Thanks a lot! We'll try to profile what is going on, I'll let you know if we
find something.Skipping locks if possible is always nice. I'll look into
getting collection approach.
Eugene
> Subject: Re: [lldb-dev] How to enumerate stopped threads in C++ API?
> From: gclay...@apple.com
> Date: Thu, 3 Mar 2016 12:41:16 -0800
> CC: lldb-dev@lists.llvm.org; rd...@microsoft.com
> To: eugen...@hotmail.com
>
> Each call into the lldb::SB* API will take a target lock and possible a
> process read/write lock.
>
> We do have a SBThreadCollection class that we can use. Feel free to add an
> API like this to SBProcess:
>
>
> class SBProcess
> {
> SBThreadCollection GetThreads();
> };
>
> class SBThreadCollection
> {
> SBThreadCollection GetThreadsWithStopReasons();
> };
>
>
> The current API on process SBProcess::GetNumThreads() and
> SBProcess::GetThreadAtIndex() might have issues if you are doing things like
> evaluating an expression on another thread where you might request the number
> of threads and get 10, but then an expression runs on another thread and
> there are now maybe 8 or 12 threads, and then you call
> SBProcess::GetThreadAtIndex() and it might return you results that are
> different that what you wanted. If we return all threads at once, we won't
> run into this issue. Then you can have SBThreadCollection add a new methods
> to return a new list for all threads with stop reasons.
>
> That being said, hundreds of threads should not cause a huge bottleneck for
> single stop, but if you doing it many many many times it could be.
>
> Greg Clayton
>
> > On Mar 3, 2016, at 9:54 AM, Eugene Birukov via lldb-dev
> > <lldb-dev@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
> >
> >
> > _______________________________________________
> > lldb-dev mailing list
> > lldb-dev@lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>
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