From 42512927088c530acf356aaedaa557e89c790553 Mon Sep 17 00:00:00 2001
From: hagen1778 <roman@victoriametrics.com>
Date: Tue, 23 Apr 2024 14:49:45 +0200
Subject: [PATCH] app/vmagent: mention corner case with dangling queues and
identical URLs
See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6140
We don't cover this corner case as it has low chance for reproduction.
Precisely, the requirements are following:
1. vmagent need to be configured with multiple identical `remoteWrite.url` flags;
2. At least one of the persistent queues need to be non-empty, which already
signalizes about issues with setup;
3. vmagent need to be restarted with removing of one of `remoteWrite.url` flags.
We do not document this case in vmagent.md as it seems to be a rare corner case
and its explanation will require too much of explanation and confuse users.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
---
app/vmagent/remotewrite/remotewrite.go | 3 +++
1 file changed, 3 insertions(+)
diff --git a/app/vmagent/remotewrite/remotewrite.go b/app/vmagent/remotewrite/remotewrite.go
index 7cd8415cb1..93e41b50d4 100644
--- a/app/vmagent/remotewrite/remotewrite.go
+++ b/app/vmagent/remotewrite/remotewrite.go
@@ -259,6 +259,9 @@ func dropDanglingQueues() {
// This is required for the case when the number of queues has been changed or URL have been changed.
// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4014
//
+ // In case if there were many persistent queues with identical *remoteWriteURLs
+ // the queue with the last index will be dropped.
+ // See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6140
existingQueues := make(map[string]struct{}, len(rwctxsDefault))
for _, rwctx := range rwctxsDefault {
existingQueues[rwctx.fq.Dirname()] = struct{}{}