Golang : How to get garbage collection data?
Problem :
You have read the previous tutorial on recovering memory and you want to trigger garbage collection manually with runtime/debug.FreeOSMemory()
or calculate the percentage to use with runtime/debug.SetGCPercent()
function, but you need to figure out what are the parameters to take into account and other information such as the last garbage collection time, available heap size, the number of garbage collection and etc.
Solution :
Use runtime.ReadMemStats()
and runtime/debug.ReadGCStats()
functions to gather the garbage collection data.
package main
import (
"fmt"
"runtime"
"runtime/debug"
)
func main() {
s := new(runtime.MemStats)
runtime.ReadMemStats(s)
fmt.Println("Alloc : ", s.Alloc)
fmt.Println("Total Alloc : ", s.TotalAlloc)
fmt.Println("Sys : ", s.Sys)
fmt.Println("Lookups : ", s.Lookups)
// Garbage Collection data
fmt.Println("HeapAlloc : ", s.HeapAlloc)
fmt.Println("Next Garbage Collection : ", s.NextGC)
fmt.Println("Auto garbage collection will happen when HeapAlloc >= NextGC")
fmt.Println("Last Garbage Collection : ", s.LastGC)
fmt.Println("Total number of GC pause : ", s.PauseTotalNs)
// [256]uint64 array
// we will take the first element for this example...you might want to loop the array
fmt.Println("Most recent pause : ", s.PauseNs[0])
fmt.Println("Recent pause end times : ", s.PauseEnd[0])
fmt.Println("Number of Garbage Collections : ", s.NumGC)
fmt.Println("Is Garbage Collection enabled? : ", s.EnableGC)
fmt.Println("Is Garbage Collection debug enabled? : ", s.DebugGC)
// ---------------------------
gcs := new(debug.GCStats)
debug.ReadGCStats(gcs)
fmt.Println("Last Garbage Collection : ", gcs.LastGC)
fmt.Println("Number of Garbage Collection : ", gcs.NumGC)
fmt.Println("Total pause for all collections : ", gcs.PauseTotal)
// []time.Duration array
fmt.Println("Most recent pause history : ", gcs.Pause)
// []time.Time array
fmt.Println("Most recent pause end times history : ", gcs.PauseEnd)
// []time.Duration array
// Pause Quantiles == values taken at regular interval
fmt.Println("Most recent pause quantiles history : ", gcs.PauseQuantiles)
}
References :
http://golang.org/pkg/runtime/debug/#FreeOSMemory
http://golang.org/pkg/runtime/debug/#ReadGCStats
See also : Golang : Ways to recover memory during run time.
By Adam Ng
IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.
Advertisement
Tutorials
+6.3k Golang : Ackermann function example
+4.2k Golang : Dealing with backquote
+7.7k Golang : Convert(cast) string to int64
+6.6k Golang : Build and compile multiple source files
+7.6k Golang : Random Rune generator
+3k Golang : Calculate a pip value and distance to target profit example
+19k Golang : Get ASCII code from a key press(cross-platform) example
+36.5k Golang : Get hardware information such as disk, memory and CPU usage
+3.9k Swift : Convert string array to array example
+15.1k Golang : Accept input from user with fmt.Scanf skipped white spaces and how to fix it
+7.9k Golang : Get login name from environment and prompt for password
+5.4k Golang : Set horizontal, vertical scroll bars policies and disable interaction on Qt image