crawler: Remove waitForLowActiveIO (#10667)

Only use dynamic delays for the crawler. Even though the max wait was 1 second the number 
of waits could severely impact crawler speed.

Instead of relying on a global metric, we use the stateless local delays to keep the crawler 
running at a speed more adjusted to current conditions.

The only case we keep it is before bitrot checks when enabled.

cmd/data-crawler.go

@@ -140,7 +140,6 @@ type folderScanner struct {
 	oldCache   dataUsageCache
 	newCache   dataUsageCache
 	withFilter *bloomFilter
-	waitForLowActiveIO func()
 
 	dataUsageCrawlMult  float64
 	dataUsageCrawlDebug bool
@@ -155,7 +154,7 @@ type folderScanner struct {
 // The returned cache will always be valid, but may not be updated from the existing.
 // Before each operation waitForLowActiveIO is called which can be used to temporarily halt the crawler.
 // If the supplied context is canceled the function will return at the first chance.
-func crawlDataFolder(ctx context.Context, basePath string, cache dataUsageCache, waitForLowActiveIO func(), getSize getSizeFn) (dataUsageCache, error) {
+func crawlDataFolder(ctx context.Context, basePath string, cache dataUsageCache, getSize getSizeFn) (dataUsageCache, error) {
 	t := UTCNow()
 
 	logPrefix := color.Green("data-usage: ")
@@ -183,7 +182,6 @@ func crawlDataFolder(ctx context.Context, basePath string, cache dataUsageCache,
 		getSize:             getSize,
 		oldCache:            cache,
 		newCache:            dataUsageCache{Info: cache.Info},
-		waitForLowActiveIO:  waitForLowActiveIO,
 		newFolders:          nil,
 		existingFolders:     nil,
 		dataUsageCrawlMult:  delayMult,
@@ -376,7 +374,6 @@ func (f *folderScanner) scanQueuedLevels(ctx context.Context, folders []cachedFo
 				}
 			}
 		}
-		f.waitForLowActiveIO()
 		sleepDuration(dataCrawlSleepPerFolder, f.dataUsageCrawlMult)
 
 		cache := dataUsageEntry{}
@@ -424,7 +421,6 @@ func (f *folderScanner) scanQueuedLevels(ctx context.Context, folders []cachedFo
 				}
 				return nil
 			}
-			f.waitForLowActiveIO()
 			// Dynamic time delay.
 			t := UTCNow()
 
@@ -484,7 +480,9 @@ func (f *folderScanner) scanQueuedLevels(ctx context.Context, folders []cachedFo
 		// If that doesn't bring it back we remove the folder and assume it was deleted.
 		// This means that the next run will not look for it.
 		for k := range existing {
-			f.waitForLowActiveIO()
+			// Dynamic time delay.
+			t := UTCNow()
+
 			bucket, prefix := path2BucketObject(k)
 			if f.dataUsageCrawlDebug {
 				logger.Info(color.Green("folder-scanner:")+" checking disappeared folder: %v/%v", bucket, prefix)
@@ -498,6 +496,7 @@ func (f *folderScanner) scanQueuedLevels(ctx context.Context, folders []cachedFo
 						versionID: versionID,
 					}, madmin.HealItemObject)
 				})
+			sleepDuration(time.Since(t), f.dataUsageCrawlMult)
 
 			if f.dataUsageCrawlDebug && err != nil {
 				logger.Info(color.Green("healObjects:")+" checking returned value %v", err)
@@ -535,7 +534,6 @@ func (f *folderScanner) deepScanFolder(ctx context.Context, folder cachedFolder)
 		default:
 		}
 
-		f.waitForLowActiveIO()
 		if typ&os.ModeDir != 0 {
 			dirStack = append(dirStack, entName)
 			err := readDirFn(path.Join(dirStack...), addDir)

cmd/data-usage_test.go

@@ -62,7 +62,7 @@ func TestDataUsageUpdate(t *testing.T) {
 		return 0, nil
 	}
 
-	got, err := crawlDataFolder(context.Background(), base, dataUsageCache{Info: dataUsageCacheInfo{Name: bucket}}, func() {}, getSize)
+	got, err := crawlDataFolder(context.Background(), base, dataUsageCache{Info: dataUsageCacheInfo{Name: bucket}}, getSize)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -183,7 +183,7 @@ func TestDataUsageUpdate(t *testing.T) {
 		},
 	}
 	createUsageTestFiles(t, base, bucket, files)
-	got, err = crawlDataFolder(context.Background(), base, got, func() {}, getSize)
+	got, err = crawlDataFolder(context.Background(), base, got, getSize)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -268,7 +268,7 @@ func TestDataUsageUpdate(t *testing.T) {
 	}
 	// Changed dir must be picked up in this many cycles.
 	for i := 0; i < dataUsageUpdateDirCycles; i++ {
-		got, err = crawlDataFolder(context.Background(), base, got, func() {}, getSize)
+		got, err = crawlDataFolder(context.Background(), base, got, getSize)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -355,7 +355,7 @@ func TestDataUsageUpdatePrefix(t *testing.T) {
 		}
 		return 0, nil
 	}
-	got, err := crawlDataFolder(context.Background(), base, dataUsageCache{Info: dataUsageCacheInfo{Name: "bucket"}}, func() {}, getSize)
+	got, err := crawlDataFolder(context.Background(), base, dataUsageCache{Info: dataUsageCacheInfo{Name: "bucket"}}, getSize)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -465,7 +465,7 @@ func TestDataUsageUpdatePrefix(t *testing.T) {
 		},
 	}
 	createUsageTestFiles(t, base, "", files)
-	got, err = crawlDataFolder(context.Background(), base, got, func() {}, getSize)
+	got, err = crawlDataFolder(context.Background(), base, got, getSize)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -548,7 +548,7 @@ func TestDataUsageUpdatePrefix(t *testing.T) {
 	}
 	// Changed dir must be picked up in this many cycles.
 	for i := 0; i < dataUsageUpdateDirCycles; i++ {
-		got, err = crawlDataFolder(context.Background(), base, got, func() {}, getSize)
+		got, err = crawlDataFolder(context.Background(), base, got, getSize)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -652,7 +652,7 @@ func TestDataUsageCacheSerialize(t *testing.T) {
 		}
 		return 0, nil
 	}
-	want, err := crawlDataFolder(context.Background(), base, dataUsageCache{Info: dataUsageCacheInfo{Name: bucket}}, func() {}, getSize)
+	want, err := crawlDataFolder(context.Background(), base, dataUsageCache{Info: dataUsageCacheInfo{Name: bucket}}, getSize)
 	if err != nil {
 		t.Fatal(err)
 	}

cmd/fs-v1.go

@@ -327,7 +327,7 @@ func (fs *FSObjects) crawlBucket(ctx context.Context, bucket string, cache dataU
 	}
 
 	// Load bucket info.
-	cache, err = crawlDataFolder(ctx, fs.fsPath, cache, fs.waitForLowActiveIO, func(item crawlItem) (int64, error) {
+	cache, err = crawlDataFolder(ctx, fs.fsPath, cache, func(item crawlItem) (int64, error) {
 		bucket, object := item.bucket, item.objectPath()
 		fsMetaBytes, err := ioutil.ReadFile(pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix, bucket, object, fs.metaJSONFile))
 		if err != nil && !os.IsNotExist(err) {

cmd/xl-storage.go

@@ -372,7 +372,7 @@ func (s *xlStorage) CrawlAndGetDataUsage(ctx context.Context, cache dataUsageCac
 	}
 	opts := globalCrawlerConfig
 
-	dataUsageInfo, err := crawlDataFolder(ctx, s.diskPath, cache, s.waitForLowActiveIO, func(item crawlItem) (int64, error) {
+	dataUsageInfo, err := crawlDataFolder(ctx, s.diskPath, cache, func(item crawlItem) (int64, error) {
 		// Look for `xl.meta/xl.json' at the leaf.
 		if !strings.HasSuffix(item.Path, SlashSeparator+xlStorageFormatFile) &&
 			!strings.HasSuffix(item.Path, SlashSeparator+xlStorageFormatFileV1) {