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PoC: feat(profiling): add heap-live profiling for memory leak detection#3623

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PoC: feat(profiling): add heap-live profiling for memory leak detection#3623
realFlowControl wants to merge 3 commits intomasterfrom
florian/heap-live-profiling

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@realFlowControl realFlowControl commented Feb 4, 2026 •
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Warning

do not merge, this is PoC

Description

Track allocations that survive across profile exports using heap-live-samples and heap-live-size sample types. Samples are emitted in batches at export time.

Enable via DD_PROFILING_HEAP_LIVE_ENABLED or datadog.profiling.heap_live_enabled (default disabled), only works when allocation profiling is active.

Reviewer checklist

  • Test coverage seems ok.
  • Appropriate labels assigned.

PROF-13688

@github-actions github-actions bot added the profiling Relates to the Continuous Profiler label Feb 4, 2026
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datadog-official bot commented Feb 4, 2026 •
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⚠️ Tests

✨ Fix all issues with Cursor

⚠️ Warnings

🧪 1028 Tests failed

    ❄️ Known flaky: Endpoints are sent() from com.datadog.appsec.php.integration.Laravel8xTests (Fix with Cursor)

    ❄️ Known flaky: Endpoints are sent() from com.datadog.appsec.php.integration.Symfony62Tests (Fix with Cursor)

testSearchPhpBinaries from integration.DDTrace\Tests\Integration\PHPInstallerTest (Datadog) (Fix with Cursor) 
DDTrace\Tests\Integration\PHPInstallerTest::testSearchPhpBinaries
Test code or tested code printed unexpected output: Searching for available php binaries, this operation might take a while.
View all

ℹ️ Info

❄️ No new flaky tests detected

This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 91f9d71 | Docs | Datadog PR Page | Was this helpful? Give us feedback!

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pr-commenter bot commented Feb 4, 2026 •
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Benchmarks [ profiler ]

Benchmark execution time: 2026-02-12 08:02:42

Comparing candidate commit 91f9d71 in PR branch florian/heap-live-profiling with baseline commit de9c414 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 27 metrics, 9 unstable metrics.

@realFlowControl realFlowControl force-pushed the florian/heap-live-profiling branch from bc087f2 to 817465a Compare February 4, 2026 21:03
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codecov-commenter commented Feb 4, 2026 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.20%. Comparing base (de9c414) to head (91f9d71).

Additional details and impacted files

Impacted file tree graph

@@            Coverage Diff             @@
##           master    #3623      +/-   ##
==========================================
+ Coverage   62.11%   62.20%   +0.08%     
==========================================
  Files         141      141              
  Lines       13387    13387              
  Branches     1753     1753              
==========================================
+ Hits         8315     8327      +12     
+ Misses       4273     4263      -10     
+ Partials      799      797       -2

see 2 files with indirect coverage changes

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pr-commenter bot commented Feb 5, 2026 •
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Benchmarks [ tracer ]

Benchmark execution time: 2026-02-06 08:47:53

Comparing candidate commit 49b5835 in PR branch florian/heap-live-profiling with baseline commit 6843f96 in branch master.

Found 1 performance improvements and 4 performance regressions! Performance is the same for 186 metrics, 3 unstable metrics.

scenario:ComposerTelemetryBench/benchTelemetryParsing

  • 🟩 execution_time [-1.897µs; -1.103µs] or [-14.823%; -8.614%]

scenario:SamplingRuleMatchingBench/benchRegexMatching1

  • 🟥 execution_time [+112.809ns; +149.391ns] or [+9.856%; +13.052%]

scenario:SamplingRuleMatchingBench/benchRegexMatching2

  • 🟥 execution_time [+102.670ns; +152.930ns] or [+8.935%; +13.309%]

scenario:SamplingRuleMatchingBench/benchRegexMatching3

  • 🟥 execution_time [+76.869ns; +117.931ns] or [+6.586%; +10.105%]

scenario:SamplingRuleMatchingBench/benchRegexMatching4

  • 🟥 execution_time [+108.622ns; +151.178ns] or [+9.463%; +13.171%]

@realFlowControl realFlowControl force-pushed the florian/heap-live-profiling branch 5 times, most recently from 4aaffbf to 540cc19 Compare February 10, 2026 15:22
@realFlowControl realFlowControl mentioned this pull request Feb 10, 2026
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@realFlowControl realFlowControl force-pushed the florian/heap-live-profiling branch 2 times, most recently from 0ecb066 to 79ff80d Compare February 11, 2026 17:55
realFlowControl and others added 3 commits February 12, 2026 08:19
@realFlowControl @claude
feat(profiling): add heap-live profiling for memory leak detection
1712f68 
Track allocations that survive across profile exports using heap-live-samples
and heap-live-size sample types. Samples are emitted in batches at export time.

Enabled via DD_PROFILING_HEAP_LIVE_ENABLED when allocation profiling is active.

Co-Authored-By: Claude Opus 4.5 <[email protected]>
@realFlowControl @claude
refactor(profiling): simplify heap-live and sample filter code
9867f1e 
- Use functional style (map + match) in collect_batched_heap_live_samples
- Only create ProfileIndex when heap-live tracking is enabled
- Replace 32 repetitive I/O profiling lines with a loop
- Use filter_map in sample type filter method
- Add early bail-out in free_allocation when heap-live is disabled

Co-Authored-By: Claude Opus 4.5 <[email protected]>
@realFlowControl @claude
perf(profiling): use fast pointer hasher for heap-live tracker
91f9d71 
Replace default SipHash with a simple bit-mixing hasher optimized for
pointer addresses. Since pointers are already well-distributed, we use
`ptr ^ (ptr >> 4)` instead of expensive cryptographic hashing.

This reduces overhead in untrack_allocation() which is called on every free.

Co-Authored-By: Claude Opus 4.5 <[email protected]>
@realFlowControl realFlowControl force-pushed the florian/heap-live-profiling branch 2 times, most recently from d87cdf9 to 91f9d71 Compare February 12, 2026 07:46
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