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