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| author | Michael Anthony Knyszek <mknyszek@google.com> | 2021-11-01 19:39:18 +0000 |
|---|---|---|
| committer | Michael Knyszek <mknyszek@google.com> | 2021-11-02 13:43:24 +0000 |
| commit | 4d7bf41bebc7ad4f71150b8b57fca12aff6da144 (patch) | |
| tree | ce66cab45ab3a0a4a0232d990bc7f56a544f70c8 /src/syscall | |
| parent | 088bb4bf4ad851a7f9a0d409e2f64c483cb7121a (diff) | |
| download | go-4d7bf41bebc7ad4f71150b8b57fca12aff6da144.tar.xz | |
syscall: remove GOMAXPROCS change in TestExecHelper
TestExec and TestExecHelper check for a workaround of a particular OS
bug on darwin that's triggered more often via asynchronous preemption.
As part of this, the test sets up 100 CPU-bound goroutines, and sets
GOMAXPROCS to 50, sleeping for a little bit before calling Exec. Thus
far, this is fine because the scheduler runs the Execing goroutine in a
timely manner. However, CL 309869 will reduce the minimum heap size,
causing a GC to happen during the test.
On a 16 CPU machine, with GOMAXPROCS at 50, and 100 CPU-bound
goroutines, both the OS scheduler and the Go scheduler are severly
oversaturated. As a result, the test often (not always, but often) runs
out for the full lifetime of those 100 goroutines, which run for about 1
second.
The minimum heap size reduction is not necessary to trigger this; an
additional call to runtime.GC in the helper is also sufficient to
trigger this delay.
The delay on its own isn't great, since it adds a whole second to
all.bash on its own. However, it also seems correlated with other
subprocess tests in the syscall package, namely TestPassFD and
TestFcntlFlock. These tests fail in a fairly superficial way: the file
descriptor for the temporary directories they make gets clobbered, is
closed, or becomes stale.
Change-Id: I213dd5e38967d19a8b317e6d4c5024b57f9e3fed
Reviewed-on: https://go-review.googlesource.com/c/go/+/360574
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Diffstat (limited to 'src/syscall')
| -rw-r--r-- | src/syscall/exec_unix_test.go | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/src/syscall/exec_unix_test.go b/src/syscall/exec_unix_test.go index 55f5f7025a..b7ae77552b 100644 --- a/src/syscall/exec_unix_test.go +++ b/src/syscall/exec_unix_test.go @@ -13,7 +13,6 @@ import ( "os" "os/exec" "os/signal" - "runtime" "syscall" "testing" "time" @@ -327,7 +326,6 @@ func TestExecHelper(t *testing.T) { // We don't have to worry about restoring these values. // We are in a child process that only runs this test, // and we are going to call syscall.Exec anyhow. - runtime.GOMAXPROCS(50) os.Setenv("GO_WANT_HELPER_PROCESS", "3") stop := time.Now().Add(time.Second) |