Hi Milan, hi Janusz,
thanks to your respective traces, I may have come up with a possible
scenario explaining the CLOSE_WAIT you're facing. Could you please
try the attached patch ?
Thanks,
Willy
>From fc527303f1391849ae5880b304486e328010b5ff Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w...@1wt.eu>
Date: Wed, 13 Jun 2018 14:24:56 +0200
Subject: BUG/MEDIUM: h2: make sure the last stream closes the connection
after a timeout
If a timeout strikes on the connection side with some active streams,
there is a corner case which can sometimes cause the following sequence
to happen :
- There are active streams but there are data in the mux buffer
(eg: a client suddenly disconnected during a download with pending
requests). The timeout is active.
- The timeout strikes, h2_timeout_task() is called, kills the task and
doesn't close the connection since there are streams left ; The
connection is marked in H2_CS_ERROR ;
- the streams are woken up and closed ;
- when the last stream closes, calling h2_detach(), it sees the
tree list is empty, but there is no condition allowing the
connection to be closed (mbuf->o > 0), thus it does nothing ;
- since the task is dead, there's no more hope to clear this
situation later
For now we can take care of this by adding a test for the presence of
H2_CS_ERROR and !task, implying the timeout task triggered already
and will not be able to handle this again.
Over the long term it seems like a more reliable test on should be
made, so that it is possible to know whether or not someone is still
able to close this connection.
A big thanks to Janusz Dziemidowicz and Milan Petruzelka for providing
many details helping in figuring this bug.
---
src/mux_h2.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/src/mux_h2.c b/src/mux_h2.c
index 57b1722..bc33ce2 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -2469,6 +2469,7 @@ static void h2_detach(struct conn_stream *cs)
*/
if (eb_is_empty(&h2c->streams_by_id) && /* don't close if streams
exist */
((h2c->conn->flags & CO_FL_ERROR) || /* errors close immediately
*/
+ (h2c->st0 >= H2_CS_ERROR && !h2c->task) || /* a timeout stroke
earlier */
(h2c->flags & H2_CF_GOAWAY_FAILED) ||
(!h2c->mbuf->o && /* mux buffer empty, also process clean events
below */
(conn_xprt_read0_pending(h2c->conn) ||
--
1.7.12.1
