app/vmagent: properly perform graceful shutdown, which was broken in the commit 1d1ba889fe

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1065

app/vmagent/remotewrite/remotewrite.go

@@ -227,6 +227,7 @@ func (rwctx *remoteWriteCtx) MustStop() {
 	}
 	rwctx.idx = 0
 	rwctx.pss = nil
+	rwctx.fq.UnblockAllReaders()
 	rwctx.c.MustStop()
 	rwctx.c = nil
 	rwctx.fq.MustClose()

docs/CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * FEATURE: vmagent: add `scrape_align_interval` config option, which can be used for aligning scrapes to the beginning of the configured interval. See [these docs](https://victoriametrics.github.io/vmagent.html#troubleshooting) for details.
 
+* BUGFIX: vmagent: properly perform graceful shutdown on `SIGINT` and `SIGTERM` signals. The graceful shutdown has been broken in `v1.54.0`. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1065
 * BUGFIX: reduce the probability of `duplicate time series` errors when querying Kubernetes metrics.
 
 

lib/persistentqueue/fastqueue.go

@@ -52,16 +52,24 @@ func MustOpenFastQueue(path, name string, maxInmemoryBlocks, maxPendingBytes int
 	return fq
 }
 
-// MustClose unblocks all the readers.
+// UnblockAllReaders unblocks all the readers.
-//
+func (fq *FastQueue) UnblockAllReaders() {
-// It is expected no new writers during and after the call.
-func (fq *FastQueue) MustClose() {
 	fq.mu.Lock()
 	defer fq.mu.Unlock()
 
 	// Unblock blocked readers
 	fq.mustStop = true
 	fq.cond.Broadcast()
+}
+
+// MustClose unblocks all the readers.
+//
+// It is expected no new writers during and after the call.
+func (fq *FastQueue) MustClose() {
+	fq.UnblockAllReaders()
+
+	fq.mu.Lock()
+	defer fq.mu.Unlock()
 
 	// flush blocks from fq.ch to fq.pq, so they can be persisted
 	fq.flushInmemoryBlocksToFileLocked()