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Stdlib: memory_get_usage()/memory_get_peak_usage() real_usage peaks must dominate emalloc (zend_alloc.c) #4933
Description
Category
stdlib
Problem
When real_usage=true, Zend reports malloc/system memory (RSS / zend_mm_heap real size). The emalloc subset (real_usage=false) is always ≤ the real peak in normal processes.
VmMemory currently uses RSS for both code paths (readEmallocApprox() calls readRssBytes()), so peaks are tracked in separate counters from the same source and ordering breaks:
memory_get_usage(true) >= memory_get_usage(false); // Zend: true
memory_get_peak_usage(true) >= memory_get_peak_usage(false); // Zend: trueVM today prints false for both comparisons (maintainer probe 2026-06-03).
Distinct from broad tracker #3280 (stdlib introspection batch) — this is the real_usage vs emalloc semantics bug in VmMemory / phpc_memory.c.
php-src reference
- php/php-src
ext/standard/basic_functions.c—zif_memory_get_usage,zif_memory_get_peak_usage - php/php-src
Zend/zend_alloc.c—zend_mm_get_custom_size,zend_mm_get_real_size
Repro
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro-maintainer/memory_real_usage_order.php
php bin/vm.php test/repro-maintainer/memory_real_usage_order.php'| Check | Zend PHP 8.2 | bin/vm.php |
|---|---|---|
memory_get_usage(true) >= memory_get_usage(false) |
true |
false |
memory_get_peak_usage(true) >= memory_get_peak_usage(false) |
true |
false |
Scope
| Path | Notes |
|---|---|
ext/standard/VmMemory.php |
stop conflating emalloc peak with RSS |
lib/AOT/runtime/phpc_memory.c |
mirror Zend dual counters for AOT |
| Tests | test/compliance/cases/stdlib/memory_real_usage_order.phpt |
Done when
-
real_usage=falseuses emalloc/custom heap approximation (not RSS) -
real_usage=trueuses RSS /zend_mmreal size - Peak counters satisfy
real >= emallocafter warm-up calls -
./script/ci-fast.sh --filter memory_real_usage_ordergreen
Related
- Stdlib: memory_get_usage() / memory_get_peak_usage() / gc_status() — runtime introspection (ext/standard parity) #3280, Bootstrap: memory_get_usage()/memory_get_peak_usage() — native counters without host Zend (basic_functions.c) #4862, Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492
Activity
PurHur commentedon Jun 3, 2026
Repro script (add under
test/repro-maintainer/)```php
=emalloc: ', ($ur >= $u ? 'true' : 'false'), PHP_EOL; echo 'peak real>=emalloc: ', ($pur >= $pu ? 'true' : 'false'), PHP_EOL; \`\`\` Zend prints both `true`; VM currently prints both `false` when `VmMemory` maps both paths to RSS.PurHur commentedon Jul 12, 2026
claim: worker-lane-b — starting this run
PurHur commentedon Jul 12, 2026
claim released: repro green on master — both
memory_get_usage(true) >= memory_get_usage(false)and peak ordering return true on VM (Docker php-env). VmMemory already uses MemoryAccounting for emalloc and RSS for real_usage. Pivoting.PurHur commentedon Jul 17, 2026
claim: worker-lane-b — verifying prior fix / closing if green
Trust gates (master):
php script/bootstrap-inventory.php --check→ OK 5310/5310./script/release-readiness.sh --json→user_release_ready: yes(inventory, spine, north-star5-fast, vm-driver-probe all ok)Repro (Docker
php-env):Inline probe matches prior release comment (2026-07-12):
VmMemoryalready separates emalloc vs RSS. Closing as done.PurHur commentedon Jul 17, 2026
Closed: done-when already met on master (no PR needed).
Verified 2026-07-17 in Docker:
memory_get_usage(true) >= memory_get_usage(false)→ true (VM + Zend)memory_get_peak_usage(true) >= memory_get_peak_usage(false)→ true (VM + Zend)Prior worker note (2026-07-12) was correct — dual counters via MemoryAccounting/RSS.