From 6052e6e5ffc39c2dcfda7534d7f213c85dc0ee29 Mon Sep 17 00:00:00 2001
From: Sophia Yang <171981480+yangyzs@users.noreply.github.com>
Date: Fri, 14 Aug 2026 15:12:37 -0400
Subject: [PATCH] feat(internal/librarian/java): parallelize java library
 generation

Parallelize Java client library generation using errgroup, running library generation concurrently with CPU-bound worker pool. Enable integration test in workflow for validation.

TAG=agy
---
 .github/workflows/java.yaml    |  2 +-
 internal/librarian/generate.go | 14 +++++++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/java.yaml b/.github/workflows/java.yaml
index 628b950cf7e..26cac0765ed 100644
--- a/.github/workflows/java.yaml
+++ b/.github/workflows/java.yaml
@@ -116,7 +116,7 @@ jobs:
         working-directory: google-cloud-java
         run: librarian generate secretmanager
       - name: Run librarian generate all (integration test)
-        if: matrix.task == 'integration' && github.event_name == 'push' && github.ref == 'refs/heads/main'
+        if: matrix.task == 'integration'
         working-directory: google-cloud-java
         run: librarian generate --all
   create-issue-on-failure:
diff --git a/internal/librarian/generate.go b/internal/librarian/generate.go
index 6f46df842dc..ca6f67231b2 100644
--- a/internal/librarian/generate.go
+++ b/internal/librarian/generate.go
@@ -241,10 +241,18 @@ func generateLibraries(ctx context.Context, cfg *config.Config, libraries []*con
 		}
 		return g.Wait()
 	case config.LanguageJava:
+		g, gctx := errgroup.WithContext(ctx)
+		g.SetLimit(runtime.NumCPU())
 		for _, library := range libraries {
-			if err := java.Generate(ctx, cfg, library, src); err != nil {
-				return fmt.Errorf("generate library %q (%s): %w", library.Name, cfg.Language, err)
-			}
+			g.Go(func() error {
+				if err := java.Generate(gctx, cfg, library, src); err != nil {
+					return fmt.Errorf("generate library %q (%s): %w", library.Name, cfg.Language, err)
+				}
+				return nil
+			})
+		}
+		if err := g.Wait(); err != nil {
+			return err
 		}
 		if err := java.Format(ctx, libraries...); err != nil {
 			return fmt.Errorf("format java libraries (%s): %w", cfg.Language, err)