Example profile without this patch: https://perfht.ml/2BwvIvq This profile has many grayed-out rows with threads that don't have any samples.

Comment on attachment 8945924 [details] Bug 1433583 - Discard information about old dead threads that no longer have any samples in the buffer. https://reviewboard.mozilla.org/r/216010/#review222116 ::: tools/profiler/core/ThreadInfo.cpp:28 (Diff revision 1) > int aThreadId, > bool aIsMainThread, > void* aStackTop) > : mName(strdup(aName)) > , mRegisterTime(TimeStamp::Now()) > + , mBufferPositionWhenUnregistered(0) Shouldn't this be UINT64_MAX as that's the "invalid" buffer position marker? ::: tools/profiler/core/platform.cpp:294 (Diff revision 1) > + { > + // Discard any dead threads that were unregistered before aBufferRangeStart. > + ThreadVector& deadThreads = sInstance->mDeadThreads; > + for (size_t i = 0; i < deadThreads.size(); i++) { > + if (deadThreads.at(i)->BufferPositionWhenUnregistered() < aBufferRangeStart) { > + delete deadThreads.at(i); This manual memory management is a bit unfortunate - it'd be nicer if we could have a vector of UniquePtr<T>s instead. This is fine though & that change should probably be done separately if at all.

Comment on attachment 8945924 [details] Bug 1433583 - Discard information about old dead threads that no longer have any samples in the buffer. https://reviewboard.mozilla.org/r/216010/#review222116 > Shouldn't this be UINT64_MAX as that's the "invalid" buffer position marker? The value of this field wouldn't be used unless the thread was unregistered (at which point it would have a good value), but this wasn't enforced by the code. I've changed this field to a Maybe. > This manual memory management is a bit unfortunate - it'd be nicer if we could have a vector of UniquePtr<T>s instead. > > This is fine though & that change should probably be done separately if at all. I agree. I've filed bug 1434440 about it.

Pushed by mstange@themasta.com: https://hg.mozilla.org/integration/autoland/rev/dff05b1676b1 Discard information about old dead threads that no longer have any samples in the buffer. r=mystor