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- From 76a06b2804bcdba0fb2c19f834bdb511ce3cf344 Mon Sep 17 00:00:00 2001
- From: Willy Tarreau <w@1wt.eu>
- Date: Wed, 20 May 2015 10:39:04 +0200
- Subject: [PATCH 09/10] BUG/MEDIUM: peers: apply a random reconnection timeout
-
- Commit 9ff95bb ("BUG/MEDIUM: peers: correctly configure the client timeout")
- uncovered an old bug in the peers : upon disconnect, we reconnect immediately.
- This sometimes results in both ends to do the same thing in parallel causing
- a loop of connect/accept/close/close that can last several seconds. The risk
- of occurrence of the trouble increases with latency, and is emphasized by the
- fact that idle connections are now frequently recycled (after 5s of idle).
-
- In order to avoid this we must apply a random delay before reconnecting.
- Fortunately the mechanism already supports a reconnect delay, so here we
- compute the random timeout when killing a session. The delay is 50ms plus
- a random between 0 and 2 seconds. Ideally an exponential back-off would
- be preferred but it's preferable to keep the fix simple.
-
- This bug was reported by Marco Corte.
-
- This fix must be backported to 1.5 since the fix above was backported into
- 1.5.12.
- (cherry picked from commit b4e34da692d8a7f6837ad16b3389f5830dbc11d2)
- ---
- src/peers.c | 14 +++++++++++---
- 1 file changed, 11 insertions(+), 3 deletions(-)
-
- diff --git a/src/peers.c b/src/peers.c
- index b196d88..159f0a4 100644
- --- a/src/peers.c
- +++ b/src/peers.c
- @@ -1063,6 +1063,7 @@ static void peer_session_forceshutdown(struct session * session)
- {
- struct stream_interface *oldsi = NULL;
- struct appctx *appctx = NULL;
- + struct peer_session *ps;
- int i;
-
- for (i = 0; i <= 1; i++) {
- @@ -1079,6 +1080,14 @@ static void peer_session_forceshutdown(struct session * session)
- if (!appctx)
- return;
-
- + ps = (struct peer_session *)appctx->ctx.peers.ptr;
- + /* we're killing a connection, we must apply a random delay before
- + * retrying otherwise the other end will do the same and we can loop
- + * for a while.
- + */
- + if (ps)
- + ps->reconnect = tick_add(now_ms, MS_TO_TICKS(50 + random() % 2000));
- +
- /* call release to reinit resync states if needed */
- peer_session_release(oldsi);
- appctx->st0 = PEER_SESS_ST_END;
- @@ -1352,8 +1361,8 @@ static struct task *process_peer_sync(struct task * task)
- if (!ps->session) {
- /* no active session */
- if (ps->statuscode == 0 ||
- - ps->statuscode == PEER_SESS_SC_SUCCESSCODE ||
- ((ps->statuscode == PEER_SESS_SC_CONNECTCODE ||
- + ps->statuscode == PEER_SESS_SC_SUCCESSCODE ||
- ps->statuscode == PEER_SESS_SC_CONNECTEDCODE) &&
- tick_is_expired(ps->reconnect, now_ms))) {
- /* connection never tried
- @@ -1364,8 +1373,7 @@ static struct task *process_peer_sync(struct task * task)
- /* retry a connect */
- ps->session = peer_session_create(ps->peer, ps);
- }
- - else if (ps->statuscode == PEER_SESS_SC_CONNECTCODE ||
- - ps->statuscode == PEER_SESS_SC_CONNECTEDCODE) {
- + else if (!tick_is_expired(ps->reconnect, now_ms)) {
- /* If previous session failed during connection
- * but reconnection timer is not expired */
-
- --
- 2.0.5
-
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