code review 7369056: net/http: fix a bunch of test leaks

src/pkg/net/http/z_last_test.go

+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package http_test
+
+import (
+        "net/http"
+        "runtime"
+        "strings"
+        "testing"
+        "time"
+)
+
+// Verify the other tests didn't leave any goroutines running.
+// This is in a file named z_last_test.go so it sorts at the end.

[adg, 2013/02/27 00:31:50]

I'm not sure the go tool makes and guarantees about this...

[bradfitz, 2013/02/27 01:12:54]

well, if I ever see it not be at the end, we'll adapt somehow, or get it
guaranteed.

+func TestGoroutinesRunning(t *testing.T) {
+        n := runtime.NumGoroutine()
+        t.Logf("num goroutines = %d", n)
+        if n > 20 {
+                // Currently 14 on Linux (blocked in epoll_wait,
+                // waiting for on fds that are closed?), but give some
+                // slop for now.
+                buf := make([]byte, 1<<20)
+                buf = buf[:runtime.Stack(buf, true)]

[adg, 2013/02/27 00:31:50]

haha weird

+                t.Errorf("Too many goroutines:\n%s", buf)
+        }
+}
+
+func checkLeakedTransports(t *testing.T) {
+        http.DefaultTransport.(*http.Transport).CloseIdleConnections()
+        if testing.Short() {
+                return
+        }
+        buf := make([]byte, 1<<20)
+        var stacks string
+        var bad string
+        badSubstring := map[string]string{
+                ").readLoop(":                                  "a Transport",

[adg, 2013/02/27 00:31:50]

sorry, did I say line 25 was weird? THIS is weird :-)

+                ").writeLoop(":                                 "a Transport",
+                "created by net/http/httptest.(*Server).Start": "an httptest.Server",
+                "timeoutHandler":                               "a TimeoutHandler",
+        }
+        for i := 0; i < 4; i++ {
+                bad = ""
+                stacks = string(buf[:runtime.Stack(buf, true)])
+                for substr, what := range badSubstring {
+                        if strings.Contains(stacks, substr) {
+                                bad = what
+                        }
+                }
+                if bad == "" {
+                        return
+                }
+                // Bad stuff found, but goroutines might just still be
+                // shutting down, so give it some time.
+                time.Sleep(250 * time.Millisecond)
+        }
+        t.Errorf("Test appears to have leaked %s:\n%s", bad, stacks)
+}