From 38eea9b4a7cf8276afb23d5caa8751da5251cc84 Mon Sep 17 00:00:00 2001
From: Jason Aten <jason.aten@molecula.com>
Date: Mon, 27 Jul 2020 20:25:43 -0400
Subject: [PATCH 1/2] reparallelize view.go openFragmentsInTx()

---
 view.go | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/view.go b/view.go
index 106ae2b42..682b3fb00 100644
--- a/view.go
+++ b/view.go
@@ -171,17 +171,38 @@ func (v *view) openFragmentsInTx() error {
 	if err != nil {
 		return errors.Wrap(err, "SliceOfShards")
 	}
+
+	eg, ctx := errgroup.WithContext(context.Background())
+	var mu sync.Mutex
+
+shardLoop:
 	for _, shard := range shards {
-		frag := v.newFragment(v.fragmentPath(shard), shard)
-		if err := frag.Open(); err != nil {
-			return fmt.Errorf("open fragment: shard=%d, err=%s", frag.shard, err)
+		select {
+		case <-ctx.Done():
+			break shardLoop
+		default:
+
+			workQueue <- struct{}{}
+			v.holder.Logger.Debugf("open index/field/view/fragment: %s/%s/%s/%d", v.index, v.field, v.name, shard)
+			eg.Go(func() error {
+				defer func() {
+					<-workQueue
+				}()
+				frag := v.newFragment(v.fragmentPath(shard), shard)
+				if err := frag.Open(); err != nil {
+					return fmt.Errorf("open fragment: shard=%d, err=%s", frag.shard, err)
+				}
+				frag.RowAttrStore = v.rowAttrStore
+				v.holder.Logger.Debugf("add index/field/view/fragment to view.fragments: %s/%s/%s/%d", v.index, v.field, v.name, shard)
+				mu.Lock()
+				v.fragments[frag.shard] = frag
+				v.addKnownShard(frag.shard)
+				mu.Unlock()
+				return nil
+			})
 		}
-		frag.RowAttrStore = v.rowAttrStore
-		v.holder.Logger.Debugf("add index/field/view/fragment to view.fragments: %s/%s/%s/%d", v.index, v.field, v.name, shard)
-		v.fragments[frag.shard] = frag
-		v.addKnownShard(frag.shard)
 	}
-	return nil
+	return eg.Wait()
 }
 
 // close closes the view and its fragments.

From 71eccd121decefb884d08e87be042375102f4139 Mon Sep 17 00:00:00 2001
From: "Jason E. Aten" <jason.aten@molecula.com>
Date: Tue, 28 Jul 2020 07:50:22 -0400
Subject: [PATCH 2/2] fix race in view.openFragmentsInTx

---
 view.go | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/view.go b/view.go
index 682b3fb00..da61f1837 100644
--- a/view.go
+++ b/view.go
@@ -175,19 +175,32 @@ func (v *view) openFragmentsInTx() error {
 	eg, ctx := errgroup.WithContext(context.Background())
 	var mu sync.Mutex
 
+	shardCh := make(chan uint64, len(shards))
+	for i := range shards {
+		shardCh <- shards[i]
+	}
+
 shardLoop:
-	for _, shard := range shards {
+	for range shards {
 		select {
 		case <-ctx.Done():
 			break shardLoop
 		default:
 
 			workQueue <- struct{}{}
-			v.holder.Logger.Debugf("open index/field/view/fragment: %s/%s/%s/%d", v.index, v.field, v.name, shard)
 			eg.Go(func() error {
 				defer func() {
 					<-workQueue
 				}()
+
+				var shard uint64
+				select {
+				case shard = <-shardCh:
+				default:
+					return nil // no more work
+				}
+				v.holder.Logger.Debugf("open index/field/view/fragment: %s/%s/%s/%d", v.index, v.field, v.name, shard)
+
 				frag := v.newFragment(v.fragmentPath(shard), shard)
 				if err := frag.Open(); err != nil {
 					return fmt.Errorf("open fragment: shard=%d, err=%s", frag.shard, err)