Set default max-parallel-downloads in new config

cfg/config.go

@@ -20,6 +20,7 @@ import (
 	"net/url"
 	"time"
 
+	"github.com/googlecloudplatform/gcsfuse/v2/internal/config"
 	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
 )
@@ -560,7 +561,7 @@ func BindFlags(flagSet *pflag.FlagSet) error {
 		return err
 	}
 
-	flagSet.IntP("max-parallel-downloads", "", -1, "Sets an uber limit of number of concurrent file download requests that are made across all files.")
+	flagSet.IntP("max-parallel-downloads", "", config.DefaultMaxParallelDownloads(), "Sets an uber limit of number of concurrent file download requests that are made across all files.")
 
 	err = viper.BindPFlag("file-cache.max-parallel-downloads", flagSet.Lookup("max-parallel-downloads"))
 	if err != nil {

cmd/root_test.go

@@ -48,6 +48,20 @@ func TestValidConfig(t *testing.T) {
 	assert.Nil(t, cmd.Execute())
 }
 
+func TestDefaultMaxParallelDownloads(t *testing.T) {
+	var actual cfg.Config
+	cmd, err := NewRootCmd(func(c cfg.Config) error {
+		actual = c
+		return nil
+	})
+	require.Nil(t, err)
+	cmd.SetArgs([]string{"abc", "pqr"})
+
+	if assert.Nil(t, cmd.Execute()) {
+		assert.LessOrEqual(t, int64(16), actual.FileCache.MaxParallelDownloads)
+	}
+}
+
 func TestTooManyCobraArgs(t *testing.T) {
 	tests := []struct {
 		name        string

tools/config-gen/config.tpl

@@ -20,6 +20,7 @@ import (
 	"time"
 	"net/url"
 
+	"github.com/googlecloudplatform/gcsfuse/v2/internal/config"
 	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
 )

tools/config-gen/params.yaml

@@ -451,7 +451,7 @@
   config-path: "file-cache.max-parallel-downloads"
   type: "int"
   usage: "Sets an uber limit of number of concurrent file download requests that are made across all files."
-  default: "-1"
+  default: "config.DefaultMaxParallelDownloads()"
 
 - flag-name: "download-chunk-size-mb"
   config-path: "file-cache.download-chunk-size-mb"