[lldb-dev] [PATCH] make dosep.ty test driver multi-threadable

[Ed Maste]

>> Maybe "@serializeTest"?
>
> That's worth a try.

I have a slight worry that this approach could mask real concurrency
issues in LLDB itself; if we know that the issues are only in the test
code it seems more reasonable.  Even in that case though tests could
run concurrently on the same machine, e.g. a buildbot host that builds
and tests multiple configurations.

> In the event that your idea works out to eliminate those failures, there is another element we can consider.  We can have Python give us the # cores available (if there's something portable to do that), and when not otherwise specified, pick a reasonable default # threads to get decent test run performance without needing the environment  variable specified.  This would give anybody running the tests a decent test run speedup without having to read docs on configuring the environment variable.  (I think this was Steve Pucci's idea but definitely something we discussed.)

I was going to make that suggestion too.  Python does have a portable
way to get the core count:

>>> import multiprocessing
>>> multiprocessing.cpu_count()
8

Anyhow, explicitly serializing the tests that intermittently fail
would be no worse than today, and worth it to improve the cycle time.