Merge pull request #4353 from MichaelEischer/tune-gc

Tune Go garbage collector

changelog/unreleased/issue-3328

@@ -0,0 +1,5 @@
+Enhancement: Reduce memory usage by up to 25%
+
+https://github.com/restic/restic/issues/3328
+https://github.com/restic/restic/pull/4352
+https://github.com/restic/restic/pull/4353

cmd/restic/cmd_prune.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"math"
+	"runtime"
 	"sort"
 	"strconv"
 	"strings"
@@ -205,6 +206,9 @@ func runPruneWithRepo(ctx context.Context, opts PruneOptions, gopts GlobalOption
 		return err
 	}
 
+	// Trigger GC to reset garbage collection threshold
+	runtime.GC()
+
 	return doPrune(ctx, opts, gopts, repo, plan)
 }
 

cmd/restic/main.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"os"
 	"runtime"
+	godebug "runtime/debug"
 
 	"github.com/restic/restic/internal/debug"
 	"github.com/restic/restic/internal/options"
@@ -81,7 +82,16 @@ func needsPassword(cmd string) bool {
 
 var logBuffer = bytes.NewBuffer(nil)
 
+func tweakGoGC() {
+	// lower GOGC from 100 to 50, unless it was manually overwritten by the user
+	oldValue := godebug.SetGCPercent(50)
+	if oldValue != 100 {
+		godebug.SetGCPercent(oldValue)
+	}
+}
+
 func main() {
+	tweakGoGC()
 	// install custom global logger into a buffer, if an error occurs
 	// we can show the logs
 	log.SetOutput(logBuffer)

internal/repository/repository.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"runtime"
 	"sort"
 	"sync"
 
@@ -601,6 +602,9 @@ func (r *Repository) LoadIndex(ctx context.Context) error {
 		return err
 	}
 
+	// Trigger GC to reset garbage collection threshold
+	runtime.GC()
+
 	if r.cfg.Version < 2 {
 		// sanity check
 		ctx, cancel := context.WithCancel(ctx)