Ankur
cd82ab9275
Companion code for the ankurm.com guide. Verified on Spring Boot 4.1.0, spring-grpc 1.1.0,
grpc-java 1.80.0, protobuf-java 4.34.2, JDK 25.0.3. results-full.txt is unedited mvn test
output: 8 tests, 0 failures. No installs needed - protoc and the gRPC codegen plugin resolve
as Maven artifacts, and every test uses the in-process transport.
_01_basics all four call types, and how their failure modes differ: iterator semantics on
server streaming, the half-close that client streaming hangs without, and the
independence of the two streams in bidi.
_02_troubleshooting
four failures reproduced then fixed - the 4 MB message limit and which side
enforces it, the absent default deadline, cancellation that never interrupts a
thread, and errors that arrive as UNKNOWN with no description.
Findings worth the commit message
- The in-process transport CANNOT enforce message size limits: it passes messages by
reference and never serialises them. A 4 MB + 1 KB message goes through cleanly in tests
and fails in production with RESOURCE_EXHAUSTED. The test asserts this rather than
pretending otherwise. Same blind spot covers compression, TLS, keepalive and LB.
- Two property names cost real time while writing this:
spring.grpc.server.inprocess.name (not in-process) and
spring.grpc.client.channel.<n>.target (singular channel, and target not address).
The second failure surfaces as UnknownHostException on the channel NAME.
- gRPC still has no default deadline, and cancellation only sets a Context flag.
74 lines
3.1 KiB
Markdown
74 lines
3.1 KiB
Markdown
# Spring gRPC with Spring Boot 4
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Companion repository for **[Spring gRPC with Spring Boot 4](https://ankurm.com/spring-grpc-spring-boot-4/)**
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on [ankurm.com](https://ankurm.com).
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The post covers the concepts. This repository adds the part that is hard to find written down: a
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symptom-first troubleshooting guide, with the failures reproduced as tests wherever a test can
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honestly reproduce them.
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Verified against **Spring Boot 4.1.0**, **spring-grpc 1.1.0**, **grpc-java 1.80.0**,
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**protobuf-java 4.34.2**, **JDK 25.0.3**. Full output in [`results-full.txt`](results-full.txt).
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---
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## Quick start
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Nothing to install — `protoc` and the gRPC codegen plugin are resolved as Maven artifacts, and every
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test runs over the in-process transport, so no port is bound.
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```console
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git clone https://ankurm.com/git.app/asmhatre/spring-grpc-boot4.git
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cd spring-grpc-boot4
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mvn test
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```
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8 tests, a few seconds.
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---
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## What is here
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| Test | Covers |
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| [`FourCallTypesTest`](src/test/java/com/ankurm/grpc/_01_basics/FourCallTypesTest.java) | Unary, server streaming, client streaming, bidirectional — and how their failure modes differ |
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| [`HardToDiagnoseTest`](src/test/java/com/ankurm/grpc/_02_troubleshooting/HardToDiagnoseTest.java) | Four failures reproduced and fixed: message size limits, missing deadlines, unobserved cancellation, useless error statuses |
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| Document | Covers |
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| [Troubleshooting](docs/01-troubleshooting.md) | Symptom-first index: every entry starts from the error message you actually see |
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The service itself ([`OrderServiceImpl`](src/main/java/com/ankurm/grpc/orders/OrderServiceImpl.java))
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is heavily commented and is where the correct patterns live — cancellation checks, half-close
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handling, `StreamObserver` thread-safety, structured errors.
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---
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## Five findings
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1. **gRPC is a first-class Boot starter now.** `spring-boot-starter-grpc-server` and
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`-grpc-client`, version-managed by the Boot BOM. A `@Service` extending the generated `ImplBase`
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is registered automatically — no `@GrpcService`, no registration code.
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2. **The in-process transport cannot enforce message size limits.** It passes messages by reference
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and never serialises them, so a 4 MB + 1 KB message sails through — and fails in production with
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`RESOURCE_EXHAUSTED`. Asserted in the test suite. The same blind spot covers compression, TLS,
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keepalive and load balancing.
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3. **Two property names that cost real time.** `spring.grpc.server.inprocess.name` (not
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`in-process`) and `spring.grpc.client.channel.<n>.target` (singular `channel`, and `target` not
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`address`). Getting the second wrong yields `UnknownHostException` on the channel *name*, which
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sends you to look at DNS.
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4. **gRPC has no default deadline.** A call without one waits forever. This is the single most
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common cause of a gRPC service that silently stops responding.
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5. **Cancellation does not interrupt your thread.** It sets a `Context` flag. A server that never
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checks it keeps working for a client that left ten minutes ago.
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---
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## Reference machine
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AMD Ryzen 5 5600U, Windows 11, `java 25.0.3+9-LTS-195`, Maven 3.9.9.
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## Licence
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MIT. See [LICENSE](LICENSE).
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