nielm opened a new issue, #32697:
URL: https://github.com/apache/beam/issues/32697
### What happened?
#31663 introduced a regression in Dataflow for streaming pipelines using
spannerIO
Spanner has a max number of 400 sessions in a session pool, where a session
is used for a read or a write operation.
When using streaming pipelines on Dataflow with a high degree of
parallelisation, where each work item can be both reading from and writing to
spanner, Dataflow will have up to 300 threads per worker, which potentially
means 300 simultaneous read sessions, and 300 simultaneous downstream writes.
In some scenarios, this can lead to session pool exhaustion, followed by a
worker failing due to this flag with the following stack trace:
```
Error message from worker: generic::unknown:
org.apache.beam.sdk.util.UserCodeException:
com.google.cloud.spanner.SpannerException: RESOURCE_EXHAUSTED: No session
available in the pool. Maximum number of sessions in the pool can be overridden
by invoking
SessionPoolOptions#Builder#setMaxSessions. Client can be made to block
rather than fail by setting
SessionPoolOptions#Builder#setBlockIfPoolExhausted.
There are currently 400 sessions checked out:
com.google.cloud.spanner.SessionPool$LeakedSessionException: Session was
checked out from the pool at 2024-10-03T08:30:13.020Z
com.google.cloud.spanner.SessionPool$PooledSessionFuture.markCheckedOut(SessionPool.java:1338)
com.google.cloud.spanner.SessionPool$PooledSessionFuture.access$6200(SessionPool.java:1317)
com.google.cloud.spanner.SessionPool.checkoutSession(SessionPool.java:3270)
```
reverted in #32694
### Issue Priority
Priority: 2 (default / most bugs should be filed as P2)
### Issue Components
- [ ] Component: Python SDK
- [X] Component: Java SDK
- [ ] Component: Go SDK
- [ ] Component: Typescript SDK
- [ ] Component: IO connector
- [ ] Component: Beam YAML
- [ ] Component: Beam examples
- [ ] Component: Beam playground
- [ ] Component: Beam katas
- [ ] Component: Website
- [ ] Component: Infrastructure
- [ ] Component: Spark Runner
- [ ] Component: Flink Runner
- [ ] Component: Samza Runner
- [ ] Component: Twister2 Runner
- [ ] Component: Hazelcast Jet Runner
- [ ] Component: Google Cloud Dataflow Runner
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