chore(spanner): migrate grpc-gcp into google-cloud-java by rahul2393 · Pull Request #13184 · googleapis/google-cloud-java

rahul2393 · 2026-05-13T15:19:26Z

Summary

Migrate grpc-gcp from GoogleCloudPlatform/grpc-gcp-java/grpc-gcp into google-cloud-java/grpc-gcp as a top-level base Maven module with existing com.google.cloud:grpc-gcp coordinates.

What changed

Imported grpc-gcp source under root grpc-gcp.
Added grpc-gcp to root Maven reactor.
Kept google-cloud-spanner depending on com.google.cloud:grpc-gcp, avoiding duplicate classes in google-cloud-spanner.
Added Release Please version marker for next grpc-gcp version 1.11.0-SNAPSHOT.
Updated sdk-platform-java/java-shared-dependencies/first-party-dependencies to manage grpc-gcp at 1.11.0-SNAPSHOT.
Kept grpc-gcp dependency management self-contained to avoid circular dependency:
- grpc-gcp does not import google-cloud-shared-dependencies.
- google-cloud-shared-dependencies can continue managing grpc-gcp through first-party-dependencies.
Updated CI package filters so grpc-gcp runs as its own package and still triggers Spanner checks when changed.
Excluded live integration tests from default grpc-gcp test compilation.
Stabilized GcpManagedChannelTest.testLogMetrics.
Added Java 8-only exclusion for Spanner native-image sources because current GraalVM nativeimage artifact requires Java 11 bytecode.

Validation

mvn -q -pl grpc-gcp test -Pquick-build
cd grpc-gcp && mvn -q dependency:analyze -DfailOnWarning=true -DskipTests -Pquick-build
mvn -q -pl java-spanner/google-cloud-spanner -am -DskipTests compile -Pquick-build
cd java-spanner && mvn -q dependency:analyze -Pquick-build -DfailOnWarning=true -Dmdep.analyze.skip=false
./generation/check_non_release_please_versions.sh

…c-gcp

gemini-code-assist

Code Review

This pull request introduces the grpc-gcp library into the google-cloud-java monorepo, including its core implementation for gRPC channel pooling, affinity management, and multi-endpoint support, along with necessary configuration updates in pom.xml and versions.txt. My review identified two potential resource management issues: the use of an unbounded CachedThreadPool for state notifications, which could lead to thread exhaustion, and the static SHARED_BACKGROUND_SERVICE executor, which lacks a proper lifecycle management, potentially causing resource leaks.

gemini-code-assist · 2026-05-13T15:25:57Z

+  private final ExecutorService stateNotificationExecutor =
+      Executors.newCachedThreadPool(
+          GcpThreadFactory.newThreadFactory("gcp-mc-state-notifications-%d"));


Using Executors.newCachedThreadPool() can lead to thread exhaustion if tasks are submitted faster than they can be processed, as it creates an unbounded number of threads. Consider using a ThreadPoolExecutor with a bounded queue and a fixed or limited number of threads to prevent potential resource exhaustion.

References

For safety, use a bounded thread pool (e.g., ThreadPoolExecutor with a defined maximum size) instead of an unbounded one (e.g., Executors.newCachedThreadPool()), even if the current logic seems to limit concurrent tasks.

gemini-code-assist · 2026-05-13T15:25:57Z

+  private static final ScheduledThreadPoolExecutor SHARED_BACKGROUND_SERVICE =
+      createSharedBackgroundService();


The SHARED_BACKGROUND_SERVICE is a static ScheduledThreadPoolExecutor that is never shut down. This can lead to a resource leak, especially in environments where the classloader might be reused or multiple instances of GcpManagedChannel are created and destroyed. Consider managing the lifecycle of this executor or using a shared, managed executor service.

blakeli0 · 2026-05-13T19:49:58Z

+      <dependency>
+        <groupId>com.google.cloud</groupId>
+        <artifactId>google-cloud-shared-dependencies</artifactId>
+        <version>${google-cloud-shared-dependencies.version}</version>


This would cause circular dependency issues that google-cloud-shared-dependencies manages grpc-gcp version and grpc-gcp also imports google-cloud-shared-dependencies.
Maven build does not error out because it does not validate declared versions in dependencyManagement sections. But it will cause issues in releasing and confusion in dependency management.

I think we have two options:

Treat grpc-gcp a top-level base library like auth. It manages its own dependencies (for now). Its version is managed by first-party-dependencies. It is imported through first-party-dependencies by downstream libraries such as Spanner.

Treat is as a sub module of Spanner and remove it from first-party-dependencies. This is a cleaner solution but it would introduce breaking changes to customers. Now my question is: Is there any grpc-gcp classes exposed on the surface and used by customers directly? If not, there are probably minimum risks.

blakeli0 · 2026-05-14T21:23:14Z

Can you update CODEOWNERS so that grpc-gcp is owned by the Spanner team?

blakeli0 · 2026-05-15T02:00:13Z

How is this file used? Are the gen code of the this proto file generated during compilation phase and shipped with the jar?

Yes. grpc_gcp.proto defines ApiConfig, MethodConfig, AffinityConfig, and ChannelPoolConfig. Those generated classes are used directly by the main code. The protobuf-maven-plugin runs during compile and it includes in the shipped jar.

blakeli0 · 2026-05-15T02:04:28Z

+  <parent>
+    <groupId>com.google.cloud</groupId>
+    <artifactId>google-cloud-shared-config</artifactId>
+    <!-- Do not depend on the version in this monorepo. It causes publication order problems. -->


This is an issue for auth but not an issue for grpc-grpc. Because the groupId of grpc-gcp is also com.google.cloud

blakeli0 · 2026-05-15T02:06:29Z

+    <junit.version>4.13.2</junit.version>
+    <opencensus.version>0.31.1</opencensus.version>
+    <opentelemetry.version>1.57.0</opentelemetry.version>
+    <spanner.version>6.118.0-SNAPSHOT</spanner.version><!-- {x-version-update:google-cloud-spanner:current} -->


Reminder: the Spanner test should be moved to Spanner module right after this PR is merged.

blakeli0 · 2026-05-15T02:07:46Z

@@ -0,0 +1,116 @@
+# gRPC-GCP for Java
+
+grpc-gcp provides gRPC support for Google Cloud Clients.


Add a blurb that this module is only used by Spanner?

blakeli0 · 2026-05-15T02:09:16Z

    <module>java-gkehub</module>
    <module>java-gkerecommender</module>
    <module>java-grafeas</module>
+    <module>java-grpc-gcp</module>


I think this module name can stay as grpc-gcp-java. All other java-* are a client library but this is more like an implementation details of the client libraries.

I can rename it to grpc-gcp-java if preferred, but we would also need to update the root POM generator/metadata flow so root-pom CI keeps it. Otherwise, the generated root POM will drop the module, root-pom CI regenerates pom.xml, and removes non-java-* modules.

I tested grpc-gcp-java against the current root POM generator image, and it has been dropped from the generated pom.xml. So using that path requires a generator change/release, not just this PR.

It should be fixed in #13211 now. I would prefer it to stay as grpc-gcp-java, similar to google-auth-library-java

Jennnnny and others added 30 commits December 17, 2018 13:16

Add the class and tests to parse the ApiConfig.json

ee66ca5

Implement the channelpool and add unit tests/ basic integration tests

e07b256

Add more tests

d23c585

Add more tests

e631332

=Add the feature of affinitykey, and add more spanner tests.

309a74b

Code refactoring, bug fixes, more spanner tests

f9f858e

Code refactoring and Bug fixes

b8df78b

using queue to deal with previous msgs

6dcf12f

Add gradle build method, handle synchronization of sendMessage()

c32d33e

Add more comments

48ee524

apply conditional var and code refactorying

22b4b4f

update method getKey() and call.request()

6bd42e8

Try to use runnable

e28bb75

bug fixes

b666875

Add bigtable 101 streams test

a88bdc8

Add bigtable tests

8ee4ec5

Merge branch 'grpc-gcp' into queue

f6b1cfa

delete pom.xml, some minor changes

959ca76

some minor changes

6e26839

fix getKey()

293db7f

reorganization

65a704f

add folder gradle

c44b1d7

Update README.md

8ee0bcb

Update bind/unbind and getKeyFromMessage

44a41d2

Merge branch 'grpc-gcp' of github.com:Jennnnny/grpc-gcp-java into grp…

688bc5a

…c-gcp

Add spanner benchmark

e4ef695

Add spanner benchmark

5476785

bug fixes

cb257a8

Add content to grpc-gcp/README.md

8fcc8ed

Change group to com.google.cloud

d490900

rahul2393 marked this pull request as ready for review May 13, 2026 15:25

rahul2393 requested review from a team as code owners May 13, 2026 15:25

gemini-code-assist Bot reviewed May 13, 2026

View reviewed changes

rahul2393 requested a review from blakeli0 May 13, 2026 15:27

rahul2393 added 2 commits May 13, 2026 21:12

fix flaky test

53fa96f

fix pom

1409dc3

rahul2393 force-pushed the migrate-grpc-gcp-java branch from 5e64f56 to 1409dc3 Compare May 13, 2026 15:58

rahul2393 added 3 commits May 13, 2026 21:28

Merge branch 'main' into migrate-grpc-gcp-java

7e835e3

fix maven test file

9b614f3

add java8 profile

9539915

blakeli0 reviewed May 13, 2026

View reviewed changes

rahul2393 added 3 commits May 14, 2026 14:01

move to separate module

3d28ec1

add pom.xml

642e2c2

fix test

ac2fa9e

rahul2393 requested a review from blakeli0 May 14, 2026 10:59

rahul2393 added 4 commits May 14, 2026 21:05

fix build

aa45641

skip native build

d06bbc2

Merge branch 'main' into migrate-grpc-gcp-java

eba6cfd

Merge branch 'main' into migrate-grpc-gcp-java

b0cea77

blakeli0 reviewed May 15, 2026

View reviewed changes

update Codeowners, and pom comments

e094728

rahul2393 requested a review from blakeli0 May 15, 2026 02:55

Merge branch 'main' into migrate-grpc-gcp-java

c0da4c3

blakeli0 mentioned this pull request May 15, 2026

fix(hermetic_build): add grpc-gcp-java to module allowlist in root pom generator #13211

Open

		private static final ScheduledThreadPoolExecutor SHARED_BACKGROUND_SERVICE =
		createSharedBackgroundService();

		@@ -0,0 +1,116 @@
		# gRPC-GCP for Java

		grpc-gcp provides gRPC support for Google Cloud Clients.

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