device: test that we do not leak goroutines

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>

diff --git a/device/device_test.go b/device/device_test.go
index d1af22561717f70bb392fb37487c0fcdf0241d46..9290ff04352686a496a02023d43d942b372a8c42 100644 (file)
--- a/device/device_test.go
+++ b/device/device_test.go
@@ -12,6 +12,8 @@ import (
        "io"
        "io/ioutil"
        "net"
+       "runtime"
+       "runtime/pprof"
        "sync"
        "sync/atomic"
        "testing"
@@ -163,6 +165,7 @@ NextAttempt:
                                // If there's something permanent wrong,
                                // we'll see that when we run out of attempts.
                                tb.Logf("failed to configure device %d: %v", i, err)
+                               p.dev.Close()
                                continue NextAttempt
                        }
                        // The device might still not be up, e.g. due to an error
@@ -170,6 +173,7 @@ NextAttempt:
                        // Assume it's due to a transient error (port in use), and retry.
                        if !p.dev.isUp.Get() {
                                tb.Logf("device %d did not come up, trying again", i)
+                               p.dev.Close()
                                continue NextAttempt
                        }
                        // The device is up. Close it when the test completes.
@@ -183,6 +187,7 @@ NextAttempt:
 }
 
 func TestTwoDevicePing(t *testing.T) {
+       goroutineLeakCheck(t)
        pair := genTestPair(t)
        t.Run("ping 1.0.0.1", func(t *testing.T) {
                pair.Send(t, Ping, nil)
@@ -352,3 +357,29 @@ func BenchmarkUAPIGet(b *testing.B) {
                pair[0].dev.IpcGetOperation(ioutil.Discard)
        }
 }
+
+func goroutineLeakCheck(t *testing.T) {
+       goroutines := func() (int, []byte) {
+               p := pprof.Lookup("goroutine")
+               b := new(bytes.Buffer)
+               p.WriteTo(b, 1)
+               return p.Count(), b.Bytes()
+       }
+
+       startGoroutines, startStacks := goroutines()
+       t.Cleanup(func() {
+               if t.Failed() {
+                       return
+               }
+               // Give goroutines time to exit, if they need it.
+               for i := 0; i < 1000 && startGoroutines < runtime.NumGoroutine(); i++ {
+                       time.Sleep(10 * time.Millisecond)
+               }
+               if got := runtime.NumGoroutine(); startGoroutines < got {
+                       _, endStacks := goroutines()
+                       t.Logf("starting stacks:\n%s\n", startStacks)
+                       t.Logf("ending stacks:\n%s\n", endStacks)
+                       t.Fatalf("expected %d goroutines, got %d, leak?", startGoroutines, got)
+               }
+       })
+}