[#39] node: Add optional profilers

Include settings for block and mutex profilers.
They are disabled by default, as in Go runtime itself.

Signed-off-by: Pavel Karpy <p.karpy@yadro.com>
Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

cmd/frostfs-node/pprof.go

@@ -1,10 +1,19 @@
 package main
 
 import (
+	"runtime"
+
 	profilerconfig "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-node/config/profiler"
 	httputil "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/http"
 )
 
+func initProfilerService(c *cfg) {
+	tuneProfilers(c)
+
+	pprof, _ := pprofComponent(c)
+	pprof.init(c)
+}
+
 func pprofComponent(c *cfg) (*httpComponent, bool) {
 	var updated bool
 	// check if it has been inited before
@@ -13,6 +22,7 @@ func pprofComponent(c *cfg) (*httpComponent, bool) {
 		c.dynamicConfiguration.pprof.cfg = c
 		c.dynamicConfiguration.pprof.name = "pprof"
 		c.dynamicConfiguration.pprof.handler = httputil.Handler()
+		c.dynamicConfiguration.pprof.preReload = tuneProfilers
 		updated = true
 	}
 
@@ -35,3 +45,18 @@ func pprofComponent(c *cfg) (*httpComponent, bool) {
 
 	return c.dynamicConfiguration.pprof, updated
 }
+
+func tuneProfilers(c *cfg) {
+	// Disabled by default, see documentation for
+	// runtime.SetBlockProfileRate() and runtime.SetMutexProfileFraction().
+	blockRate := 0
+	mutexRate := 0
+
+	if profilerconfig.Enabled(c.appCfg) {
+		blockRate = profilerconfig.BlockRate(c.appCfg)
+		mutexRate = profilerconfig.MutexRate(c.appCfg)
+	}
+
+	runtime.SetBlockProfileRate(blockRate)
+	runtime.SetMutexProfileFraction(mutexRate)
+}