code review 6347061: net/http: fix Transport race(s) with high GOMAXPROCS

src/pkg/net/http/transport_test.go

 // Copyright 2011 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.
 
 // Tests for transport.go
 
 package http_test
 
 import (
         "bytes"
@@ skipping 839 matching lines @@
         }
         got, err := ioutil.ReadAll(res.Body)
         if err != nil {
                 t.Fatalf("Body ReadAll: %v", err)
         }
         if !strings.Contains(string(got), deniedMsg) {
                 t.Errorf("Known bug: response %q does not contain %q", got, deniedMsg)
         }
 }
 
+func TestTransportConcurrency(t *testing.T) {
+        const maxProcs = 16
+        const numReqs = 500
+        defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(maxProcs))
+        ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+                fmt.Fprintf(w, "%v", r.FormValue("echo"))
+        }))
+        defer ts.Close()
+        tr := &Transport{}
+        c := &Client{Transport: tr}
+        reqs := make(chan string)
+        defer close(reqs)
+
+        var wg sync.WaitGroup
+        wg.Add(numReqs)
+        for i := 0; i < maxProcs*2; i++ {
+                go func() {
+                        for req := range reqs {
+                                res, err := c.Get(ts.URL + "/?echo=" + req)
+                                if err != nil {
+                                        t.Errorf("error on req %s: %v", req, err)
+                                        wg.Done()
+                                        continue
+                                }
+                                all, err := ioutil.ReadAll(res.Body)
+                                if err != nil {
+                                        t.Errorf("read error on req %s: %v", req, err)
+                                        wg.Done()
+                                        continue
+                                }
+                                if string(all) != req {
+                                        t.Errorf("body of req %s = %q; want %q", req, all, req)
+                                }
+                                wg.Done()
+                                res.Body.Close()
+                        }
+                }()
+        }
+        for i := 0; i < numReqs; i++ {
+                reqs <- fmt.Sprintf("request-%d", i)
+        }
+        wg.Wait()
+}
+
 type fooProto struct{}
 
 func (fooProto) RoundTrip(req *Request) (*Response, error) {
         res := &Response{
                 Status:     "200 OK",
                 StatusCode: 200,
                 Header:     make(Header),
                 Body:       ioutil.NopCloser(strings.NewReader("You wanted " + req.URL.String())),
         }
         return res, nil
@@ skipping 75 matching lines @@
         0xff, 0xff, 0x00, 0x00, 0x00, 0xff, 0xff, 0x00,
         0x17, 0x00, 0xe8, 0xff, 0x42, 0x12, 0x46, 0x16,
         0x06, 0x00, 0x00, 0x00, 0xff, 0xff, 0x01, 0x08,
         0x00, 0xf7, 0xff, 0x3d, 0xb1, 0x20, 0x85, 0xfa,
         0x00, 0x00, 0x00, 0x42, 0x12, 0x46, 0x16, 0x06,
         0x00, 0x00, 0x00, 0xff, 0xff, 0x01, 0x08, 0x00,
         0xf7, 0xff, 0x3d, 0xb1, 0x20, 0x85, 0xfa, 0x00,
         0x00, 0x00, 0x3d, 0xb1, 0x20, 0x85, 0xfa, 0x00,
         0x00, 0x00,
 }