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sync: remove TestWaitGroupMisuse2 and TestWaitGroupMisuse3
These tests are inherently nondeterministic: They exercise a racy code path for up to one million iterations, and require that an error occur at least once. TestWaitGroupMisuse2 in particular is an ongoing source of trybot flakiness. Fixes #38163. Change-Id: Ibbbda2c998c915333487ad262d3df6829de01c2b Reviewed-on: https://go-review.googlesource.com/c/go/+/340249 Trust: Damien Neil <dneil@google.com> Trust: Dmitri Shuralyov <dmitshur@golang.org> Run-TryBot: Damien Neil <dneil@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
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@ -5,8 +5,6 @@
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package sync_test
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import (
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"internal/race"
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"runtime"
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. "sync"
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"sync/atomic"
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"testing"
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@ -48,12 +46,6 @@ func TestWaitGroup(t *testing.T) {
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}
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}
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func knownRacy(t *testing.T) {
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if race.Enabled {
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t.Skip("skipping known-racy test under the race detector")
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}
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}
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func TestWaitGroupMisuse(t *testing.T) {
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defer func() {
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err := recover()
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@ -68,124 +60,6 @@ func TestWaitGroupMisuse(t *testing.T) {
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t.Fatal("Should panic")
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}
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// pollUntilEqual blocks until v, loaded atomically, is
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// equal to the target.
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func pollUntilEqual(v *uint32, target uint32) {
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for {
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for i := 0; i < 1e3; i++ {
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if atomic.LoadUint32(v) == target {
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return
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}
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}
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// yield to avoid deadlock with the garbage collector
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// see issue #20072
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runtime.Gosched()
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}
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}
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func TestWaitGroupMisuse2(t *testing.T) {
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knownRacy(t)
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if runtime.NumCPU() <= 4 {
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t.Skip("NumCPU<=4, skipping: this test requires parallelism")
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}
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defer func() {
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err := recover()
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if err != "sync: negative WaitGroup counter" &&
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err != "sync: WaitGroup misuse: Add called concurrently with Wait" &&
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err != "sync: WaitGroup is reused before previous Wait has returned" {
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t.Fatalf("Unexpected panic: %#v", err)
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}
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}()
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defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
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done := make(chan interface{}, 2)
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// The detection is opportunistic, so we want it to panic
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// at least in one run out of a million.
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for i := 0; i < 1e6; i++ {
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var wg WaitGroup
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var here uint32
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wg.Add(1)
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go func() {
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defer func() {
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done <- recover()
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}()
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atomic.AddUint32(&here, 1)
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pollUntilEqual(&here, 3)
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wg.Wait()
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}()
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go func() {
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defer func() {
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done <- recover()
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}()
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atomic.AddUint32(&here, 1)
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pollUntilEqual(&here, 3)
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wg.Add(1) // This is the bad guy.
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wg.Done()
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}()
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atomic.AddUint32(&here, 1)
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pollUntilEqual(&here, 3)
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wg.Done()
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for j := 0; j < 2; j++ {
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if err := <-done; err != nil {
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panic(err)
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}
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}
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}
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t.Fatal("Should panic")
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}
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func TestWaitGroupMisuse3(t *testing.T) {
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knownRacy(t)
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if runtime.NumCPU() <= 1 {
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t.Skip("NumCPU==1, skipping: this test requires parallelism")
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}
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defer func() {
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err := recover()
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if err != "sync: negative WaitGroup counter" &&
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err != "sync: WaitGroup misuse: Add called concurrently with Wait" &&
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err != "sync: WaitGroup is reused before previous Wait has returned" {
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t.Fatalf("Unexpected panic: %#v", err)
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}
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}()
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defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
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done := make(chan interface{}, 3)
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// The detection is opportunistically, so we want it to panic
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// at least in one run out of a million.
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for i := 0; i < 1e6; i++ {
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var wg WaitGroup
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wg.Add(1)
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go func() {
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defer func() {
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done <- recover()
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}()
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wg.Done()
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}()
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go func() {
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defer func() {
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done <- recover()
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}()
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wg.Wait()
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// Start reusing the wg before waiting for the Wait below to return.
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wg.Add(1)
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go func() {
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wg.Done()
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}()
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wg.Wait()
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}()
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go func() {
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defer func() {
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done <- recover()
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}()
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wg.Wait()
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}()
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for j := 0; j < 3; j++ {
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if err := <-done; err != nil {
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panic(err)
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}
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}
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}
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t.Fatal("Should panic")
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}
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func TestWaitGroupRace(t *testing.T) {
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// Run this test for about 1ms.
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for i := 0; i < 1000; i++ {
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