shunping opened a new pull request, #36227: URL: https://github.com/apache/beam/pull/36227
I have seen the following panic in one of the precommit test logs ( https://github.com/apache/beam/actions/runs/17888682703/job/50866217521?pr=36226). ``` 0: panic in ElementManager.Bundles watermark evaluation goroutine: assignment to entry in nil map goroutine 5592 [running]: runtime/debug.Stack() /home/runner/sdk/go1.24.4/src/runtime/debug/stack.go:26 +0x5e github.com/apache/beam/sdks/v2/go/pkg/beam/runners/prism/internal/engine.(*ElementManager).Bundles.func2.1() /runner/_work/beam/beam/sdks/go/pkg/beam/runners/prism/internal/engine/elementmanager.go:385 +0x39 panic({0x169b4c0?, 0x2d0a4a0?}) /home/runner/sdk/go1.24.4/src/runtime/panic.go:792 +0x132 github.com/apache/beam/sdks/v2/go/pkg/beam/runners/prism/internal/engine.set[...].insert(...) /runner/_work/beam/beam/sdks/go/pkg/beam/runners/prism/internal/engine/elementmanager.go:1131 github.com/apache/beam/sdks/v2/go/pkg/beam/runners/prism/internal/engine.tsFinalEvent.Execute({{0xc153f7fc50?, 0x15c9f40?}}, 0xc212f6bd40) /runner/_work/beam/beam/sdks/go/pkg/beam/runners/prism/internal/engine/teststream.go:256 +0xa5 github.com/apache/beam/sdks/v2/go/pkg/beam/runners/prism/internal/engine.(*ElementManager).checkForQuiescence(0xc212f6bd40, 0xc212f6bd40?) /runner/_work/beam/beam/sdks/go/pkg/beam/runners/prism/internal/engine/elementmanager.go:542 +0x17b github.com/apache/beam/sdks/v2/go/pkg/beam/runners/prism/internal/engine.(*ElementManager).Bundles.func2() /runner/_work/beam/beam/sdks/go/pkg/beam/runners/prism/internal/engine/elementmanager.go:497 +0x251 created by github.com/apache/beam/sdks/v2/go/pkg/beam/runners/prism/internal/engine.(*ElementManager).Bundles in goroutine 5582 /runner/_work/beam/beam/sdks/go/pkg/beam/runners/prism/internal/engine/elementmanager.go:381 +0x156 ``` Basically, there are a few cases where `updateWatermarks` will return a nil set(map). For example: https://github.com/apache/beam/blob/36598323b10f7ec0df4bd5a02d4a07f9fcfc9018/sdks/go/pkg/beam/runners/prism/internal/engine/elementmanager.go#L2101 In most references of `updateWatermarks`, the returned map are read not written, except for the one in test stream, where we try to insert an element to this returned set(map). Inserting to a nil map will cause a panic. https://github.com/apache/beam/blob/36598323b10f7ec0df4bd5a02d4a07f9fcfc9018/sdks/go/pkg/beam/runners/prism/internal/engine/teststream.go#L255-L256 Reference (https://go.dev/blog/maps#declaration-and-initialization): > A nil map behaves like an empty map when reading, but attempts to write to a nil map will cause a runtime panic; don’t do that. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@beam.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
