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feat(prof): optimise allocation profiling for PHP >= 8.4#3550

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morrisonlevi merged 15 commits intomasterfrom
florian/alloc-php-84
Jan 16, 2026
Merged

feat(prof): optimise allocation profiling for PHP >= 8.4#3550
morrisonlevi merged 15 commits intomasterfrom
florian/alloc-php-84

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@realFlowControl realFlowControl commented Dec 27, 2025 •
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Description

Since #3360 and with #3361 we've disabled the code path for PHP 8.4's zend_mm_set_custom_handlers_ex(). This PR re-enables that code path again bringing down overhead for allocation profiling.

This uses the same approach as PHP <= 8.3 allocation profiling with the difference that for alloc(), realloc() and free() calls we do not "prepare" the ZendMM heap by manipulating the heap->use_custom_heap flag anymore. This was necessary for when the allocation fails, ZendMM might call zend_mm_gc() to try and free memory for a new chunk which would just return 0; in case a custom allocator is installed.

With us being able to hook into zend_mm_gc() we can stop manipulating the heap->use_custom_heap flag in the allocator hot path and only do so in case a zend_mm_gc() was triggered.

Additionally this adds a prof correctness test with a custom allocator being used by setting USE_ZEND_ALLOC=0 but validating against the JSON that we use for allocation profiling correctness -> even with a custom allocator we should emit the same profile as without.

Reviewer checklist

  • Test coverage seems ok.
  • Appropriate labels assigned.

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codecov-commenter commented Dec 27, 2025 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.92%. Comparing base (7ae15a5) to head (3ca8f0e).
⚠️ Report is 190 commits behind head on master.

Additional details and impacted files

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@@            Coverage Diff             @@
##           master    #3550      +/-   ##
==========================================
- Coverage   62.01%   61.92%   -0.10%     
==========================================
  Files         140      140              
  Lines       13309    13309              
  Branches     1762     1762              
==========================================
- Hits         8253     8241      -12     
- Misses       4268     4278      +10     
- Partials      788      790       +2

see 2 files with indirect coverage changes

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pr-commenter Bot commented Dec 27, 2025 •
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Benchmarks [ profiler ]

Benchmark execution time: 2026-01-16 23:23:05

Comparing candidate commit 3ca8f0e in PR branch florian/alloc-php-84 with baseline commit 7ae15a5 in branch master.

Found 0 performance improvements and 1 performance regressions! Performance is the same for 29 metrics, 6 unstable metrics.

scenario:php-profiler-timeline-memory-with-profiler-and-timeline

  • 🟥 execution_time [+27.176ms; +50.093ms] or [+2.211%; +4.075%]

@realFlowControl realFlowControl force-pushed the florian/alloc-php-84 branch 2 times, most recently from 4e8b1eb to b061348 Compare January 13, 2026 12:54
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datadog-official Bot commented Jan 13, 2026 •
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⚠️ Tests

✨ Fix all issues with Cursor

⚠️ Warnings

🧪 1022 Tests failed

    testSearchPhpBinaries from integration.DDTrace\Tests\Integration\PHPInstallerTest (Fix with Cursor)

    testSimplePushAndProcess from laravel-58-test.DDTrace\Tests\Integrations\Laravel\V5_8\QueueTest (Fix with Cursor)

testSimplePushAndProcess from laravel-8x-test.DDTrace\Tests\Integrations\Laravel\V8_x\QueueTest (Datadog) (Fix with Cursor) 
DDTrace\Tests\Integrations\Laravel\V8_x\QueueTest::testSimplePushAndProcess
Test code or tested code printed unexpected output: spanLinksTraceId: 696ac637000000000fcd4089ba98eb42
tid: 696ac63700000000
hexProcessTraceId: 0fcd4089ba98eb42
hexProcessSpanId: 6c180d766aae3125
processTraceId: 1138637241079884610
processSpanId: 7788990357784375589

phpvfscomposer://tests/vendor/phpunit/phpunit/phpunit:106
View all

ℹ️ Info

❄️ No new flaky tests detected

This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 3ca8f0e | Docs | Datadog PR Page | Was this helpful? Give us feedback!

@realFlowControl realFlowControl force-pushed the florian/alloc-php-84 branch 2 times, most recently from c24208c to 1653fa2 Compare January 13, 2026 14:01
@realFlowControl realFlowControl marked this pull request as ready for review January 14, 2026 10:28
@realFlowControl realFlowControl requested review from a team as code owners January 14, 2026 10:28
@realFlowControl realFlowControl changed the title fix(prof): allocation profiling for PHP 8.4 feat(prof): allocation profiling for PHP 8.4 Jan 16, 2026
@realFlowControl realFlowControl changed the title feat(prof): allocation profiling for PHP 8.4 feat(prof): optimise allocation profiling for PHP >= 8.4 Jan 16, 2026
@realFlowControl realFlowControl mentioned this pull request Jan 16, 2026
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morrisonlevi
morrisonlevi approved these changes Jan 16, 2026
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I merged in master to fix the merge conflict. Looks good. Hopefully no other weird edges pop up on 8.4+ and the API works as intended.

@morrisonlevi morrisonlevi merged commit 1316514 into master Jan 16, 2026
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@morrisonlevi morrisonlevi deleted the florian/alloc-php-84 branch January 16, 2026 23:48
@github-actions github-actions Bot added this to the 1.16.0 milestone Jan 16, 2026
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