fix: Profiling memory leaks #3055
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Passing the std::function (which captures the `SentryProfilingState`) to the thread constructor creates a copy of the std::function that appears to not be destructed when the thread exits - unclear if this is expected behavior, but passing it as a const ref instead of a copy fixes the leak.
This is the same fix as the other leak fix, for the same reason - std::thread leaks the parameters even after the thread exits
indragiek
requested review from
philipphofmann,
brustolin and
armcknight
as code owners
Closed
indragiek
commented
May 24, 2023
| }; | ||
| NSString *const labelNSStr = | ||
| [NSString stringWithUTF8String:backtrace.queueMetadata.label->c_str()]; | ||
| // -[NSString stringWithUTF8String:] can return `nil` for malformed string data |
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Here's a repro of this happening:
Codecov Report
Additional details and impacted files@@ Coverage Diff @@
## main #3055 +/- ##
=============================================
+ Coverage 88.844% 88.865% +0.021%
=============================================
Files 492 492
Lines 52976 53017 +41
Branches 18970 18992 +22
=============================================
+ Hits 47066 47114 +48
+ Misses 4953 4948 -5
+ Partials 957 955 -2
... and 10 files with indirect coverage changes Continue to review full report in Codecov by Sentry.
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Performance metrics 🚀
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| Revision | Plain | With Sentry | Diff |
|---|---|---|---|
| 2af280d | 1219.33 ms | 1239.98 ms | 20.65 ms |
| 1bbcb9c | 1189.61 ms | 1223.50 ms | 33.89 ms |
| 1db04d8 | 1250.20 ms | 1258.12 ms | 7.92 ms |
| 0001a09 | 1223.90 ms | 1249.56 ms | 25.66 ms |
| 8526e93 | 1228.24 ms | 1239.14 ms | 10.90 ms |
| c0b4b71 | 1218.16 ms | 1251.28 ms | 33.12 ms |
| 8f397a7 | 1196.55 ms | 1226.82 ms | 30.27 ms |
| bd2afa6 | 1192.31 ms | 1210.37 ms | 18.05 ms |
| ecd9ecd | 1191.76 ms | 1216.92 ms | 25.16 ms |
| 1bf8571 | 1215.31 ms | 1232.48 ms | 17.17 ms |
App size
| Revision | Plain | With Sentry | Diff |
|---|---|---|---|
| 2af280d | 20.76 KiB | 435.22 KiB | 414.46 KiB |
| 1bbcb9c | 20.76 KiB | 426.10 KiB | 405.34 KiB |
| 1db04d8 | 20.76 KiB | 435.50 KiB | 414.74 KiB |
| 0001a09 | 20.76 KiB | 433.19 KiB | 412.43 KiB |
| 8526e93 | 20.76 KiB | 420.22 KiB | 399.47 KiB |
| c0b4b71 | 20.76 KiB | 430.98 KiB | 410.22 KiB |
| 8f397a7 | 20.76 KiB | 420.55 KiB | 399.79 KiB |
| bd2afa6 | 20.76 KiB | 420.55 KiB | 399.79 KiB |
| ecd9ecd | 20.76 KiB | 420.23 KiB | 399.47 KiB |
| 1bf8571 | 20.76 KiB | 437.12 KiB | 416.36 KiB |
philipphofmann
approved these changes
May 24, 2023
armcknight
approved these changes
May 24, 2023
| @@ -107,8 +107,8 @@ namespace profiling { | |||
| } | |||
| isSampling_ = true; | |||
| numSamples_ = 0; | |||
| thread_ = std::thread(samplingThreadMain, port_, clock_, delaySpec_, cache_, callback_, | |||
| std::ref(numSamples_), onThreadStart); | |||
| thread_ = std::thread(samplingThreadMain, port_, clock_, delaySpec_, std::cref(cache_), | |||
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TIL std::ref and std::cref, nice! I was trying to do this with & which wouldn't compile 😭
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📜 Description
This fixes most of the memory leaks reported in #2980. I checked before/after the fixes using Instruments.
Before:
After:
There is 1 memory leak left to fix that I couldn't find a solution for yet, but the other leaks are fixed.
The root of the problem seems to be that
std::threaddoes not correctly deallocate parameters that are passed to the newly spawned thread. It's unclear if this is expected behavior or not, but the fix was simple: pass parameters that were being copied (and leaked) by reference.There's also one more unrelated fix to a crash that I found while debugging the leaks - it turns out
-[NSString stringWithUTF8String:]can returnnilfor malformed data and we weren't checking for nil.💚 How did you test it?
Check before/after the fix in Instruments, run all existing unit tests.
📝 Checklist
You have to check all boxes before merging:
sendDefaultPIIis enabled.🔮 Next steps