tree e0cb6b836b21f861ab942ae2c1a52471a245e776
parent 2efe72e635474b402b4cd456f51c0bc5989931aa
author George Burgess IV <gbiv@google.com> 1592529027 -0700
committer George Burgess <gbiv@chromium.org> 1592617841 +0000

wrapper: fork() before exec()ing

This CL is a wild guess that tries to work around what appears to be an
incredibly rare Go runtime bug
(https://github.com/golang/go/issues/24484). As mentioned on the
chromium bug, apparently execve is taking a while... somehow, and
`pthread_create` fails with `EAGAIN` concurrently.

So the intent here is to `fork()` + `exec()`. `fork()` will
  a) dispose of the thread that's trying to `pthread_create`
  b) isolate the `exec` in its own process, so the parent's runtime can
     spin up as many threads as it likes in peace.

This slows down an 'ideal' kernel build (aka a build where ccache is a
100% hit rate, so the compiler wrapper's overheads are very pronounced)
by ~4% in my measurements.

BUG=chromium:1095528
TEST=sdk tryjob; CQ

Change-Id: I73e1b238738b74c85def4709c09610f586fb04e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2252552
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>