app/vmstorage: addd missing -inmemoryDataFlushInterval command-line flag

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3337

README.md

@@ -1490,6 +1490,8 @@ Below is the output for `/path/to/vmstorage -help`:
      Address to listen for http connections. See also -httpListenAddr.useProxyProtocol (default ":8482")
   -httpListenAddr.useProxyProtocol
      Whether to use proxy protocol for connections accepted at -httpListenAddr . See https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt . With enabled proxy protocol http server cannot serve regular /metrics endpoint. Use -pushmetrics.url for metrics pushing
+  -inmemoryDataFlushInterval duration
+     The interval for guaranteed saving of in-memory data to disk. The saved data survives unclean shutdowns such as OOM crash, hardware reset, SIGKILL, etc. Bigger intervals may help increase the lifetime of flash storage with limited write cycles (e.g. Raspberry PI). Smaller intervals increase disk IO load. Minimum supported value is 1s (default 5s)
   -insert.maxQueueDuration duration
      The maximum duration to wait in the queue when -maxConcurrentInserts concurrent insert requests are executed (default 1m0s)
   -internStringCacheExpireDuration duration

app/vmstorage/main.go

@@ -52,6 +52,10 @@ var (
 		"If set to 2h, then the indexdb rotation is performed at 4am EET time (the timezone with +2h offset)")
 	minScrapeInterval = flag.Duration("dedup.minScrapeInterval", 0, "Leave only the last sample in every time series per each discrete interval "+
 		"equal to -dedup.minScrapeInterval > 0. See https://docs.victoriametrics.com/#deduplication for details")
+	inmemoryDataFlushInterval = flag.Duration("inmemoryDataFlushInterval", 5*time.Second, "The interval for guaranteed saving of in-memory data to disk. "+
+		"The saved data survives unclean shutdowns such as OOM crash, hardware reset, SIGKILL, etc. "+
+		"Bigger intervals may help increase the lifetime of flash storage with limited write cycles (e.g. Raspberry PI). "+
+		"Smaller intervals increase disk IO load. Minimum supported value is 1s")
 
 	logNewSeries = flag.Bool("logNewSeries", false, "Whether to log new series. This option is for debug purposes only. It can lead to performance issues "+
 		"when big number of new series are ingested into VictoriaMetrics")
@@ -84,6 +88,7 @@ func main() {
 	pushmetrics.Init()
 
 	storage.SetDedupInterval(*minScrapeInterval)
+	storage.SetDataFlushInterval(*inmemoryDataFlushInterval)
 	storage.SetLogNewSeries(*logNewSeries)
 	storage.SetFinalMergeDelay(*finalMergeDelay)
 	storage.SetMergeWorkersCount(*smallMergeConcurrency)

docs/CHANGELOG.md

@@ -30,6 +30,8 @@ The sandbox cluster installation is running under the constant load generated by
 
 * FEATURE: [vmauth](https://docs.victoriametrics.com/vmauth.html): add ability to proxy incoming requests to different backends based on the requested host via `src_hosts` option at `url_map`. See [these docs](https://docs.victoriametrics.com/vmauth.html#generic-http-proxy-for-different-backends).
 
+* BUGFIX: `vmstorage`: added missing `-inmemoryDataFlushInterval` command-line flag, which was missing in [VictoriaMetrics cluster](https://docs.victoriametrics.com/Cluster-VictoriaMetrics.html) after implementing [this feature](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3337) in [v1.85.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.85.0).
+
 * BUGFIX: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): properly handle queries, which wrap [rollup functions](https://docs.victoriametrics.com/MetricsQL.html#rollup-functions) with multiple arguments without explicitly specified lookbehind window in square brackets into [aggregate functions](https://docs.victoriametrics.com/MetricsQL.html#aggregate-functions). For example, `sum(quantile_over_time(0.5, process_resident_memory_bytes))` was resulting to `expecting at least 2 args to ...; got 1 args' error. Thanks to @atykhyy for [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5414).
 
 ## [v1.96.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.96.0)

docs/Cluster-VictoriaMetrics.md

@@ -1501,6 +1501,8 @@ Below is the output for `/path/to/vmstorage -help`:
      Address to listen for http connections. See also -httpListenAddr.useProxyProtocol (default ":8482")
   -httpListenAddr.useProxyProtocol
      Whether to use proxy protocol for connections accepted at -httpListenAddr . See https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt . With enabled proxy protocol http server cannot serve regular /metrics endpoint. Use -pushmetrics.url for metrics pushing
+  -inmemoryDataFlushInterval duration
+     The interval for guaranteed saving of in-memory data to disk. The saved data survives unclean shutdowns such as OOM crash, hardware reset, SIGKILL, etc. Bigger intervals may help increase the lifetime of flash storage with limited write cycles (e.g. Raspberry PI). Smaller intervals increase disk IO load. Minimum supported value is 1s (default 5s)
   -insert.maxQueueDuration duration
      The maximum duration to wait in the queue when -maxConcurrentInserts concurrent insert requests are executed (default 1m0s)
   -internStringCacheExpireDuration duration