[lldb-dev] How to enumerate stopped threads in C++ API?

Jim Ingham via lldb-dev lldb-dev at lists.llvm.org
Thu Mar 3 12:17:06 PST 2016

I'm surprised that this turns out to be a bottleneck.  All the work to create the threads should have been done when you stopped, so this should just be running over a vector that already exists and pulling a field out.  Can you profile this and see what is actually slow?


> On Mar 3, 2016, at 9:54 AM, Eugene Birukov via lldb-dev <lldb-dev at lists.llvm.org> wrote:
> Hi,
> I am working on a custom debugger on Linux and I am using LLDB C++ API for that. So far, from the functionality point of view the life is good, but I am running into severe performance issue.
> The problem is that the target application has literally hundreds of threads, and when the target process stops, I need to identify all the threads that have non-trivial stop reason. So, I am doing something like that:
>     // Loop over threads
>     int numThreads = m_Process.GetNumThreads();
>     for (int threadIndex = 0; threadIndex < numThreads; ++threadIndex)
>     {
>         // Inspect the thread state
>         sbThread = m_Process.GetThreadAtIndex(threadIndex);
>         stopReason = sbThread.GetStopReason();
> ...
> Well, this loop turns out to be a bottleneck. 
> So, is there any way to find all the stopped threads without iterating over the whole world?
> Thanks,
> Eugene
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