We have many tests that create 100 threads or more, and mounting evidence that
this is harmful to our CI environment.
When the original code for many of these tests was written we ran our tests
under run_tests, which had explicit handling for tracking the number of threads
each test needed and making sure that we weren't over subscribing the test
runner. Bazel has no such facility (and the facility in run_tests has since
been removed) and so we need to adjust.
This PR adjusts down a single test and is part of a series so that we can
review and roll back easily if required.
This is a partial fork of the windows iomgr code - specifically the IOCP and Socket pieces - with some improved architecture and encapsulation. And the start of a WindowsEventEngine.
Once this code is used in a gRPC TCP context, I imagine a few issues will shake out. Also, getting sanitizers set up with MSVC will take a bit of work (see a commit referencing abseil and MSVC bugs to hack around).
I forked the IomgrEventEngine's posix poller interfaces in the hope of negotiating compatibility between the platforms, but the interfaces diverged a fair bit, and I'm doubtful we'll be able to use these "pollers" generically in the same TCP code. Reunification might not happen, and that's probably fine, we'll see how similar the TCP code looks once it's fleshed out.
I also extracted the IomgrEventEngine's timer piece into a separate component, usable by both engines.