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net/http: fix rare Transport readLoop goroutine leak

There used to be a small window where if a server declared it would do
a keep-alive connection but then actually closed the connection before
the roundTrip goroutine scheduled after being sent a response from the
readLoop goroutine, then the readLoop goroutine would loop around and
block forever reading from a channel because the numExpectedResponses
accounting was done too late.

Fixes #10457

Change-Id: Icbae937ffe83c792c295b7f4fb929c6a24a4f759
Reviewed-on: https://go-review.googlesource.com/9169
Reviewed-by: Daniel Morsing <daniel.morsing@gmail.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Brad Fitzpatrick 2015-04-21 13:13:16 -07:00
parent 87054c4704
commit 58c1c011a6
2 changed files with 36 additions and 4 deletions

View File

@ -931,6 +931,10 @@ func (pc *persistConn) readLoop() {
}
}
pc.lk.Lock()
pc.numExpectedResponses--
pc.lk.Unlock()
// The connection might be going away when we put the
// idleConn below. When that happens, we close the response channel to signal
// to roundTrip that the connection is gone. roundTrip waits for
@ -1155,10 +1159,6 @@ WaitResponse:
}
}
pc.lk.Lock()
pc.numExpectedResponses--
pc.lk.Unlock()
if re.err != nil {
pc.t.setReqCanceler(req.Request, nil)
}

View File

@ -2092,6 +2092,38 @@ func TestTransportNoReuseAfterEarlyResponse(t *testing.T) {
}
}
// Tests that we don't leak Transport persistConn.readLoop goroutines
// when a server hangs up immediately after saying it would keep-alive.
func TestTransportIssue10457(t *testing.T) {
defer afterTest(t) // used to fail in goroutine leak check
ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
// Send a response with no body, keep-alive
// (implicit), and then lie and immediately close the
// connection. This forces the Transport's readLoop to
// immediately Peek an io.EOF and get to the point
// that used to hang.
conn, _, _ := w.(Hijacker).Hijack()
conn.Write([]byte("HTTP/1.1 200 OK\r\nFoo: Bar\r\nContent-Length: 0\r\n\r\n")) // keep-alive
conn.Close()
}))
defer ts.Close()
tr := &Transport{}
defer tr.CloseIdleConnections()
cl := &Client{Transport: tr}
res, err := cl.Get(ts.URL)
if err != nil {
t.Fatalf("Get: %v", err)
}
defer res.Body.Close()
// Just a sanity check that we at least get the response. The real
// test here is that the "defer afterTest" above doesn't find any
// leaked goroutines.
if got, want := res.Header.Get("Foo"), "Bar"; got != want {
t.Errorf("Foo header = %q; want %q", got, want)
}
}
type errorReader struct {
err error
}