and 23 deletions
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19
src/arena.c
View file

@ -271,10 +271,9 @@ arena_cache_bin_array_unregister(tsdn_t *tsdn, arena_t *arena,
}
/*
* Postfork-child entry: child is single-threaded and the queue is rebuilt
* from scratch (descriptors held by other threads at fork time are gone).
* The mutex itself is reinitialized later in arena_postfork_child, so we
* cannot lock here.
* Postfork-child entry: child is single-threaded, so the queue is rebuilt
* from scratch (descriptors held by other threads at fork time are gone)
* without locking.
*/
void
arena_cache_bin_array_postfork_child(arena_t *arena,
@ -2160,7 +2159,8 @@ arena_postfork_parent(tsdn_t *tsdn, arena_t *arena) {
}
void
arena_postfork_child(tsdn_t *tsdn, arena_t *arena) {
arena_postfork_child(tsdn_t *tsdn, arena_t *arena,
cache_bin_array_descriptor_t *surviving_desc) {
atomic_store_u(&arena->nthreads[0], 0, ATOMIC_RELAXED);
atomic_store_u(&arena->nthreads[1], 0, ATOMIC_RELAXED);
if (tsd_arena_get(tsdn_tsd(tsdn)) == arena) {
@ -2169,7 +2169,11 @@ arena_postfork_child(tsdn_t *tsdn, arena_t *arena) {
if (tsd_iarena_get(tsdn_tsd(tsdn)) == arena) {
arena_nthreads_inc(arena, true);
}
tcache_arena_postfork_child(tsdn, arena);
if (config_stats) {
malloc_mutex_postfork_child(tsdn,
&arena->cache_bin_array_descriptor_ql_mtx);
arena_cache_bin_array_postfork_child(arena, surviving_desc);
}
for (unsigned i = 0; i < nbins_total; i++) {
JEMALLOC_SUPPRESS_WARN_ON_USAGE(
@ -2179,7 +2183,4 @@ arena_postfork_child(tsdn_t *tsdn, arena_t *arena) {
malloc_mutex_postfork_child(tsdn, &arena->large_mtx);
base_postfork_child(tsdn, arena->base);
pa_shard_postfork_child(tsdn, &arena->pa_shard);
if (config_stats) {
malloc_mutex_postfork_child(tsdn, &arena->cache_bin_array_descriptor_ql_mtx);
}
}