Begin implementing EC balancing parallelization support. (#6342)

* Begin implementing EC balancing parallelization support.

Impacts both `ec.encode` and `ec.balance`,

* Nit: improve type naming.

* Make the goroutine workgroup handler for `EcBalance()` a bit smarter/error-proof.

* Nit: unify naming for `ecBalancer` wait group methods with the rest of the module.

* Fix concurrency bug.

* Fix whitespace after Gitlab automerge.

* Delete stray TODO.

weed/shell/command_ec_balance.go

@@ -17,7 +17,6 @@ func (c *commandEcBalance) Name() string {
 	return "ec.balance"
 }
 
-// TODO: Update help string and move to command_ec_common.go once shard replica placement logic is enabled.
 func (c *commandEcBalance) Help() string {
 	return `balance all ec shards among all racks and volume servers
 
@@ -36,6 +35,7 @@ func (c *commandEcBalance) Do(args []string, commandEnv *CommandEnv, writer io.W
 	collection := balanceCommand.String("collection", "EACH_COLLECTION", "collection name, or \"EACH_COLLECTION\" for each collection")
 	dc := balanceCommand.String("dataCenter", "", "only apply the balancing for this dataCenter")
 	shardReplicaPlacement := balanceCommand.String("shardReplicaPlacement", "", "replica placement for EC shards, or master default if empty")
+	parallelize := balanceCommand.Bool("parallelize", true, "parallelize operations whenever possible")
 	applyBalancing := balanceCommand.Bool("force", false, "apply the balancing plan")
 	if err = balanceCommand.Parse(args); err != nil {
 		return nil
@@ -62,5 +62,5 @@ func (c *commandEcBalance) Do(args []string, commandEnv *CommandEnv, writer io.W
 		return err
 	}
 
-	return EcBalance(commandEnv, collections, *dc, rp, *applyBalancing)
+	return EcBalance(commandEnv, collections, *dc, rp, *parallelize, *applyBalancing)
 }

weed/shell/command_ec_common.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"math/rand/v2"
 	"sort"
+	"sync"
 	"time"
 
 	"github.com/seaweedfs/seaweedfs/weed/glog"
@@ -556,6 +557,48 @@ type ecBalancer struct {
 	ecNodes          []*EcNode
 	replicaPlacement *super_block.ReplicaPlacement
 	applyBalancing   bool
+	parallelize      bool
+
+	wg *sync.WaitGroup
+	// TODO: Maybe accumulate all errors instead of just the last one.
+	wgError error
+}
+
+type ecBalancerTask func() error
+
+func (ecb *ecBalancer) wgInit() {
+	if ecb.wg == nil {
+		ecb.wg = &sync.WaitGroup{}
+		ecb.wgError = nil
+	}
+}
+
+func (ecb *ecBalancer) wgAdd(f ecBalancerTask) {
+	if ecb.wg == nil || !ecb.parallelize {
+		if err := f(); err != nil {
+			ecb.wgError = err
+		}
+		return
+	}
+
+	ecb.wg.Add(1)
+	go func() {
+		if err := f(); err != nil {
+			ecb.wgError = err
+		}
+		ecb.wg.Done()
+	}()
+}
+
+func (ecb *ecBalancer) wgWait() error {
+	if ecb.wg != nil {
+		ecb.wg.Wait()
+	}
+	err := ecb.wgError
+	ecb.wg = nil
+	ecb.wgError = nil
+
+	return err
 }
 
 func (ecb *ecBalancer) racks() map[RackId]*EcRack {
@@ -592,15 +635,15 @@ func (ecb *ecBalancer) balanceEcVolumes(collection string) error {
 }
 
 func (ecb *ecBalancer) deleteDuplicatedEcShards(collection string) error {
-	// vid => []ecNode
 	vidLocations := ecb.collectVolumeIdToEcNodes(collection)
-	// deduplicate ec shards
+
+	ecb.wgInit()
 	for vid, locations := range vidLocations {
-		if err := ecb.doDeduplicateEcShards(collection, vid, locations); err != nil {
+		ecb.wgAdd(func() error {
-			return err
+			return ecb.doDeduplicateEcShards(collection, vid, locations)
+		})
 	}
-	}
+	return ecb.wgWait()
-	return nil
 }
 
 func (ecb *ecBalancer) doDeduplicateEcShards(collection string, vid needle.VolumeId, locations []*EcNode) error {
@@ -636,6 +679,7 @@ func (ecb *ecBalancer) doDeduplicateEcShards(collection string, vid needle.Volum
 	return nil
 }
 
+// TODO: enable parallelization
 func (ecb *ecBalancer) balanceEcShardsAcrossRacks(collection string) error {
 	// collect vid => []ecNode, since previous steps can change the locations
 	vidLocations := ecb.collectVolumeIdToEcNodes(collection)
@@ -741,6 +785,7 @@ func (ecb *ecBalancer) pickRackToBalanceShardsInto(rackToEcNodes map[RackId]*EcR
 	return targets[rand.IntN(len(targets))], nil
 }
 
+// TODO: enable parallelization
 func (ecb *ecBalancer) balanceEcShardsWithinRacks(collection string) error {
 	// collect vid => []ecNode, since previous steps can change the locations
 	vidLocations := ecb.collectVolumeIdToEcNodes(collection)
@@ -809,6 +854,7 @@ func (ecb *ecBalancer) balanceEcRacks() error {
 	return nil
 }
 
+// TODO: enable parallelization
 func (ecb *ecBalancer) doBalanceEcRack(ecRack *EcRack) error {
 	if len(ecRack.ecNodes) <= 1 {
 		return nil
@@ -1001,7 +1047,7 @@ func (ecb *ecBalancer) collectVolumeIdToEcNodes(collection string) map[needle.Vo
 	return vidLocations
 }
 
-func EcBalance(commandEnv *CommandEnv, collections []string, dc string, ecReplicaPlacement *super_block.ReplicaPlacement, applyBalancing bool) (err error) {
+func EcBalance(commandEnv *CommandEnv, collections []string, dc string, ecReplicaPlacement *super_block.ReplicaPlacement, parallelize bool, applyBalancing bool) (err error) {
 	if len(collections) == 0 {
 		return fmt.Errorf("no collections to balance")
 	}
@@ -1020,6 +1066,7 @@ func EcBalance(commandEnv *CommandEnv, collections []string, dc string, ecReplic
 		ecNodes:          allEcNodes,
 		replicaPlacement: ecReplicaPlacement,
 		applyBalancing:   applyBalancing,
+		parallelize:      parallelize,
 	}
 
 	for _, c := range collections {

weed/shell/command_ec_encode.go

@@ -65,8 +65,7 @@ func (c *commandEcEncode) Do(args []string, commandEnv *CommandEnv, writer io.Wr
 	collection := encodeCommand.String("collection", "", "the collection name")
 	fullPercentage := encodeCommand.Float64("fullPercent", 95, "the volume reaches the percentage of max volume size")
 	quietPeriod := encodeCommand.Duration("quietFor", time.Hour, "select volumes without no writes for this period")
-	// TODO: Add concurrency support to EcBalance and reenable this switch?
+	parallelize := encodeCommand.Bool("parallelize", true, "parallelize operations whenever possible")
-	//parallelCopy := encodeCommand.Bool("parallelCopy", true, "copy shards in parallel")
 	forceChanges := encodeCommand.Bool("force", false, "force the encoding even if the cluster has less than recommended 4 nodes")
 	shardReplicaPlacement := encodeCommand.String("shardReplicaPlacement", "", "replica placement for EC shards, or master default if empty")
 	applyBalancing := encodeCommand.Bool("rebalance", false, "re-balance EC shards after creation")
@@ -125,7 +124,7 @@ func (c *commandEcEncode) Do(args []string, commandEnv *CommandEnv, writer io.Wr
 		}
 	}
 	// ...then re-balance ec shards.
-	if err := EcBalance(commandEnv, collections, "", rp, *applyBalancing); err != nil {
+	if err := EcBalance(commandEnv, collections, "", rp, *parallelize, *applyBalancing); err != nil {
 		return fmt.Errorf("re-balance ec shards for collection(s) %v: %v", collections, err)
 	}