internal/trace: don't report regions on system goroutines

If a goroutine is started within a user region, internal/trace assigns
the child goroutine a nameless region for its entire lifetime which is
assosciated the same task as the parent's region.

This is not strictly necessary: a child goroutine is not necessarily
related to the task unless it performs some task operation (in which
case it will be associated with the task through the standard means).

However, it can be quite handy to see child goroutines within a region,
which may be child worker goroutines that you simply didn't perform task
operations on.

If the first GC occurs during a region, the GC worker goroutines will
also inherit a child region. We know for sure that these aren't related
to the task, so filter them out from the region list.

Note that we can't exclude system goroutines from setting activeRegions
in EvGoCreate handling, because we don't know the goroutine start
function name until the first EvGoStart.

Fixes #53784.

Change-Id: Ic83d84e23858a8400a76d1ae2f1418ef49951178
Reviewed-on: https://go-review.googlesource.com/c/go/+/416858
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

0 files changed, 0 insertions, 0 deletions