lib/cgroup: use the default GOGC=100 for the most of VictoriaMetrics components

Historically some of VictoriaMetrics components were optimized for the low rate of memory allocations.
These are: vmagent, single-node VictoriaMetrics and vmstorage. These components benefit from the low
GOGC value, since this allow reducing their memory usage in steady state on typical workloads.

Other VictoriaMetrics components aren't optimized for the reduced rate of memory allocations.
This results in the increased CPU usage spent on garbage collection (GC) in these components,
since it must be triggered at higher rate. See https://tip.golang.org/doc/gc-guide#GOGC for details.

These components do not use too much memory, so it is OK increasing the GOGC for these components
from 30 to 100 - this won't affect the most users.

Keep GOGC to 30 only for vmagent, single-node VictoriaMetrics and vmstorage components.
See 077193d87c and 54b9e1d3cb .

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/7902

app/vmagent/main.go

@@ -30,6 +30,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/auth"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/buildinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envflag"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
@@ -97,6 +98,15 @@ var (
 )
 
 func main() {
+	// vmagent is optimized for reduced memory allocations,
+	// so it can run with the reduced GOGC in order to reduce the used memory,
+	// while keeping CPU usage spent in GC at low levels.
+	//
+	// Some workloads may need increased GOGC values. Then such values can be set via GOGC environment variable.
+	// It is recommended increasing GOGC if go_memstats_gc_cpu_fraction metric exposed at /metrics page
+	// exceeds 0.05 for extended periods of time.
+	cgroup.SetGOGC(30)
+
 	// Write flags and help message to stdout, since it is easier to grep or pipe.
 	flag.CommandLine.SetOutput(os.Stdout)
 	flag.Usage = usage

app/vmstorage/main.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/VictoriaMetrics/VictoriaMetrics/app/vmstorage/servers"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/buildinfo"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envflag"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
@@ -79,6 +80,15 @@ var (
 )
 
 func main() {
+	// vmstoage is optimized for reduced memory allocations,
+	// so it can run with the reduced GOGC in order to reduce the used memory,
+	// while keeping CPU usage spent in GC at low levels.
+	//
+	// Some workloads may need increased GOGC values. Then such values can be set via GOGC environment variable.
+	// It is recommended increasing GOGC if go_memstats_gc_cpu_fraction metric exposed at /metrics page
+	// exceeds 0.05 for extended periods of time.
+	cgroup.SetGOGC(30)
+
 	// Write flags and help message to stdout, since it is easier to grep or pipe.
 	flag.CommandLine.SetOutput(os.Stdout)
 	flag.Usage = usage

docs/changelog/CHANGELOG.md

@@ -19,6 +19,7 @@ See also [LTS releases](https://docs.victoriametrics.com/lts-releases/).
 ## tip
 
 * FEATURE: [vminsert](https://docs.victoriametrics.com/vminsert/): Storage nodes defined in `-storageNode` are now sorted, ensuring that varying node orders across different vminsert instances do not result in inconsistent replication.
+* FEATURE: all the VictoriaMetrics components: increase the default value for [`GOGC`](https://tip.golang.org/doc/gc-guide#GOGC) from `30` to `100`. This should reduce CPU usage at the cost of slightly higher memory usage. [Single-node VictoriaMetrics](https://docs.victoriametrics.com/), [vmagent](https://docs.victoriametrics.com/vmagent/) and [vmstorage](https://docs.victoriametrics.com/cluster-victoriametrics/#architecture-overview) components continue using `GOGC=30`, since they are optimized for low memory allocations and low memory usage, so they do not benefit from the increased GOGC value too much. It is possible to override the default `GOGC` value in any VictoriaMetrics component by setting `GOGC` environment variable to the desired value. For example, `GOGC=200 ./path/to/vmagent` starts `vmagent` with `GOGC=200`. See [these docs](https://tip.golang.org/doc/gc-guide#GOGC) about `GOGC` tuning. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/7902).
 
 * BUGFIX: [vmauth](https://docs.victoriametrics.com/vmauth/): properly set `host` field at debug information formatted with `dump_request_on_errors: true` setting. 
 

lib/cgroup/mem.go

@@ -13,11 +13,8 @@ func GetGOGC() int {
 	return gogc
 }
 
-func init() {
-	initGOGC()
-}
-
-func initGOGC() {
+// SetGOGC sets GOGC to the given value unless it is already set via environment variable.
+func SetGOGC(gogcNew int) {
 	if v := os.Getenv("GOGC"); v != "" {
 		n, err := strconv.ParseFloat(v, 64)
 		if err != nil {
@@ -25,12 +22,7 @@ func initGOGC() {
 		}
 		gogc = int(n)
 	} else {
-		// Use lower GOGC if it isn't set yet.
-		// This should reduce memory usage for typical workloads for VictoriaMetrics components
-		// at the cost of increased CPU usage.
-		// It is recommended increasing GOGC if go_memstats_gc_cpu_fraction exceeds 0.05 for extended periods of time.
-		gogc = 30
-		debug.SetGCPercent(gogc)
+		debug.SetGCPercent(gogcNew)
 	}
 }