Use errgroups instead of sync.WaitGroup as needed (#8354)

cmd/bucket-handlers.go

@@ -71,8 +71,8 @@ func initFederatorBackend(objLayer ObjectLayer) {
 	// Add buckets that are not registered with the DNS
 	g := errgroup.WithNErrs(len(b))
 	for index := range b {
-		index := index
 		bucketSet.Add(b[index].Name)
+		index := index
 		g.Go(func() error {
 			r, gerr := globalDNSConfig.Get(b[index].Name)
 			if gerr != nil {
@@ -99,7 +99,6 @@ func initFederatorBackend(objLayer ObjectLayer) {
 	// Remove buckets that are in DNS for this server, but aren't local
 	for index := range dnsBuckets {
 		index := index
-
 		g.Go(func() error {
 			// This is a local bucket that exists, so we can continue
 			if bucketSet.Contains(dnsBuckets[index].Key) {

cmd/disk-cache.go

@@ -16,6 +16,7 @@ import (
 	"github.com/minio/minio/cmd/config/cache"
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/color"
+	"github.com/minio/minio/pkg/sync/errgroup"
 	"github.com/minio/minio/pkg/wildcard"
 )
 
@@ -450,36 +451,32 @@ func checkAtimeSupport(dir string) (err error) {
 func (c *cacheObjects) migrateCacheFromV1toV2(ctx context.Context) {
 	logStartupMessage(color.Blue("Cache migration initiated ...."))
 
-	var wg sync.WaitGroup
-	errs := make([]error, len(c.cache))
-	for i, dc := range c.cache {
+	g := errgroup.WithNErrs(len(c.cache))
+	for index, dc := range c.cache {
 		if dc == nil {
 			continue
 		}
-		wg.Add(1)
-		// start migration from V1 to V2
-		go func(ctx context.Context, dc *diskCache, errs []error, idx int) {
-			defer wg.Done()
-			if err := migrateOldCache(ctx, dc); err != nil {
-				errs[idx] = err
-				logger.LogIf(ctx, err)
-				return
-			}
-			// start purge routine after migration completes.
-			go dc.purge()
-		}(ctx, dc, errs, i)
+		index := index
+		g.Go(func() error {
+			// start migration from V1 to V2
+			return migrateOldCache(ctx, c.cache[index])
+		}, index)
 	}
-	wg.Wait()
 
 	errCnt := 0
-	for _, err := range errs {
+	for index, err := range g.Wait() {
 		if err != nil {
 			errCnt++
+			logger.LogIf(ctx, err)
+			continue
 		}
+		go c.cache[index].purge()
 	}
+
 	if errCnt > 0 {
 		return
 	}
+
 	// update migration status
 	c.migMutex.Lock()
 	defer c.migMutex.Unlock()

cmd/format-xl.go

@@ -23,12 +23,12 @@ import (
 	"fmt"
 	"io/ioutil"
 	"reflect"
-	"sync"
 
 	"encoding/hex"
 
 	humanize "github.com/dustin/go-humanize"
 	"github.com/minio/minio/cmd/logger"
+	"github.com/minio/minio/pkg/sync/errgroup"
 	sha256 "github.com/minio/sha256-simd"
 )
 
@@ -315,40 +315,30 @@ func quorumUnformattedDisks(errs []error) bool {
 
 // loadFormatXLAll - load all format config from all input disks in parallel.
 func loadFormatXLAll(storageDisks []StorageAPI) ([]*formatXLV3, []error) {
-	// Initialize sync waitgroup.
-	var wg sync.WaitGroup
-
 	// Initialize list of errors.
-	var sErrs = make([]error, len(storageDisks))
+	g := errgroup.WithNErrs(len(storageDisks))
 
 	// Initialize format configs.
 	var formats = make([]*formatXLV3, len(storageDisks))
 
 	// Load format from each disk in parallel
-	for index, disk := range storageDisks {
-		if disk == nil {
-			sErrs[index] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		// Launch go-routine per disk.
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-
-			format, lErr := loadFormatXL(disk)
-			if lErr != nil {
-				sErrs[index] = lErr
-				return
+	for index := range storageDisks {
+		index := index
+		g.Go(func() error {
+			if storageDisks[index] == nil {
+				return errDiskNotFound
+			}
+			format, err := loadFormatXL(storageDisks[index])
+			if err != nil {
+				return err
 			}
 			formats[index] = format
-		}(index, disk)
+			return nil
+		}, index)
 	}
 
-	// Wait for all go-routines to finish.
-	wg.Wait()
-
-	// Return all formats and nil
-	return formats, sErrs
+	// Return all formats and errors if any.
+	return formats, g.Wait()
 }
 
 func saveFormatXL(disk StorageAPI, format interface{}) error {
@@ -643,28 +633,22 @@ func formatXLV3Check(reference *formatXLV3, format *formatXLV3) error {
 
 // saveFormatXLAll - populates `format.json` on disks in its order.
 func saveFormatXLAll(ctx context.Context, storageDisks []StorageAPI, formats []*formatXLV3) error {
-	var errs = make([]error, len(storageDisks))
-
-	var wg sync.WaitGroup
+	g := errgroup.WithNErrs(len(storageDisks))
 
 	// Write `format.json` to all disks.
-	for index, disk := range storageDisks {
-		if formats[index] == nil || disk == nil {
-			errs[index] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		go func(index int, disk StorageAPI, format *formatXLV3) {
-			defer wg.Done()
-			errs[index] = saveFormatXL(disk, format)
-		}(index, disk, formats[index])
+	for index := range storageDisks {
+		index := index
+		g.Go(func() error {
+			if formats[index] == nil || storageDisks[index] == nil {
+				return errDiskNotFound
+			}
+			return saveFormatXL(storageDisks[index], formats[index])
+		}, index)
 	}
 
-	// Wait for the routines to finish.
-	wg.Wait()
-
 	writeQuorum := len(storageDisks)/2 + 1
-	return reduceWriteQuorumErrs(ctx, errs, nil, writeQuorum)
+	// Wait for the routines to finish.
+	return reduceWriteQuorumErrs(ctx, g.Wait(), nil, writeQuorum)
 }
 
 // relinquishes the underlying connection for all storage disks.
@@ -682,17 +666,19 @@ func closeStorageDisks(storageDisks []StorageAPI) {
 func initStorageDisksWithErrors(endpoints EndpointList) ([]StorageAPI, []error) {
 	// Bootstrap disks.
 	storageDisks := make([]StorageAPI, len(endpoints))
-	errs := make([]error, len(endpoints))
-	var wg sync.WaitGroup
-	for index, endpoint := range endpoints {
-		wg.Add(1)
-		go func(index int, endpoint Endpoint) {
-			defer wg.Done()
-			storageDisks[index], errs[index] = newStorageAPI(endpoint)
-		}(index, endpoint)
+	g := errgroup.WithNErrs(len(endpoints))
+	for index := range endpoints {
+		index := index
+		g.Go(func() error {
+			storageDisk, err := newStorageAPI(endpoints[index])
+			if err != nil {
+				return err
+			}
+			storageDisks[index] = storageDisk
+			return nil
+		}, index)
 	}
-	wg.Wait()
-	return storageDisks, errs
+	return storageDisks, g.Wait()
 }
 
 // formatXLV3ThisEmpty - find out if '.This' field is empty
@@ -793,31 +779,24 @@ func initFormatXLMetaVolume(storageDisks []StorageAPI, formats []*formatXLV3) er
 	// This happens for the first time, but keep this here since this
 	// is the only place where it can be made expensive optimizing all
 	// other calls. Create minio meta volume, if it doesn't exist yet.
-	var wg sync.WaitGroup
 
 	// Initialize errs to collect errors inside go-routine.
-	var errs = make([]error, len(storageDisks))
+	g := errgroup.WithNErrs(len(storageDisks))
 
 	// Initialize all disks in parallel.
-	for index, disk := range storageDisks {
-		if formats[index] == nil || disk == nil {
-			// Ignore create meta volume on disks which are not found.
-			continue
-		}
-		wg.Add(1)
-		go func(index int, disk StorageAPI) {
-			// Indicate this wait group is done.
-			defer wg.Done()
-
-			errs[index] = makeFormatXLMetaVolumes(disk)
-		}(index, disk)
+	for index := range storageDisks {
+		index := index
+		g.Go(func() error {
+			if formats[index] == nil || storageDisks[index] == nil {
+				// Ignore create meta volume on disks which are not found.
+				return nil
+			}
+			return makeFormatXLMetaVolumes(storageDisks[index])
+		}, index)
 	}
 
-	// Wait for all cleanup to finish.
-	wg.Wait()
-
 	// Return upon first error.
-	for _, err := range errs {
+	for _, err := range g.Wait() {
 		if err == nil {
 			continue
 		}

cmd/notification.go

@@ -38,6 +38,7 @@ import (
 	"github.com/minio/minio/pkg/madmin"
 	xnet "github.com/minio/minio/pkg/net"
 	"github.com/minio/minio/pkg/policy"
+	"github.com/minio/minio/pkg/sync/errgroup"
 )
 
 // NotificationSys - notification system.
@@ -72,24 +73,6 @@ type NotificationPeerErr struct {
 	Err  error     // Error returned by the remote peer for an rpc call
 }
 
-// DeleteBucket - calls DeleteBucket RPC call on all peers.
-func (sys *NotificationSys) DeleteBucket(ctx context.Context, bucketName string) {
-	go func() {
-		var wg sync.WaitGroup
-		for _, client := range sys.peerClients {
-			wg.Add(1)
-			go func(client *peerRESTClient) {
-				defer wg.Done()
-				if err := client.DeleteBucket(bucketName); err != nil {
-					logger.GetReqInfo(ctx).AppendTags("remotePeer", client.host.Name)
-					logger.LogIf(ctx, err)
-				}
-			}(client)
-		}
-		wg.Wait()
-	}()
-}
-
 // A NotificationGroup is a collection of goroutines working on subtasks that are part of
 // the same overall task.
 //
@@ -438,43 +421,44 @@ func (sys *NotificationSys) SignalService(sig serviceSignal) []NotificationPeerE
 // ServerInfo - calls ServerInfo RPC call on all peers.
 func (sys *NotificationSys) ServerInfo(ctx context.Context) []ServerInfo {
 	serverInfo := make([]ServerInfo, len(sys.peerClients))
-	var wg sync.WaitGroup
+
+	g := errgroup.WithNErrs(len(sys.peerClients))
 	for index, client := range sys.peerClients {
 		if client == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(idx int, client *peerRESTClient) {
-			defer wg.Done()
+		index := index
+		g.Go(func() error {
 			// Try to fetch serverInfo remotely in three attempts.
 			for i := 0; i < 3; i++ {
-				info, err := client.ServerInfo()
-				if err == nil {
-					serverInfo[idx] = ServerInfo{
-						Addr: client.host.String(),
-						Data: &info,
-					}
-					return
+				serverInfo[index] = ServerInfo{
+					Addr: sys.peerClients[index].host.String(),
 				}
-				serverInfo[idx] = ServerInfo{
-					Addr:  client.host.String(),
-					Data:  &info,
-					Error: err.Error(),
+				info, err := sys.peerClients[index].ServerInfo()
+				if err != nil {
+					serverInfo[index].Error = err.Error()
 				}
+				serverInfo[index].Data = &info
 				// Last iteration log the error.
 				if i == 2 {
-					reqInfo := (&logger.ReqInfo{}).AppendTags("peerAddress", client.host.String())
-					ctx := logger.SetReqInfo(ctx, reqInfo)
-					logger.LogIf(ctx, err)
+					return err
 				}
 				// Wait for one second and no need wait after last attempt.
 				if i < 2 {
 					time.Sleep(1 * time.Second)
 				}
 			}
-		}(index, client)
+			return nil
+		}, index)
+	}
+	for index, err := range g.Wait() {
+		if err != nil {
+			addr := sys.peerClients[index].host.String()
+			reqInfo := (&logger.ReqInfo{}).AppendTags("peerAddress", addr)
+			ctx := logger.SetReqInfo(ctx, reqInfo)
+			logger.LogIf(ctx, err)
+		}
 	}
-	wg.Wait()
 	return serverInfo
 }
 
@@ -482,166 +466,163 @@ func (sys *NotificationSys) ServerInfo(ctx context.Context) []ServerInfo {
 func (sys *NotificationSys) GetLocks(ctx context.Context) []*PeerLocks {
 
 	locksResp := make([]*PeerLocks, len(sys.peerClients))
-	var wg sync.WaitGroup
+	g := errgroup.WithNErrs(len(sys.peerClients))
 	for index, client := range sys.peerClients {
 		if client == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(idx int, client *peerRESTClient) {
-			defer wg.Done()
+		index := index
+		g.Go(func() error {
 			// Try to fetch serverInfo remotely in three attempts.
 			for i := 0; i < 3; i++ {
-				serverLocksResp, err := client.GetLocks()
+				serverLocksResp, err := sys.peerClients[index].GetLocks()
 				if err == nil {
-					locksResp[idx] = &PeerLocks{
-						Addr:  client.host.String(),
+					locksResp[index] = &PeerLocks{
+						Addr:  sys.peerClients[index].host.String(),
 						Locks: serverLocksResp,
 					}
-					return
+					return nil
 				}
 
 				// Last iteration log the error.
 				if i == 2 {
-					reqInfo := (&logger.ReqInfo{}).AppendTags("peerAddress", client.host.String())
-					ctx := logger.SetReqInfo(ctx, reqInfo)
-					logger.LogOnceIf(ctx, err, client.host.String())
+					return err
 				}
 				// Wait for one second and no need wait after last attempt.
 				if i < 2 {
 					time.Sleep(1 * time.Second)
 				}
 			}
-		}(index, client)
+			return nil
+		}, index)
+	}
+	for index, err := range g.Wait() {
+		reqInfo := (&logger.ReqInfo{}).AppendTags("peerAddress",
+			sys.peerClients[index].host.String())
+		ctx := logger.SetReqInfo(ctx, reqInfo)
+		logger.LogOnceIf(ctx, err, sys.peerClients[index].host.String())
 	}
-	wg.Wait()
 	return locksResp
 }
 
 // SetBucketPolicy - calls SetBucketPolicy RPC call on all peers.
 func (sys *NotificationSys) SetBucketPolicy(ctx context.Context, bucketName string, bucketPolicy *policy.Policy) {
 	go func() {
-		var wg sync.WaitGroup
-		for _, client := range sys.peerClients {
+		ng := WithNPeers(len(sys.peerClients))
+		for idx, client := range sys.peerClients {
 			if client == nil {
 				continue
 			}
-			wg.Add(1)
-			go func(client *peerRESTClient) {
-				defer wg.Done()
-				if err := client.SetBucketPolicy(bucketName, bucketPolicy); err != nil {
-					logger.GetReqInfo(ctx).AppendTags("remotePeer", client.host.Name)
-					logger.LogIf(ctx, err)
-				}
-			}(client)
+			client := client
+			ng.Go(ctx, func() error {
+				return client.SetBucketPolicy(bucketName, bucketPolicy)
+			}, idx, *client.host)
+		}
+		ng.Wait()
+	}()
+}
+
+// DeleteBucket - calls DeleteBucket RPC call on all peers.
+func (sys *NotificationSys) DeleteBucket(ctx context.Context, bucketName string) {
+	go func() {
+		ng := WithNPeers(len(sys.peerClients))
+		for idx, client := range sys.peerClients {
+			if client == nil {
+				continue
+			}
+			client := client
+			ng.Go(ctx, func() error {
+				return client.DeleteBucket(bucketName)
+			}, idx, *client.host)
 		}
-		wg.Wait()
+		ng.Wait()
 	}()
 }
 
 // RemoveBucketPolicy - calls RemoveBucketPolicy RPC call on all peers.
 func (sys *NotificationSys) RemoveBucketPolicy(ctx context.Context, bucketName string) {
 	go func() {
-		var wg sync.WaitGroup
-		for _, client := range sys.peerClients {
+		ng := WithNPeers(len(sys.peerClients))
+		for idx, client := range sys.peerClients {
 			if client == nil {
 				continue
 			}
-			wg.Add(1)
-			go func(client *peerRESTClient) {
-				defer wg.Done()
-				if err := client.RemoveBucketPolicy(bucketName); err != nil {
-					logger.GetReqInfo(ctx).AppendTags("remotePeer", client.host.Name)
-					logger.LogIf(ctx, err)
-				}
-			}(client)
+			client := client
+			ng.Go(ctx, func() error {
+				return client.RemoveBucketPolicy(bucketName)
+			}, idx, *client.host)
 		}
-		wg.Wait()
+		ng.Wait()
 	}()
 }
 
 // SetBucketLifecycle - calls SetBucketLifecycle on all peers.
-func (sys *NotificationSys) SetBucketLifecycle(ctx context.Context, bucketName string, bucketLifecycle *lifecycle.Lifecycle) {
+func (sys *NotificationSys) SetBucketLifecycle(ctx context.Context, bucketName string,
+	bucketLifecycle *lifecycle.Lifecycle) {
 	go func() {
-		var wg sync.WaitGroup
-		for _, client := range sys.peerClients {
+		ng := WithNPeers(len(sys.peerClients))
+		for idx, client := range sys.peerClients {
 			if client == nil {
 				continue
 			}
-			wg.Add(1)
-			go func(client *peerRESTClient) {
-				defer wg.Done()
-				if err := client.SetBucketLifecycle(bucketName, bucketLifecycle); err != nil {
-					logger.GetReqInfo(ctx).AppendTags("remotePeer", client.host.Name)
-					logger.LogIf(ctx, err)
-				}
-			}(client)
+			client := client
+			ng.Go(ctx, func() error {
+				return client.SetBucketLifecycle(bucketName, bucketLifecycle)
+			}, idx, *client.host)
 		}
-		wg.Wait()
+		ng.Wait()
 	}()
 }
 
 // RemoveBucketLifecycle - calls RemoveLifecycle on all peers.
 func (sys *NotificationSys) RemoveBucketLifecycle(ctx context.Context, bucketName string) {
 	go func() {
-		var wg sync.WaitGroup
-		for _, client := range sys.peerClients {
+		ng := WithNPeers(len(sys.peerClients))
+		for idx, client := range sys.peerClients {
 			if client == nil {
 				continue
 			}
-			wg.Add(1)
-			go func(client *peerRESTClient) {
-				defer wg.Done()
-				if err := client.RemoveBucketLifecycle(bucketName); err != nil {
-					logger.GetReqInfo(ctx).AppendTags("remotePeer", client.host.Name)
-					logger.LogIf(ctx, err)
-				}
-			}(client)
+			client := client
+			ng.Go(ctx, func() error {
+				return client.RemoveBucketLifecycle(bucketName)
+			}, idx, *client.host)
 		}
-		wg.Wait()
+		ng.Wait()
 	}()
 }
 
 // PutBucketNotification - calls PutBucketNotification RPC call on all peers.
 func (sys *NotificationSys) PutBucketNotification(ctx context.Context, bucketName string, rulesMap event.RulesMap) {
 	go func() {
-		var wg sync.WaitGroup
-		for _, client := range sys.peerClients {
+		ng := WithNPeers(len(sys.peerClients))
+		for idx, client := range sys.peerClients {
 			if client == nil {
 				continue
 			}
-			wg.Add(1)
-			go func(client *peerRESTClient, rulesMap event.RulesMap) {
-				defer wg.Done()
-				if err := client.PutBucketNotification(bucketName, rulesMap); err != nil {
-					logger.GetReqInfo(ctx).AppendTags("remotePeer", client.host.Name)
-					logger.LogIf(ctx, err)
-				}
-			}(client, rulesMap.Clone())
+			client := client
+			ng.Go(ctx, func() error {
+				return client.PutBucketNotification(bucketName, rulesMap)
+			}, idx, *client.host)
 		}
-		wg.Wait()
+		ng.Wait()
 	}()
 }
 
 // ListenBucketNotification - calls ListenBucketNotification RPC call on all peers.
-func (sys *NotificationSys) ListenBucketNotification(ctx context.Context, bucketName string, eventNames []event.Name, pattern string,
-	targetID event.TargetID, localPeer xnet.Host) {
+func (sys *NotificationSys) ListenBucketNotification(ctx context.Context, bucketName string,
+	eventNames []event.Name, pattern string, targetID event.TargetID, localPeer xnet.Host) {
 	go func() {
-		var wg sync.WaitGroup
-		for _, client := range sys.peerClients {
+		ng := WithNPeers(len(sys.peerClients))
+		for idx, client := range sys.peerClients {
 			if client == nil {
 				continue
 			}
-			wg.Add(1)
-			go func(client *peerRESTClient) {
-				defer wg.Done()
-				if err := client.ListenBucketNotification(bucketName, eventNames, pattern, targetID, localPeer); err != nil {
-					logger.GetReqInfo(ctx).AppendTags("remotePeer", client.host.Name)
-					logger.LogIf(ctx, err)
-				}
-			}(client)
+			client := client
+			ng.Go(ctx, func() error {
+				return client.ListenBucketNotification(bucketName, eventNames, pattern, targetID, localPeer)
+			}, idx, *client.host)
 		}
-		wg.Wait()
+		ng.Wait()
 	}()
 }
 
@@ -981,78 +962,90 @@ func (sys *NotificationSys) CollectNetPerfInfo(size int64) map[string][]ServerNe
 // DrivePerfInfo - Drive speed (read and write) information
 func (sys *NotificationSys) DrivePerfInfo(size int64) []madmin.ServerDrivesPerfInfo {
 	reply := make([]madmin.ServerDrivesPerfInfo, len(sys.peerClients))
-	var wg sync.WaitGroup
-	for i, client := range sys.peerClients {
+
+	g := errgroup.WithNErrs(len(sys.peerClients))
+	for index, client := range sys.peerClients {
 		if client == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(client *peerRESTClient, idx int) {
-			defer wg.Done()
-			di, err := client.DrivePerfInfo(size)
-			if err != nil {
-				reqInfo := (&logger.ReqInfo{}).AppendTags("remotePeer", client.host.String())
-				ctx := logger.SetReqInfo(context.Background(), reqInfo)
-				logger.LogIf(ctx, err)
-				di.Addr = client.host.String()
-				di.Error = err.Error()
-			}
-			reply[idx] = di
-		}(client, i)
+		index := index
+		g.Go(func() error {
+			var err error
+			reply[index], err = sys.peerClients[index].DrivePerfInfo(size)
+			return err
+		}, index)
+	}
+
+	for index, err := range g.Wait() {
+		if err != nil {
+			addr := sys.peerClients[index].host.String()
+			reqInfo := (&logger.ReqInfo{}).AppendTags("remotePeer", addr)
+			ctx := logger.SetReqInfo(context.Background(), reqInfo)
+			logger.LogIf(ctx, err)
+			reply[index].Addr = addr
+			reply[index].Error = err.Error()
+		}
 	}
-	wg.Wait()
 	return reply
 }
 
 // MemUsageInfo - Mem utilization information
 func (sys *NotificationSys) MemUsageInfo() []ServerMemUsageInfo {
 	reply := make([]ServerMemUsageInfo, len(sys.peerClients))
-	var wg sync.WaitGroup
-	for i, client := range sys.peerClients {
+
+	g := errgroup.WithNErrs(len(sys.peerClients))
+	for index, client := range sys.peerClients {
 		if client == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(client *peerRESTClient, idx int) {
-			defer wg.Done()
-			memi, err := client.MemUsageInfo()
-			if err != nil {
-				reqInfo := (&logger.ReqInfo{}).AppendTags("remotePeer", client.host.String())
-				ctx := logger.SetReqInfo(context.Background(), reqInfo)
-				logger.LogIf(ctx, err)
-				memi.Addr = client.host.String()
-				memi.Error = err.Error()
-			}
-			reply[idx] = memi
-		}(client, i)
+		index := index
+		g.Go(func() error {
+			var err error
+			reply[index], err = sys.peerClients[index].MemUsageInfo()
+			return err
+		}, index)
+	}
+
+	for index, err := range g.Wait() {
+		if err != nil {
+			addr := sys.peerClients[index].host.String()
+			reqInfo := (&logger.ReqInfo{}).AppendTags("remotePeer", addr)
+			ctx := logger.SetReqInfo(context.Background(), reqInfo)
+			logger.LogIf(ctx, err)
+			reply[index].Addr = addr
+			reply[index].Error = err.Error()
+		}
 	}
-	wg.Wait()
 	return reply
 }
 
 // CPULoadInfo - CPU utilization information
 func (sys *NotificationSys) CPULoadInfo() []ServerCPULoadInfo {
 	reply := make([]ServerCPULoadInfo, len(sys.peerClients))
-	var wg sync.WaitGroup
-	for i, client := range sys.peerClients {
+
+	g := errgroup.WithNErrs(len(sys.peerClients))
+	for index, client := range sys.peerClients {
 		if client == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(client *peerRESTClient, idx int) {
-			defer wg.Done()
-			cpui, err := client.CPULoadInfo()
-			if err != nil {
-				reqInfo := (&logger.ReqInfo{}).AppendTags("remotePeer", client.host.String())
-				ctx := logger.SetReqInfo(context.Background(), reqInfo)
-				logger.LogIf(ctx, err)
-				cpui.Addr = client.host.String()
-				cpui.Error = err.Error()
-			}
-			reply[idx] = cpui
-		}(client, i)
+		index := index
+		g.Go(func() error {
+			var err error
+			reply[index], err = sys.peerClients[index].CPULoadInfo()
+			return err
+		}, index)
+	}
+
+	for index, err := range g.Wait() {
+		if err != nil {
+			addr := sys.peerClients[index].host.String()
+			reqInfo := (&logger.ReqInfo{}).AppendTags("remotePeer", addr)
+			ctx := logger.SetReqInfo(context.Background(), reqInfo)
+			logger.LogIf(ctx, err)
+			reply[index].Addr = addr
+			reply[index].Error = err.Error()
+		}
 	}
-	wg.Wait()
 	return reply
 }
 

cmd/posix-list-dir_test.go

@@ -129,8 +129,8 @@ func setupTestReadDirGeneric(t *testing.T) (testResults []result) {
 
 // Test to read non-empty directory with symlinks.
 func setupTestReadDirSymlink(t *testing.T) (testResults []result) {
-	if runtime.GOOS != "Windows" {
-		t.Log("symlinks not available on windows")
+	if runtime.GOOS == globalWindowsOSName {
+		t.Skip("symlinks not available on windows")
 		return nil
 	}
 	dir := mustSetupDir(t)

cmd/xl-sets.go

@@ -306,19 +306,21 @@ func newXLSets(endpoints EndpointList, format *formatXLV3, setCount int, drivesP
 // StorageInfo - combines output of StorageInfo across all erasure coded object sets.
 func (s *xlSets) StorageInfo(ctx context.Context) StorageInfo {
 	var storageInfo StorageInfo
-	var wg sync.WaitGroup
 
 	storageInfos := make([]StorageInfo, len(s.sets))
 	storageInfo.Backend.Type = BackendErasure
-	for index, set := range s.sets {
-		wg.Add(1)
-		go func(id int, set *xlObjects) {
-			defer wg.Done()
-			storageInfos[id] = set.StorageInfo(ctx)
-		}(index, set)
+
+	g := errgroup.WithNErrs(len(s.sets))
+	for index := range s.sets {
+		index := index
+		g.Go(func() error {
+			storageInfos[index] = s.sets[index].StorageInfo(ctx)
+			return nil
+		}, index)
 	}
+
 	// Wait for the go routines.
-	wg.Wait()
+	g.Wait()
 
 	for _, lstorageInfo := range storageInfos {
 		storageInfo.Used += lstorageInfo.Used
@@ -458,11 +460,12 @@ func undoMakeBucketSets(bucket string, sets []*xlObjects, errs []error) {
 	// Undo previous make bucket entry on all underlying sets.
 	for index := range sets {
 		index := index
-		if errs[index] == nil {
-			g.Go(func() error {
+		g.Go(func() error {
+			if errs[index] == nil {
 				return sets[index].DeleteBucket(context.Background(), bucket)
-			}, index)
-		}
+			}
+			return nil
+		}, index)
 	}
 
 	// Wait for all delete bucket to finish.
@@ -618,11 +621,12 @@ func undoDeleteBucketSets(bucket string, sets []*xlObjects, errs []error) {
 	// Undo previous delete bucket on all underlying sets.
 	for index := range sets {
 		index := index
-		if errs[index] == nil {
-			g.Go(func() error {
+		g.Go(func() error {
+			if errs[index] == nil {
 				return sets[index].MakeBucketWithLocation(context.Background(), bucket, "")
-			}, index)
-		}
+			}
+			return nil
+		}, index)
 	}
 
 	g.Wait()
@@ -742,19 +746,24 @@ func (s *xlSets) CopyObject(ctx context.Context, srcBucket, srcObject, destBucke
 func listDirSetsFactory(ctx context.Context, sets ...*xlObjects) ListDirFunc {
 	listDirInternal := func(bucket, prefixDir, prefixEntry string, disks []StorageAPI) (mergedEntries []string) {
 		var diskEntries = make([][]string, len(disks))
-		var wg sync.WaitGroup
+		g := errgroup.WithNErrs(len(disks))
 		for index, disk := range disks {
 			if disk == nil {
 				continue
 			}
-			wg.Add(1)
-			go func(index int, disk StorageAPI) {
-				defer wg.Done()
-				diskEntries[index], _ = disk.ListDir(bucket, prefixDir, -1, xlMetaJSONFile)
-			}(index, disk)
+			index := index
+			g.Go(func() error {
+				var err error
+				diskEntries[index], err = disks[index].ListDir(bucket, prefixDir, -1, xlMetaJSONFile)
+				return err
+			}, index)
 		}
 
-		wg.Wait()
+		for _, err := range g.Wait() {
+			if err != nil {
+				logger.LogIf(ctx, err)
+			}
+		}
 
 		// Find elements in entries which are not in mergedEntries
 		for _, entries := range diskEntries {
@@ -1405,21 +1414,21 @@ func isTestSetup(infos []DiskInfo, errs []error) bool {
 
 func getAllDiskInfos(storageDisks []StorageAPI) ([]DiskInfo, []error) {
 	infos := make([]DiskInfo, len(storageDisks))
-	errs := make([]error, len(storageDisks))
-	var wg sync.WaitGroup
-	for i := range storageDisks {
-		if storageDisks[i] == nil {
-			errs[i] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		go func(i int) {
-			defer wg.Done()
-			infos[i], errs[i] = storageDisks[i].DiskInfo()
-		}(i)
+	g := errgroup.WithNErrs(len(storageDisks))
+	for index := range storageDisks {
+		index := index
+		g.Go(func() error {
+			var err error
+			if storageDisks[index] != nil {
+				infos[index], err = storageDisks[index].DiskInfo()
+			} else {
+				// Disk not found.
+				err = errDiskNotFound
+			}
+			return err
+		}, index)
 	}
-	wg.Wait()
-	return infos, errs
+	return infos, g.Wait()
 }
 
 // Mark root disks as down so as not to heal them.

cmd/xl-v1-bucket.go

@@ -19,12 +19,12 @@ package cmd
 import (
 	"context"
 	"sort"
-	"sync"
 
 	"github.com/minio/minio-go/v6/pkg/s3utils"
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/lifecycle"
 	"github.com/minio/minio/pkg/policy"
+	"github.com/minio/minio/pkg/sync/errgroup"
 )
 
 // list all errors that can be ignore in a bucket operation.
@@ -42,83 +42,71 @@ func (xl xlObjects) MakeBucketWithLocation(ctx context.Context, bucket, location
 		return BucketNameInvalid{Bucket: bucket}
 	}
 
-	// Initialize sync waitgroup.
-	var wg sync.WaitGroup
+	storageDisks := xl.getDisks()
 
-	// Initialize list of errors.
-	var dErrs = make([]error, len(xl.getDisks()))
+	g := errgroup.WithNErrs(len(storageDisks))
 
 	// Make a volume entry on all underlying storage disks.
-	for index, disk := range xl.getDisks() {
-		if disk == nil {
-			dErrs[index] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		// Make a volume inside a go-routine.
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			err := disk.MakeVol(bucket)
-			if err != nil {
-				if err != errVolumeExists {
-					logger.LogIf(ctx, err)
+	for index := range storageDisks {
+		index := index
+		g.Go(func() error {
+			if storageDisks[index] != nil {
+				if err := storageDisks[index].MakeVol(bucket); err != nil {
+					if err != errVolumeExists {
+						logger.LogIf(ctx, err)
+					}
+					return err
 				}
-				dErrs[index] = err
+				return nil
 			}
-		}(index, disk)
+			return errDiskNotFound
+		}, index)
 	}
 
-	// Wait for all make vol to finish.
-	wg.Wait()
-
-	writeQuorum := len(xl.getDisks())/2 + 1
-	err := reduceWriteQuorumErrs(ctx, dErrs, bucketOpIgnoredErrs, writeQuorum)
+	writeQuorum := len(storageDisks)/2 + 1
+	err := reduceWriteQuorumErrs(ctx, g.Wait(), bucketOpIgnoredErrs, writeQuorum)
 	if err == errXLWriteQuorum {
 		// Purge successfully created buckets if we don't have writeQuorum.
-		undoMakeBucket(xl.getDisks(), bucket)
+		undoMakeBucket(storageDisks, bucket)
 	}
 	return toObjectErr(err, bucket)
 }
 
-func (xl xlObjects) undoDeleteBucket(bucket string) {
-	// Initialize sync waitgroup.
-	var wg sync.WaitGroup
+func undoDeleteBucket(storageDisks []StorageAPI, bucket string) {
+	g := errgroup.WithNErrs(len(storageDisks))
 	// Undo previous make bucket entry on all underlying storage disks.
-	for index, disk := range xl.getDisks() {
-		if disk == nil {
+	for index := range storageDisks {
+		if storageDisks[index] == nil {
 			continue
 		}
-		wg.Add(1)
-		// Delete a bucket inside a go-routine.
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			_ = disk.MakeVol(bucket)
-		}(index, disk)
+		index := index
+		g.Go(func() error {
+			_ = storageDisks[index].MakeVol(bucket)
+			return nil
+		}, index)
 	}
 
 	// Wait for all make vol to finish.
-	wg.Wait()
+	g.Wait()
 }
 
 // undo make bucket operation upon quorum failure.
 func undoMakeBucket(storageDisks []StorageAPI, bucket string) {
-	// Initialize sync waitgroup.
-	var wg sync.WaitGroup
+	g := errgroup.WithNErrs(len(storageDisks))
 	// Undo previous make bucket entry on all underlying storage disks.
-	for index, disk := range storageDisks {
-		if disk == nil {
+	for index := range storageDisks {
+		if storageDisks[index] == nil {
 			continue
 		}
-		wg.Add(1)
-		// Delete a bucket inside a go-routine.
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			_ = disk.DeleteVol(bucket)
-		}(index, disk)
+		index := index
+		g.Go(func() error {
+			_ = storageDisks[index].DeleteVol(bucket)
+			return nil
+		}, index)
 	}
 
 	// Wait for all make vol to finish.
-	wg.Wait()
+	g.Wait()
 }
 
 // getBucketInfo - returns the BucketInfo from one of the load balanced disks.
@@ -245,42 +233,34 @@ func (xl xlObjects) DeleteBucket(ctx context.Context, bucket string) error {
 	defer bucketLock.Unlock()
 
 	// Collect if all disks report volume not found.
-	var wg sync.WaitGroup
-	var dErrs = make([]error, len(xl.getDisks()))
-
-	// Remove a volume entry on all underlying storage disks.
 	storageDisks := xl.getDisks()
-	for index, disk := range storageDisks {
-		if disk == nil {
-			dErrs[index] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		// Delete volume inside a go-routine.
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			// Attempt to delete bucket.
-			err := disk.DeleteVol(bucket)
-			if err != nil {
-				dErrs[index] = err
-				return
-			}
 
-			// Cleanup all the previously incomplete multiparts.
-			err = cleanupDir(ctx, disk, minioMetaMultipartBucket, bucket)
-			if err != nil && err != errVolumeNotFound {
-				dErrs[index] = err
+	g := errgroup.WithNErrs(len(storageDisks))
+
+	for index := range storageDisks {
+		index := index
+		g.Go(func() error {
+			if storageDisks[index] != nil {
+				if err := storageDisks[index].DeleteVol(bucket); err != nil {
+					return err
+				}
+				err := cleanupDir(ctx, storageDisks[index], minioMetaMultipartBucket, bucket)
+				if err != nil && err != errVolumeNotFound {
+					return err
+				}
+				return nil
 			}
-		}(index, disk)
+			return errDiskNotFound
+		}, index)
 	}
 
 	// Wait for all the delete vols to finish.
-	wg.Wait()
+	dErrs := g.Wait()
 
-	writeQuorum := len(xl.getDisks())/2 + 1
+	writeQuorum := len(storageDisks)/2 + 1
 	err := reduceWriteQuorumErrs(ctx, dErrs, bucketOpIgnoredErrs, writeQuorum)
 	if err == errXLWriteQuorum {
-		xl.undoDeleteBucket(bucket)
+		undoDeleteBucket(storageDisks, bucket)
 	}
 	if err != nil {
 		return toObjectErr(err, bucket)

cmd/xl-v1-common.go

@@ -19,7 +19,8 @@ package cmd
 import (
 	"context"
 	"path"
-	"sync"
+
+	"github.com/minio/minio/pkg/sync/errgroup"
 )
 
 // getLoadBalancedDisks - fetches load balanced (sufficiently randomized) disk slice.
@@ -53,35 +54,33 @@ func (xl xlObjects) parentDirIsObject(ctx context.Context, bucket, parent string
 // isObject - returns `true` if the prefix is an object i.e if
 // `xl.json` exists at the leaf, false otherwise.
 func (xl xlObjects) isObject(bucket, prefix string) (ok bool) {
-	var errs = make([]error, len(xl.getDisks()))
-	var wg sync.WaitGroup
-	for index, disk := range xl.getDisks() {
+	storageDisks := xl.getDisks()
+
+	g := errgroup.WithNErrs(len(storageDisks))
+
+	for index, disk := range storageDisks {
 		if disk == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
+		index := index
+		g.Go(func() error {
 			// Check if 'prefix' is an object on this 'disk', else continue the check the next disk
-			fi, err := disk.StatFile(bucket, path.Join(prefix, xlMetaJSONFile))
+			fi, err := storageDisks[index].StatFile(bucket, pathJoin(prefix, xlMetaJSONFile))
 			if err != nil {
-				errs[index] = err
-				return
+				return err
 			}
 			if fi.Size == 0 {
-				errs[index] = errCorruptedFormat
-				return
+				return errCorruptedFormat
 			}
-		}(index, disk)
+			return nil
+		}, index)
 	}
 
-	wg.Wait()
-
 	// NOTE: Observe we are not trying to read `xl.json` and figure out the actual
 	// quorum intentionally, but rely on the default case scenario. Actual quorum
 	// verification will happen by top layer by using getObjectInfo() and will be
 	// ignored if necessary.
-	readQuorum := len(xl.getDisks()) / 2
+	readQuorum := len(storageDisks) / 2
 
-	return reduceReadQuorumErrs(context.Background(), errs, objectOpIgnoredErrs, readQuorum) == nil
+	return reduceReadQuorumErrs(context.Background(), g.Wait(), objectOpIgnoredErrs, readQuorum) == nil
 }

cmd/xl-v1-healing.go

@@ -20,11 +20,11 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"sync"
 	"time"
 
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/madmin"
+	"github.com/minio/minio/pkg/sync/errgroup"
 )
 
 func (xl xlObjects) ReloadFormat(ctx context.Context, dryRun bool) error {
@@ -57,40 +57,31 @@ func healBucket(ctx context.Context, storageDisks []StorageAPI, bucket string, w
 	dryRun bool) (res madmin.HealResultItem, err error) {
 
 	// Initialize sync waitgroup.
-	var wg sync.WaitGroup
-
-	// Initialize list of errors.
-	var dErrs = make([]error, len(storageDisks))
+	g := errgroup.WithNErrs(len(storageDisks))
 
 	// Disk states slices
 	beforeState := make([]string, len(storageDisks))
 	afterState := make([]string, len(storageDisks))
 
 	// Make a volume entry on all underlying storage disks.
-	for index, disk := range storageDisks {
-		if disk == nil {
-			dErrs[index] = errDiskNotFound
-			beforeState[index] = madmin.DriveStateOffline
-			afterState[index] = madmin.DriveStateOffline
-			continue
-		}
-		wg.Add(1)
-
-		// Make a volume inside a go-routine.
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			if _, serr := disk.StatVol(bucket); serr != nil {
+	for index := range storageDisks {
+		index := index
+		g.Go(func() error {
+			if storageDisks[index] == nil {
+				beforeState[index] = madmin.DriveStateOffline
+				afterState[index] = madmin.DriveStateOffline
+				return errDiskNotFound
+			}
+			if _, serr := storageDisks[index].StatVol(bucket); serr != nil {
 				if serr == errDiskNotFound {
 					beforeState[index] = madmin.DriveStateOffline
 					afterState[index] = madmin.DriveStateOffline
-					dErrs[index] = serr
-					return
+					return serr
 				}
 				if serr != errVolumeNotFound {
 					beforeState[index] = madmin.DriveStateCorrupt
 					afterState[index] = madmin.DriveStateCorrupt
-					dErrs[index] = serr
-					return
+					return serr
 				}
 
 				beforeState[index] = madmin.DriveStateMissing
@@ -98,23 +89,22 @@ func healBucket(ctx context.Context, storageDisks []StorageAPI, bucket string, w
 
 				// mutate only if not a dry-run
 				if dryRun {
-					return
+					return nil
 				}
 
-				makeErr := disk.MakeVol(bucket)
-				dErrs[index] = makeErr
+				makeErr := storageDisks[index].MakeVol(bucket)
 				if makeErr == nil {
 					afterState[index] = madmin.DriveStateOk
 				}
-				return
+				return makeErr
 			}
 			beforeState[index] = madmin.DriveStateOk
 			afterState[index] = madmin.DriveStateOk
-		}(index, disk)
+			return nil
+		}, index)
 	}
 
-	// Wait for all make vol to finish.
-	wg.Wait()
+	errs := g.Wait()
 
 	// Initialize heal result info
 	res = madmin.HealResultItem{
@@ -122,13 +112,13 @@ func healBucket(ctx context.Context, storageDisks []StorageAPI, bucket string, w
 		Bucket:    bucket,
 		DiskCount: len(storageDisks),
 	}
-	for i, before := range beforeState {
+	for i := range beforeState {
 		if storageDisks[i] != nil {
 			drive := storageDisks[i].String()
 			res.Before.Drives = append(res.Before.Drives, madmin.HealDriveInfo{
 				UUID:     "",
 				Endpoint: drive,
-				State:    before,
+				State:    beforeState[i],
 			})
 			res.After.Drives = append(res.After.Drives, madmin.HealDriveInfo{
 				UUID:     "",
@@ -138,7 +128,7 @@ func healBucket(ctx context.Context, storageDisks []StorageAPI, bucket string, w
 		}
 	}
 
-	reducedErr := reduceWriteQuorumErrs(ctx, dErrs, bucketOpIgnoredErrs, writeQuorum)
+	reducedErr := reduceWriteQuorumErrs(ctx, errs, bucketOpIgnoredErrs, writeQuorum)
 	if reducedErr == errXLWriteQuorum {
 		// Purge successfully created buckets if we don't have writeQuorum.
 		undoMakeBucket(storageDisks, bucket)
@@ -597,29 +587,25 @@ func defaultHealResult(latestXLMeta xlMetaV1, storageDisks []StorageAPI, errs []
 
 // Stat all directories.
 func statAllDirs(ctx context.Context, storageDisks []StorageAPI, bucket, prefix string) []error {
-	var errs = make([]error, len(storageDisks))
-	var wg sync.WaitGroup
+	g := errgroup.WithNErrs(len(storageDisks))
 	for index, disk := range storageDisks {
 		if disk == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			entries, err := disk.ListDir(bucket, prefix, 1, "")
+		index := index
+		g.Go(func() error {
+			entries, err := storageDisks[index].ListDir(bucket, prefix, 1, "")
 			if err != nil {
-				errs[index] = err
-				return
+				return err
 			}
 			if len(entries) > 0 {
-				errs[index] = errVolumeNotEmpty
-				return
+				return errVolumeNotEmpty
 			}
-		}(index, disk)
+			return nil
+		}, index)
 	}
 
-	wg.Wait()
-	return errs
+	return g.Wait()
 }
 
 // ObjectDir is considered dangling/corrupted if any only

cmd/xl-v1-metadata.go

@@ -24,11 +24,11 @@ import (
 	"net/http"
 	"path"
 	"sort"
-	"sync"
 	"time"
 
 	xhttp "github.com/minio/minio/cmd/http"
 	"github.com/minio/minio/cmd/logger"
+	"github.com/minio/minio/pkg/sync/errgroup"
 	"github.com/minio/sha256-simd"
 )
 
@@ -452,31 +452,23 @@ func renameXLMetadata(ctx context.Context, disks []StorageAPI, srcBucket, srcEnt
 
 // writeUniqueXLMetadata - writes unique `xl.json` content for each disk in order.
 func writeUniqueXLMetadata(ctx context.Context, disks []StorageAPI, bucket, prefix string, xlMetas []xlMetaV1, quorum int) ([]StorageAPI, error) {
-	var wg sync.WaitGroup
-	var mErrs = make([]error, len(disks))
+	g := errgroup.WithNErrs(len(disks))
 
 	// Start writing `xl.json` to all disks in parallel.
-	for index, disk := range disks {
-		if disk == nil {
-			mErrs[index] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-
-		// Pick one xlMeta for a disk at index.
-		xlMetas[index].Erasure.Index = index + 1
-
-		// Write `xl.json` in a routine.
-		go func(index int, disk StorageAPI, xlMeta xlMetaV1) {
-			defer wg.Done()
-
-			// Write unique `xl.json` for a disk at index.
-			mErrs[index] = writeXLMetadata(ctx, disk, bucket, prefix, xlMeta)
-		}(index, disk, xlMetas[index])
+	for index := range disks {
+		index := index
+		g.Go(func() error {
+			if disks[index] == nil {
+				return errDiskNotFound
+			}
+			// Pick one xlMeta for a disk at index.
+			xlMetas[index].Erasure.Index = index + 1
+			return writeXLMetadata(ctx, disks[index], bucket, prefix, xlMetas[index])
+		}, index)
 	}
 
 	// Wait for all the routines.
-	wg.Wait()
+	mErrs := g.Wait()
 
 	err := reduceWriteQuorumErrs(ctx, mErrs, objectOpIgnoredErrs, quorum)
 	return evalDisks(disks, mErrs), err

cmd/xl-v1-multipart.go

@@ -24,12 +24,12 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 
 	xhttp "github.com/minio/minio/cmd/http"
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/mimedb"
+	"github.com/minio/minio/pkg/sync/errgroup"
 )
 
 func (xl xlObjects) getUploadIDDir(bucket, object, uploadID string) string {
@@ -57,21 +57,23 @@ func (xl xlObjects) checkUploadIDExists(ctx context.Context, bucket, object, upl
 // Removes part given by partName belonging to a mulitpart upload from minioMetaBucket
 func (xl xlObjects) removeObjectPart(bucket, object, uploadID, partName string) {
 	curpartPath := path.Join(bucket, object, uploadID, partName)
-	var wg sync.WaitGroup
-	for i, disk := range xl.getDisks() {
+	storageDisks := xl.getDisks()
+
+	g := errgroup.WithNErrs(len(storageDisks))
+	for index, disk := range storageDisks {
 		if disk == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
+		index := index
+		g.Go(func() error {
 			// Ignoring failure to remove parts that weren't present in CompleteMultipartUpload
 			// requests. xl.json is the authoritative source of truth on which parts constitute
 			// the object. The presence of parts that don't belong in the object doesn't affect correctness.
-			_ = disk.DeleteFile(minioMetaMultipartBucket, curpartPath)
-		}(i, disk)
+			_ = storageDisks[index].DeleteFile(minioMetaMultipartBucket, curpartPath)
+			return nil
+		}, index)
 	}
-	wg.Wait()
+	g.Wait()
 }
 
 // statPart - returns fileInfo structure for a successful stat on part file.
@@ -104,31 +106,29 @@ func (xl xlObjects) statPart(ctx context.Context, bucket, object, uploadID, part
 
 // commitXLMetadata - commit `xl.json` from source prefix to destination prefix in the given slice of disks.
 func commitXLMetadata(ctx context.Context, disks []StorageAPI, srcBucket, srcPrefix, dstBucket, dstPrefix string, quorum int) ([]StorageAPI, error) {
-	var wg sync.WaitGroup
-	var mErrs = make([]error, len(disks))
-
 	srcJSONFile := path.Join(srcPrefix, xlMetaJSONFile)
 	dstJSONFile := path.Join(dstPrefix, xlMetaJSONFile)
 
+	g := errgroup.WithNErrs(len(disks))
+
 	// Rename `xl.json` to all disks in parallel.
-	for index, disk := range disks {
-		if disk == nil {
-			mErrs[index] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		// Rename `xl.json` in a routine.
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
+	for index := range disks {
+		index := index
+		g.Go(func() error {
+			if disks[index] == nil {
+				return errDiskNotFound
+			}
+
 			// Delete any dangling directories.
-			defer disk.DeleteFile(srcBucket, srcPrefix)
+			defer disks[index].DeleteFile(srcBucket, srcPrefix)
 
 			// Renames `xl.json` from source prefix to destination prefix.
-			mErrs[index] = disk.RenameFile(srcBucket, srcJSONFile, dstBucket, dstJSONFile)
-		}(index, disk)
+			return disks[index].RenameFile(srcBucket, srcJSONFile, dstBucket, dstJSONFile)
+		}, index)
 	}
+
 	// Wait for all the routines.
-	wg.Wait()
+	mErrs := g.Wait()
 
 	err := reduceWriteQuorumErrs(ctx, mErrs, objectOpIgnoredErrs, quorum)
 	return evalDisks(disks, mErrs), err

cmd/xl-v1-object.go

@@ -22,11 +22,11 @@ import (
 	"io"
 	"net/http"
 	"path"
-	"sync"
 
 	xhttp "github.com/minio/minio/cmd/http"
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/mimedb"
+	"github.com/minio/minio/pkg/sync/errgroup"
 )
 
 // list all errors which can be ignored in object operations.
@@ -34,25 +34,26 @@ var objectOpIgnoredErrs = append(baseIgnoredErrs, errDiskAccessDenied)
 
 // putObjectDir hints the bottom layer to create a new directory.
 func (xl xlObjects) putObjectDir(ctx context.Context, bucket, object string, writeQuorum int) error {
-	var wg sync.WaitGroup
+	storageDisks := xl.getDisks()
+
+	g := errgroup.WithNErrs(len(storageDisks))
 
-	errs := make([]error, len(xl.getDisks()))
 	// Prepare object creation in all disks
-	for index, disk := range xl.getDisks() {
-		if disk == nil {
+	for index := range storageDisks {
+		if storageDisks[index] == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			if err := disk.MakeVol(pathJoin(bucket, object)); err != nil && err != errVolumeExists {
-				errs[index] = err
+		index := index
+		g.Go(func() error {
+			err := storageDisks[index].MakeVol(pathJoin(bucket, object))
+			if err != nil && err != errVolumeExists {
+				return err
 			}
-		}(index, disk)
+			return nil
+		}, index)
 	}
-	wg.Wait()
 
-	return reduceWriteQuorumErrs(ctx, errs, objectOpIgnoredErrs, writeQuorum)
+	return reduceWriteQuorumErrs(ctx, g.Wait(), objectOpIgnoredErrs, writeQuorum)
 }
 
 /// Object Operations
@@ -335,36 +336,34 @@ func (xl xlObjects) getObject(ctx context.Context, bucket, object string, startO
 }
 
 // getObjectInfoDir - This getObjectInfo is specific to object directory lookup.
-func (xl xlObjects) getObjectInfoDir(ctx context.Context, bucket, object string) (oi ObjectInfo, err error) {
-	var wg sync.WaitGroup
+func (xl xlObjects) getObjectInfoDir(ctx context.Context, bucket, object string) (ObjectInfo, error) {
+	storageDisks := xl.getDisks()
+
+	g := errgroup.WithNErrs(len(storageDisks))
 
-	errs := make([]error, len(xl.getDisks()))
 	// Prepare object creation in a all disks
-	for index, disk := range xl.getDisks() {
+	for index, disk := range storageDisks {
 		if disk == nil {
 			continue
 		}
-		wg.Add(1)
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
+		index := index
+		g.Go(func() error {
 			// Check if 'prefix' is an object on this 'disk'.
-			entries, err := disk.ListDir(bucket, object, 1, "")
+			entries, err := storageDisks[index].ListDir(bucket, object, 1, "")
 			if err != nil {
-				errs[index] = err
-				return
+				return err
 			}
 			if len(entries) > 0 {
 				// Not a directory if not empty.
-				errs[index] = errFileNotFound
-				return
+				return errFileNotFound
 			}
-		}(index, disk)
+			return nil
+		}, index)
 	}
 
-	wg.Wait()
-
-	readQuorum := len(xl.getDisks()) / 2
-	return dirObjectInfo(bucket, object, 0, map[string]string{}), reduceReadQuorumErrs(ctx, errs, objectOpIgnoredErrs, readQuorum)
+	readQuorum := len(storageDisks) / 2
+	err := reduceReadQuorumErrs(ctx, g.Wait(), objectOpIgnoredErrs, readQuorum)
+	return dirObjectInfo(bucket, object, 0, map[string]string{}), err
 }
 
 // GetObjectInfo - reads object metadata and replies back ObjectInfo.
@@ -424,7 +423,6 @@ func (xl xlObjects) getObjectInfo(ctx context.Context, bucket, object string) (o
 }
 
 func undoRename(disks []StorageAPI, srcBucket, srcEntry, dstBucket, dstEntry string, isDir bool, errs []error) {
-	var wg sync.WaitGroup
 	// Undo rename object on disks where RenameFile succeeded.
 
 	// If srcEntry/dstEntry are objects then add a trailing slash to copy
@@ -433,56 +431,51 @@ func undoRename(disks []StorageAPI, srcBucket, srcEntry, dstBucket, dstEntry str
 		srcEntry = retainSlash(srcEntry)
 		dstEntry = retainSlash(dstEntry)
 	}
+	g := errgroup.WithNErrs(len(disks))
 	for index, disk := range disks {
 		if disk == nil {
 			continue
 		}
-		// Undo rename object in parallel.
-		wg.Add(1)
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			if errs[index] != nil {
-				return
+		index := index
+		g.Go(func() error {
+			if errs[index] == nil {
+				_ = disks[index].RenameFile(dstBucket, dstEntry, srcBucket, srcEntry)
 			}
-			_ = disk.RenameFile(dstBucket, dstEntry, srcBucket, srcEntry)
-		}(index, disk)
+			return nil
+		}, index)
 	}
-	wg.Wait()
+	g.Wait()
 }
 
 // rename - common function that renamePart and renameObject use to rename
 // the respective underlying storage layer representations.
 func rename(ctx context.Context, disks []StorageAPI, srcBucket, srcEntry, dstBucket, dstEntry string, isDir bool, writeQuorum int, ignoredErr []error) ([]StorageAPI, error) {
-	// Initialize sync waitgroup.
-	var wg sync.WaitGroup
-
-	// Initialize list of errors.
-	var errs = make([]error, len(disks))
 
 	if isDir {
 		dstEntry = retainSlash(dstEntry)
 		srcEntry = retainSlash(srcEntry)
 	}
 
+	g := errgroup.WithNErrs(len(disks))
+
 	// Rename file on all underlying storage disks.
-	for index, disk := range disks {
-		if disk == nil {
-			errs[index] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			if err := disk.RenameFile(srcBucket, srcEntry, dstBucket, dstEntry); err != nil {
+	for index := range disks {
+		index := index
+		g.Go(func() error {
+			if disks[index] == nil {
+				return errDiskNotFound
+			}
+			if err := disks[index].RenameFile(srcBucket, srcEntry, dstBucket, dstEntry); err != nil {
 				if !IsErrIgnored(err, ignoredErr...) {
-					errs[index] = err
+					return err
 				}
 			}
-		}(index, disk)
+			return nil
+		}, index)
 	}
 
 	// Wait for all renames to finish.
-	wg.Wait()
+	errs := g.Wait()
 
 	// We can safely allow RenameFile errors up to len(xl.getDisks()) - writeQuorum
 	// otherwise return failure. Cleanup successful renames.
@@ -744,39 +737,31 @@ func (xl xlObjects) deleteObject(ctx context.Context, bucket, object string, wri
 		}
 	}
 
-	// Initialize sync waitgroup.
-	var wg sync.WaitGroup
-
-	// Initialize list of errors.
-	var dErrs = make([]error, len(disks))
+	g := errgroup.WithNErrs(len(disks))
 
-	for index, disk := range disks {
-		if disk == nil {
-			dErrs[index] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		go func(index int, disk StorageAPI, isDir bool) {
-			defer wg.Done()
-			var e error
+	for index := range disks {
+		index := index
+		g.Go(func() error {
+			if disks[index] == nil {
+				return errDiskNotFound
+			}
+			var err error
 			if isDir {
 				// DeleteFile() simply tries to remove a directory
 				// and will succeed only if that directory is empty.
-				e = disk.DeleteFile(minioMetaTmpBucket, tmpObj)
+				err = disks[index].DeleteFile(minioMetaTmpBucket, tmpObj)
 			} else {
-				e = cleanupDir(ctx, disk, minioMetaTmpBucket, tmpObj)
+				err = cleanupDir(ctx, disks[index], minioMetaTmpBucket, tmpObj)
 			}
-			if e != nil && e != errVolumeNotFound {
-				dErrs[index] = e
+			if err != nil && err != errVolumeNotFound {
+				return err
 			}
-		}(index, disk, isDir)
+			return nil
+		}, index)
 	}
 
-	// Wait for all routines to finish.
-	wg.Wait()
-
 	// return errors if any during deletion
-	return reduceWriteQuorumErrs(ctx, dErrs, objectOpIgnoredErrs, writeQuorum)
+	return reduceWriteQuorumErrs(ctx, g.Wait(), objectOpIgnoredErrs, writeQuorum)
 }
 
 // deleteObject - wrapper for delete object, deletes an object from

cmd/xl-v1-utils.go

@@ -21,10 +21,10 @@ import (
 	"errors"
 	"hash/crc32"
 	"path"
-	"sync"
 
 	jsoniter "github.com/json-iterator/go"
 	"github.com/minio/minio/cmd/logger"
+	"github.com/minio/minio/pkg/sync/errgroup"
 )
 
 // Returns number of errors that occurred the most (incl. nil) and the
@@ -180,28 +180,23 @@ func readXLMeta(ctx context.Context, disk StorageAPI, bucket string, object stri
 // Reads all `xl.json` metadata as a xlMetaV1 slice.
 // Returns error slice indicating the failed metadata reads.
 func readAllXLMetadata(ctx context.Context, disks []StorageAPI, bucket, object string) ([]xlMetaV1, []error) {
-	errs := make([]error, len(disks))
 	metadataArray := make([]xlMetaV1, len(disks))
-	var wg sync.WaitGroup
+
+	g := errgroup.WithNErrs(len(disks))
 	// Read `xl.json` parallelly across disks.
-	for index, disk := range disks {
-		if disk == nil {
-			errs[index] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		// Read `xl.json` in routine.
-		go func(index int, disk StorageAPI) {
-			defer wg.Done()
-			metadataArray[index], errs[index] = readXLMeta(ctx, disk, bucket, object)
-		}(index, disk)
+	for index := range disks {
+		index := index
+		g.Go(func() (err error) {
+			if disks[index] == nil {
+				return errDiskNotFound
+			}
+			metadataArray[index], err = readXLMeta(ctx, disks[index], bucket, object)
+			return err
+		}, index)
 	}
 
-	// Wait for all the routines to finish.
-	wg.Wait()
-
 	// Return all the metadata.
-	return metadataArray, errs
+	return metadataArray, g.Wait()
 }
 
 // Return shuffled partsMetadata depending on distribution.

cmd/xl-v1.go

@@ -19,10 +19,10 @@ package cmd
 import (
 	"context"
 	"sort"
-	"sync"
 
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/bpool"
+	"github.com/minio/minio/pkg/sync/errgroup"
 )
 
 // XL constants.
@@ -71,34 +71,31 @@ func (d byDiskTotal) Less(i, j int) bool {
 // getDisksInfo - fetch disks info across all other storage API.
 func getDisksInfo(disks []StorageAPI) (disksInfo []DiskInfo, onlineDisks int, offlineDisks int) {
 	disksInfo = make([]DiskInfo, len(disks))
-	errs := make([]error, len(disks))
-	var wg sync.WaitGroup
-	for i, storageDisk := range disks {
-		if storageDisk == nil {
-			// Storage disk is empty, perhaps ignored disk or not available.
-			errs[i] = errDiskNotFound
-			continue
-		}
-		wg.Add(1)
-		go func(id int, sDisk StorageAPI) {
-			defer wg.Done()
-			info, err := sDisk.DiskInfo()
+
+	g := errgroup.WithNErrs(len(disks))
+	for index := range disks {
+		index := index
+		g.Go(func() error {
+			if disks[index] == nil {
+				// Storage disk is empty, perhaps ignored disk or not available.
+				return errDiskNotFound
+			}
+			info, err := disks[index].DiskInfo()
 			if err != nil {
-				reqInfo := (&logger.ReqInfo{}).AppendTags("disk", sDisk.String())
-				ctx := logger.SetReqInfo(context.Background(), reqInfo)
-				logger.LogIf(ctx, err)
 				if IsErr(err, baseErrs...) {
-					errs[id] = err
-					return
+					return err
 				}
+				reqInfo := (&logger.ReqInfo{}).AppendTags("disk", disks[index].String())
+				ctx := logger.SetReqInfo(context.Background(), reqInfo)
+				logger.LogIf(ctx, err)
 			}
-			disksInfo[id] = info
-		}(i, storageDisk)
+			disksInfo[index] = info
+			return nil
+		}, index)
 	}
-	// Wait for the routines.
-	wg.Wait()
 
-	for _, err := range errs {
+	// Wait for the routines.
+	for _, err := range g.Wait() {
 		if err != nil {
 			offlineDisks++
 			continue