Fix misuses of CopyOnWriteArrayList
#4247
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lcian
requested review from
adinauer,
romtsn,
stefanosiano and
markushi
as code owners
lcian
commented
Mar 10, 2025
| @@ -155,7 +154,10 @@ private void onDeadlineTimeoutReached() { | |||
| // abort all child-spans first, this ensures the transaction can be finished, | |||
| // even if waitForChildren is true | |||
| // iterate in reverse order to ensure leaf spans are processed before their parents | |||
| @NotNull final ListIterator<Span> iterator = children.listIterator(children.size()); | |||
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This is not thread safe, the list could change size after we create the iterator
lcian
commented
Mar 10, 2025
Comment on lines
+158
to
+160
| while (iterator.hasNext()) { | ||
| iterator.next(); | ||
| } |
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Need to do it this way as there's no other way to get a reverse iterator in a thread-safe manner
Performance metrics 🚀
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lcian
changed the title
SentryTracer.childrenCopyOnWriteArrayList
|
Only found another occurrence where we are misusing |
lcian
commented
Mar 10, 2025
| return new CopyOnWriteArrayList<>(attachments); | ||
| return attachments; |
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It is not necessary to copy here, as we are already using a CopyOnWriteArrayList
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📜 Description
CopyOnWriteArrayListallows us to access its elements without copying and without the possibility to cause aConcurrentModificationException.This PR modifies its usages so that we avoid copying in order to get better performance memory-wise.
We also make sure that we are using it correctly to avoid other issues (using the iterator to avoid a possible NPE that could happen with index-based accesses, and other cases where we do things that are not thread safe).
💡 Motivation and Context
Closes #2815
💚 How did you test it?
Tested as documented in #2815 (comment)
📝 Checklist
sendDefaultPIIis enabled.