runtime/pprof: retry vmmap invocation if it failed due to a reported temporary resour...

As per #62352 the invocation of vmmap may fail (very rarely) due to
a temporary lack of resources on the test runner machine. This PR
allows for retrying the invocation a fixed number of times before
giving up. This is because we suspect the failure is due to
sensible to retry.

Fixes: #62352
Change-Id: I51aa66b949753d8127cc307181b6ef32e91d5b05
Reviewed-on: https://go-review.googlesource.com/c/go/+/545935
Auto-Submit: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>

diff --git a/src/runtime/pprof/vminfo_darwin_test.go b/src/runtime/pprof/vminfo_darwin_test.go
index 1a3b67a0bf1e3dc3475f093addf4381cc7cd34c8..8749a13390245d759e85952dec71e02d0cd00e70 100644 (file)
--- a/src/runtime/pprof/vminfo_darwin_test.go
+++ b/src/runtime/pprof/vminfo_darwin_test.go
@@ -34,7 +34,10 @@ func TestVMInfo(t *testing.T) {
                // the go toolchain itself.
                first = false
        })
-       lo, hi := useVMMap(t)
+       lo, hi, err := useVMMapWithRetry(t)
+       if err != nil {
+               t.Fatal(err)
+       }
        if got, want := begin, lo; got != want {
                t.Errorf("got %x, want %x", got, want)
        }
@@ -53,7 +56,21 @@ func TestVMInfo(t *testing.T) {
        }
 }
 
-func useVMMap(t *testing.T) (hi, lo uint64) {
+func useVMMapWithRetry(t *testing.T) (hi, lo uint64, err error) {
+       var retryable bool
+       for {
+               hi, lo, retryable, err = useVMMap(t)
+               if err == nil {
+                       return hi, lo, nil
+               }
+               if !retryable {
+                       return 0, 0, err
+               }
+               t.Logf("retrying vmmap after error: %v", err)
+       }
+}
+
+func useVMMap(t *testing.T) (hi, lo uint64, retryable bool, err error) {
        pid := strconv.Itoa(os.Getpid())
        testenv.MustHaveExecPath(t, "vmmap")
        cmd := testenv.Command(t, "vmmap", pid)
@@ -63,20 +80,24 @@ func useVMMap(t *testing.T) (hi, lo uint64) {
                if ee, ok := cmdErr.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
                        t.Logf("%v: %v\n%s", cmd, cmdErr, ee.Stderr)
                }
+               retryable = bytes.Contains(out, []byte("resource shortage"))
                t.Logf("%v: %v", cmd, cmdErr)
+               if retryable {
+                       return 0, 0, true, cmdErr
+               }
        }
        // Always parse the output of vmmap since it may return an error
        // code even if it successfully reports the text segment information
        // required for this test.
-       hi, lo, err := parseVmmap(out)
+       hi, lo, err = parseVmmap(out)
        if err != nil {
                if cmdErr != nil {
-                       t.Fatalf("failed to parse vmmap output, vmmap reported an error: %v", err)
+                       return 0, 0, false, fmt.Errorf("failed to parse vmmap output, vmmap reported an error: %v", err)
                }
                t.Logf("vmmap output: %s", out)
-               t.Fatalf("failed to parse vmmap output, vmmap did not report an error: %v", err)
+               return 0, 0, false, fmt.Errorf("failed to parse vmmap output, vmmap did not report an error: %v", err)
        }
-       return hi, lo
+       return hi, lo, false, nil
 }
 
 // parseVmmap parses the output of vmmap and calls addMapping for the first r-x TEXT segment in the output.