sync: add --concurrency flag

NEXT_CHANGELOG.md

@@ -6,6 +6,7 @@
 
 * `databricks api` now works against unified hosts. Adds `--account` to scope a call to the account API and `--workspace-id` to override the workspace routing identifier per call. A `?o=<workspace-id>` query parameter on the path (the SPOG URL convention used by the Databricks UI) is also recognized as a per-call workspace override, so URLs pasted from the browser route correctly.
 * JSON output for single objects now uses standard `"key": "value"` spacing (matching list output and `encoding/json` defaults).
+* Add `--concurrency` flag to `databricks sync` and `databricks bundle sync` to control the number of parallel requests to the workspace (default 20). Useful when uploading many medium-sized files where the previous fixed concurrency could trigger stream timeouts ([#5197](https://github.com/databricks/cli/pull/5197)).
 
 ### Bundles
 * Validate that resource keys do not contain variable references ([#5169](https://github.com/databricks/cli/pull/5169))

acceptance/bundle/help/bundle-sync/output.txt

@@ -15,6 +15,7 @@ Usage:
   databricks bundle sync [flags]
 
 Flags:
+      --concurrency int     number of parallel requests to the workspace (default 20)
       --dry-run             simulate sync execution without making actual changes
       --full                perform full synchronization (default is incremental)
   -h, --help                help for sync

acceptance/cmd/sync-without-args/output.txt

@@ -6,6 +6,7 @@ Usage:
   databricks sync [flags] SRC DST
 
 Flags:
+      --concurrency int       number of parallel requests to the workspace (default 20)
       --dry-run               simulate sync execution without making actual changes
       --exclude strings       patterns to exclude from sync (can be specified multiple times)
       --exclude-from string   file containing patterns to exclude from sync (one pattern per line)

cmd/bundle/sync.go

@@ -2,6 +2,7 @@ package bundle
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"time"
@@ -16,12 +17,22 @@ import (
 	"github.com/spf13/cobra"
 )
 
+var errInvalidConcurrency = errors.New("--concurrency must be at least 1")
+
 type syncFlags struct {
-	interval time.Duration
-	full     bool
-	watch    bool
-	output   flags.Output
-	dryRun   bool
+	interval    time.Duration
+	full        bool
+	watch       bool
+	output      flags.Output
+	dryRun      bool
+	concurrency int
+}
+
+func (f *syncFlags) validate() error {
+	if f.concurrency < 1 {
+		return errInvalidConcurrency
+	}
+	return nil
 }
 
 func (f *syncFlags) syncOptionsFromBundle(cmd *cobra.Command, b *bundle.Bundle) (*sync.SyncOptions, error) {
@@ -48,6 +59,7 @@ func (f *syncFlags) syncOptionsFromBundle(cmd *cobra.Command, b *bundle.Bundle)
 	opts.Full = f.full
 	opts.PollInterval = f.interval
 	opts.DryRun = f.dryRun
+	opts.Concurrency = f.concurrency
 	return opts, nil
 }
 
@@ -74,8 +86,13 @@ Use 'databricks bundle deploy' for full resource deployment.`,
 	cmd.Flags().BoolVar(&f.watch, "watch", false, "watch local file system for changes")
 	cmd.Flags().Var(&f.output, "output", "type of the output format")
 	cmd.Flags().BoolVar(&f.dryRun, "dry-run", false, "simulate sync execution without making actual changes")
+	cmd.Flags().IntVar(&f.concurrency, "concurrency", sync.MaxRequestsInFlight, "number of parallel requests to the workspace")
 
 	cmd.RunE = func(cmd *cobra.Command, args []string) error {
+		if err := f.validate(); err != nil {
+			return err
+		}
+
 		b, err := utils.ProcessBundle(cmd, utils.ProcessOptions{})
 		if err != nil {
 			return err

cmd/sync/sync.go

@@ -24,6 +24,8 @@ import (
 	"github.com/spf13/cobra"
 )
 
+var errInvalidConcurrency = errors.New("--concurrency must be at least 1")
+
 type syncFlags struct {
 	// project files polling interval
 	interval    time.Duration
@@ -35,6 +37,7 @@ type syncFlags struct {
 	dryRun      bool
 	excludeFrom string
 	includeFrom string
+	concurrency int
 }
 
 func readPatternsFile(filePath string) ([]string, error) {
@@ -89,6 +92,7 @@ func (f *syncFlags) syncOptionsFromBundle(cmd *cobra.Command, args []string, b *
 	opts.Include = append(opts.Include, f.include...)
 	opts.Include = append(opts.Include, includePatterns...)
 	opts.DryRun = f.dryRun
+	opts.Concurrency = f.concurrency
 	return opts, nil
 }
 
@@ -163,6 +167,7 @@ func (f *syncFlags) syncOptionsFromArgs(cmd *cobra.Command, args []string) (*syn
 
 		OutputHandler: outputHandler,
 		DryRun:        f.dryRun,
+		Concurrency:   f.concurrency,
 	}
 	return &opts, nil
 }
@@ -187,14 +192,20 @@ func New() *cobra.Command {
 	cmd.Flags().StringVar(&f.excludeFrom, "exclude-from", "", "file containing patterns to exclude from sync (one pattern per line)")
 	cmd.Flags().StringVar(&f.includeFrom, "include-from", "", "file containing patterns to include to sync (one pattern per line)")
 	cmd.Flags().BoolVar(&f.dryRun, "dry-run", false, "simulate sync execution without making actual changes")
+	cmd.Flags().IntVar(&f.concurrency, "concurrency", sync.MaxRequestsInFlight, "number of parallel requests to the workspace")
 
 	// Wrapper for [root.MustWorkspaceClient] that disables loading authentication configuration from a bundle.
 	mustWorkspaceClient := func(cmd *cobra.Command, args []string) error {
 		cmd.SetContext(root.SkipLoadBundle(cmd.Context()))
 		return root.MustWorkspaceClient(cmd, args)
 	}
 
-	cmd.PreRunE = mustWorkspaceClient
+	cmd.PreRunE = func(cmd *cobra.Command, args []string) error {
+		if f.concurrency < 1 {
+			return errInvalidConcurrency
+		}
+		return mustWorkspaceClient(cmd, args)
+	}
 	cmd.RunE = func(cmd *cobra.Command, args []string) error {
 		var opts *sync.SyncOptions
 		var err error

cmd/sync/sync_test.go

@@ -32,12 +32,13 @@ func TestSyncOptionsFromBundle(t *testing.T) {
 		},
 	}
 
-	f := syncFlags{}
+	f := syncFlags{concurrency: 5}
 	opts, err := f.syncOptionsFromBundle(New(), []string{}, b)
 	require.NoError(t, err)
 	assert.Equal(t, tempDir, opts.LocalRoot.Native())
 	assert.Equal(t, "/Users/jane@doe.com/path", opts.RemotePath)
 	assert.Equal(t, filepath.Join(tempDir, ".databricks", "bundle", "default"), opts.SnapshotBasePath)
+	assert.Equal(t, 5, opts.Concurrency)
 	assert.NotNil(t, opts.WorkspaceClient)
 }
 
@@ -56,13 +57,14 @@ func TestSyncOptionsFromArgs(t *testing.T) {
 	local := t.TempDir()
 	remote := "/remote"
 
-	f := syncFlags{}
+	f := syncFlags{concurrency: 7}
 	cmd := New()
 	cmd.SetContext(cmdctx.SetWorkspaceClient(t.Context(), nil))
 	opts, err := f.syncOptionsFromArgs(cmd, []string{local, remote})
 	require.NoError(t, err)
 	assert.Equal(t, local, opts.LocalRoot.Native())
 	assert.Equal(t, remote, opts.RemotePath)
+	assert.Equal(t, 7, opts.Concurrency)
 }
 
 func TestExcludeFromFlag(t *testing.T) {

libs/sync/sync.go

@@ -43,6 +43,8 @@ type SyncOptions struct {
 	OutputHandler OutputHandler
 
 	DryRun bool
+
+	Concurrency int
 }
 
 type Sync struct {
@@ -96,6 +98,10 @@ func New(ctx context.Context, opts SyncOptions) (*Sync, error) {
 		return nil, errors.New("failed to resolve host for snapshot")
 	}
 
+	if opts.Concurrency <= 0 {
+		opts.Concurrency = MaxRequestsInFlight
+	}
+
 	// For full sync, we start with an empty snapshot.
 	// For incremental sync, we try to load an existing snapshot to start from.
 	var snapshot *Snapshot

libs/sync/watchdog.go

@@ -96,9 +96,9 @@ func groupRunSingle(ctx context.Context, group *errgroup.Group, fn func(context.
 	})
 }
 
-func groupRunParallel(ctx context.Context, paths []string, fn func(context.Context, string) error) error {
+func groupRunParallel(ctx context.Context, paths []string, limit int, fn func(context.Context, string) error) error {
 	group, ctx := errgroup.WithContext(ctx)
-	group.SetLimit(MaxRequestsInFlight)
+	group.SetLimit(limit)
 
 	for _, path := range paths {
 		groupRunSingle(ctx, group, fn, path)
@@ -110,31 +110,32 @@ func groupRunParallel(ctx context.Context, paths []string, fn func(context.Conte
 
 func (s *Sync) applyDiff(ctx context.Context, d diff) error {
 	var err error
+	limit := s.Concurrency
 
 	// Delete files in parallel.
-	err = groupRunParallel(ctx, d.delete, s.applyDelete)
+	err = groupRunParallel(ctx, d.delete, limit, s.applyDelete)
 	if err != nil {
 		return err
 	}
 
 	// Delete directories ordered by depth from leaf to root.
 	for _, group := range d.groupedRmdir() {
-		err = groupRunParallel(ctx, group, s.applyRmdir)
+		err = groupRunParallel(ctx, group, limit, s.applyRmdir)
 		if err != nil {
 			return err
 		}
 	}
 
 	// Create directories (leafs only because intermediates are created automatically).
 	for _, group := range d.groupedMkdir() {
-		err = groupRunParallel(ctx, group, s.applyMkdir)
+		err = groupRunParallel(ctx, group, limit, s.applyMkdir)
 		if err != nil {
 			return err
 		}
 	}
 
 	// Put files in parallel.
-	err = groupRunParallel(ctx, d.put, s.applyPut)
+	err = groupRunParallel(ctx, d.put, limit, s.applyPut)
 
 	return err
 }