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https://github.com/golang/go
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4c943abb95
Fixes for #49680, #49695, #45867, and #49370 all assumed that SetGCPercent(-1) doesn't block until the GC's mark phase is done, but it actually does. The cause of 3 of those 4 failures comes from the fact that at the beginning of the sweep phase, the GC does try to preempt every P once, and this may run concurrently with test code. In the fourth case, the issue was likely that only *one* of the debug_test.go tests was missing a call to SetGCPercent(-1). Just to be safe, leave a TODO there for now to remove the extraneous runtime.GC calls, but leave the calls in. Updates #49680, #49695, #45867, and #49370. Change-Id: Ibf4e64addfba18312526968bcf40f1f5d54eb3f1 Reviewed-on: https://go-review.googlesource.com/c/go/+/369815 Reviewed-by: Austin Clements <austin@google.com> Trust: Michael Knyszek <mknyszek@google.com> Run-TryBot: Michael Knyszek <mknyszek@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
68 lines
1.7 KiB
Go
68 lines
1.7 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test that SIGSETXID runs on signal stack, since it's likely to
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// overflow if it runs on the Go stack.
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package cgotest
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/*
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#include <sys/types.h>
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#include <unistd.h>
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*/
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import "C"
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import (
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"runtime"
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"runtime/debug"
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"sync/atomic"
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"testing"
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"cgotest/issue9400"
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)
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func test9400(t *testing.T) {
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// We synchronize through a shared variable, so we need two procs
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defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(2))
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// Start signaller
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atomic.StoreInt32(&issue9400.Baton, 0)
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go func() {
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// Wait for RewindAndSetgid
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for atomic.LoadInt32(&issue9400.Baton) == 0 {
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runtime.Gosched()
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}
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// Broadcast SIGSETXID
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runtime.LockOSThread()
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C.setgid(0)
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// Indicate that signalling is done
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atomic.StoreInt32(&issue9400.Baton, 0)
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}()
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// Grow the stack and put down a test pattern
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const pattern = 0x123456789abcdef
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var big [1024]uint64 // len must match assembly
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for i := range big {
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big[i] = pattern
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}
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// Disable GC for the duration of the test.
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// This avoids a potential GC deadlock when spinning in uninterruptable ASM below #49695.
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defer debug.SetGCPercent(debug.SetGCPercent(-1))
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// SetGCPercent waits until the mark phase is over, but the runtime
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// also preempts at the start of the sweep phase, so make sure that's
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// done too. See #49695.
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runtime.GC()
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// Temporarily rewind the stack and trigger SIGSETXID
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issue9400.RewindAndSetgid()
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// Check test pattern
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for i := range big {
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if big[i] != pattern {
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t.Fatalf("entry %d of test pattern is wrong; %#x != %#x", i, big[i], uint64(pattern))
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}
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}
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}
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