[lldb] Create dependent modules in parallel (#114507) #9508
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In [D148380](https://reviews.llvm.org/D148380), Alex added locking to PathMappingLists. The current implementation runs the callback under the lock, which I don't believe is necessary. As far as I can tell, no users of the callback are relying on the list not having been modified until the callback is handled. This patch implements my suggestion to unlock the mutex before the callback. I also switched to a non-recursive mutex as I don't believe the recursive property is needed. To make the class fully thread safe, I did have to introduce another mutex to protect the callback members. The motivation for this change is llvm#114507. Specifically, Target::SetExecutableModule calls Target::GetOrCreateModule, which potentially performs path remapping, which in turns has a callback to Target::SetExecutableModule. (cherry picked from commit 8f8e2b7)
Create dependent modules in parallel in Target::SetExecutableModule. This change was inspired by llvm#110646 which takes the same approach when attaching. Jason suggested we could use the same approach when you create a target in LLDB. I used Slack for benchmarking, which loads 902 images. ``` Benchmark 1: ./bin/lldb /Applications/Slack.app/Contents/MacOS/Slack Time (mean ± σ): 1.225 s ± 0.003 s [User: 3.977 s, System: 1.521 s] Range (min … max): 1.220 s … 1.229 s 10 runs Benchmark 2: ./bin/lldb /Applications/Slack.app/Contents/MacOS/Slack Time (mean ± σ): 3.253 s ± 0.037 s [User: 3.013 s, System: 0.248 s] Range (min … max): 3.211 s … 3.310 s 10 runs ``` We see about a 2x speedup, which matches what Jason saw for the attach scenario. I also ran this under TSan to confirm this doesn't introduce any races or deadlocks. (cherry picked from commit a57296a)
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Create dependent modules in parallel in Target::SetExecutableModule.
This change was inspired by llvm#110646 which takes the same approach when
attaching. Jason suggested we could use the same approach when you
create a target in LLDB.
I used Slack for benchmarking, which loads 902 images.
We see about a 2x speedup, which matches what Jason saw for the attach
scenario. I also ran this under TSan to confirm this doesn't introduce
any races or deadlocks.