runtime: more deflaking of TestCgoCheckBytes

Fixes #14519.

Change-Id: I8f78f67a463e6467e09df90446f7ebd28789d6c9
Reviewed-on: https://go-review.googlesource.com/19933
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index 635e271d5d3fc4f0fbe294b31ce501b0a345b8d3..00686ee7559a8362292b85d5ff457362c090c559 100644 (file)
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -7,6 +7,7 @@
 package runtime_test
 
 import (
+       "fmt"
        "internal/testenv"
        "os/exec"
        "runtime"
@@ -161,22 +162,35 @@ func TestCgoCheckBytes(t *testing.T) {
                t.Fatal(err)
        }
 
-       cmd := testEnv(exec.Command(exe, "CgoCheckBytes"))
-       cmd.Env = append(cmd.Env, "GODEBUG=cgocheck=0")
+       // Try it 10 times to avoid flakiness.
+       const tries = 10
+       var tot1, tot2 time.Duration
+       for i := 0; i < tries; i++ {
+               cmd := testEnv(exec.Command(exe, "CgoCheckBytes"))
+               cmd.Env = append(cmd.Env, "GODEBUG=cgocheck=0", fmt.Sprintf("GO_CGOCHECKBYTES_TRY=%d", i))
 
-       start := time.Now()
-       cmd.Run()
-       d1 := time.Since(start)
+               start := time.Now()
+               cmd.Run()
+               d1 := time.Since(start)
 
-       cmd = testEnv(exec.Command(exe, "CgoCheckBytes"))
+               cmd = testEnv(exec.Command(exe, "CgoCheckBytes"))
+               cmd.Env = append(cmd.Env, fmt.Sprintf("GO_CGOCHECKBYTES_TRY=%d", i))
 
-       start = time.Now()
-       cmd.Run()
-       d2 := time.Since(start)
+               start = time.Now()
+               cmd.Run()
+               d2 := time.Since(start)
 
-       if d1*20 < d2 {
-               t.Errorf("cgo check too slow: got %v, expected at most %v", d1, d2*10)
+               if d1*20 > d2 {
+                       // The slow version (d2) was less than 20 times
+                       // slower than the fast version (d1), so OK.
+                       return
+               }
+
+               tot1 += d1
+               tot2 += d2
        }
+
+       t.Errorf("cgo check too slow: got %v, expected at most %v", tot2/tries, (tot1/tries)*20)
 }
 
 func TestCgoPanicDeadlock(t *testing.T) {

diff --git a/src/runtime/testdata/testprogcgo/cgo.go b/src/runtime/testdata/testprogcgo/cgo.go
index 5d2550dbb0343542bac5f3ee5ee64edd41d353c3..7a2e013d43b058e436aaa560692d3290192d766a 100644 (file)
--- a/src/runtime/testdata/testprogcgo/cgo.go
+++ b/src/runtime/testdata/testprogcgo/cgo.go
@@ -11,7 +11,9 @@ void foo2(void* p) {}
 import "C"
 import (
        "fmt"
+       "os"
        "runtime"
+       "strconv"
        "time"
        "unsafe"
 )
@@ -83,8 +85,16 @@ func CgoTraceback() {
 }
 
 func CgoCheckBytes() {
-       b := make([]byte, 1e6)
-       for i := 0; i < 1e3; i++ {
+       try, _ := strconv.Atoi(os.Getenv("GO_CGOCHECKBYTES_TRY"))
+       if try <= 0 {
+               try = 1
+       }
+       b := make([]byte, 1e6*try)
+       start := time.Now()
+       for i := 0; i < 1e3*try; i++ {
                C.foo2(unsafe.Pointer(&b[0]))
+               if time.Since(start) > time.Second {
+                       break
+               }
        }
 }