net/http: fix client goroutine leak with persistent connections

Thanks to Sascha Matzke & Florian Weimer for diagnosing.

R=golang-dev, adg, bradfitz, kevlar
CC=golang-dev
http://codereview.appspot.com/5656046

1 files changed, 15 insertions, 6 deletions

diff --git a/src/pkg/net/http/transport.go b/src/pkg/net/http/transport.go
index 510e55b05..3e48abafb 100644
--- a/src/pkg/net/http/transport.go
+++ b/src/pkg/net/http/transport.go
@@ -235,15 +235,19 @@ func (cm *connectMethod) proxyAuth() string {
 	return ""
 }
 
-func (t *Transport) putIdleConn(pconn *persistConn) {
+// putIdleConn adds pconn to the list of idle persistent connections awaiting
+// a new request.
+// If pconn is no longer needed or not in a good state, putIdleConn
+// returns false.
+func (t *Transport) putIdleConn(pconn *persistConn) bool {
 	t.lk.Lock()
 	defer t.lk.Unlock()
 	if t.DisableKeepAlives || t.MaxIdleConnsPerHost < 0 {
 		pconn.close()
-		return
+		return false
 	}
 	if pconn.isBroken() {
-		return
+		return false
 	}
 	key := pconn.cacheKey
 	max := t.MaxIdleConnsPerHost
@@ -252,9 +256,10 @@ func (t *Transport) putIdleConn(pconn *persistConn) {
 	}
 	if len(t.idleConn[key]) >= max {
 		pconn.close()
-		return
+		return false
 	}
 	t.idleConn[key] = append(t.idleConn[key], pconn)
+	return true
 }
 
 func (t *Transport) getIdleConn(cm *connectMethod) (pconn *persistConn) {
@@ -565,7 +570,9 @@ func (pc *persistConn) readLoop() {
 				lastbody = resp.Body
 				waitForBodyRead = make(chan bool)
 				resp.Body.(*bodyEOFSignal).fn = func() {
-					pc.t.putIdleConn(pc)
+					if !pc.t.putIdleConn(pc) {
+						alive = false
+					}
 					waitForBodyRead <- true
 				}
 			} else {
@@ -578,7 +585,9 @@ func (pc *persistConn) readLoop() {
 				// read it (even though it'll just be 0, EOF).
 				lastbody = nil
 
-				pc.t.putIdleConn(pc)
+				if !pc.t.putIdleConn(pc) {
+					alive = false
+				}
 			}
 		}