feat(options): add NumGoroutines option for default Stream.numGo (#1656)

options.go

@@ -48,6 +48,8 @@ type Options struct {
 	Logger            Logger
 	Compression       options.CompressionType
 	InMemory          bool
+	// Sets the Stream.numGo field
+	NumGoroutines int
 
 	// Fine tuning options.
 
@@ -125,6 +127,7 @@ func DefaultOptions(path string) Options {
 		TableSizeMultiplier: 2,
 		LevelSizeMultiplier: 10,
 		MaxLevels:           7,
+		NumGoroutines:       8,
 
 		NumCompactors:           4, // Run at least 2 compactors. Zero-th compactor prioritizes L0.
 		NumLevelZeroTables:      5,
@@ -252,6 +255,14 @@ func (opt Options) WithNumVersionsToKeep(val int) Options {
 	return opt
 }
 
+// WithNumGoroutines sets the number of goroutines to be used in Stream.
+//
+// The default value of NumGoroutines is 8.
+func (opt Options) WithNumGoroutines(val int) Options {
+	opt.NumGoroutines = val
+	return opt
+}
+
 // WithReadOnly returns a new Options value with ReadOnly set to the given value.
 //
 // When ReadOnly is true the DB will be opened on read-only mode.

stream.go

@@ -446,7 +446,7 @@ func (st *Stream) Orchestrate(ctx context.Context) error {
 func (db *DB) newStream() *Stream {
 	return &Stream{
 		db:        db,
-		NumGo:     8,
+		NumGo:     db.opt.NumGoroutines,
 		LogPrefix: "Badger.Stream",
 	}
 }