[lldb-dev] OS X and parallel test framework issue

[Todd Fiala]

Hi all,

Anybody have any thoughts on this
bug<http://llvm.org/bugs/show_bug.cgi?id=19575>?
 I spent some time over the weekend tracking down why the LLDB parallelized
test running infrastructure is not speeding up OS X test runs.  What I saw
essentially looked like critical section-like behavior somewhere in the
chain of python running the worker thread's 'system' call to the real unit
test python code.

It's as if one of these is serializing calls across all threads on my OS X
10.9 setup:
* python system call to launch unit tests
* python unit testing framework
* lldb python module
* lldb innards

On my system I have 8 threads all ready to do the python system call in the
worker thread but only one is progressing at a time.  By contrast, on my
Linux setup I can get 32 of these to happen simultaneously with no blockage.

Any thoughts?  See the bug for some extra logging I added that will show
what each worker thread is doing and when it's ready to try to run an
underlying test.

Thanks!  Getting this resolved should reduce OS X test run times
significantly based on # cores available.
-- 
Todd Fiala | Software Engineer | tfiala at google.com | 650-943-3180
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