internal/trace/v2: TestTraceAnnotations failures

[gopherbot]

#!watchflakes
default <- pkg == "internal/trace/v2" && test == "TestTraceAnnotations"

Issue created automatically to collect these failures.

Example (log):

--- FAIL: TestTraceAnnotations (0.28s)
    --- FAIL: TestTraceAnnotations/Default (0.27s)
        reader_test.go:112: unexpected error while reading the trace: broken trace: failed to advance: frontier:
            [gen=1]

            M 3 [ProcStart time=469650455296 p=4 p_seq=1]

            G 3 [status=Waiting seq=0 (gen=1)]
            G 4 [status=Waiting seq=0 (gen=1)]
            G 5 [status=Waiting seq=0 (gen=1)]
...
            String id=65
            	data="internal/poll.(*FD).Write"
            String id=66
            	data="os.(*File).write"
            String id=67
            	data="/tmp/workdir/go/src/os/file_posix.go"
            String id=68
            	data="os.(*File).Write"
            String id=69
            	data="/tmp/workdir/go/src/os/file.go"

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "internal/trace/v2" && test == "TestTraceAnnotations"

2024-01-19 21:39 dragonfly-amd64-622 go@7cb98c1d internal/trace/v2.TestTraceAnnotations (log)

--- FAIL: TestTraceAnnotations (0.28s)
    --- FAIL: TestTraceAnnotations/Default (0.27s)
        reader_test.go:112: unexpected error while reading the trace: broken trace: failed to advance: frontier:
            [gen=1]

            M 3 [ProcStart time=469650455296 p=4 p_seq=1]

            G 3 [status=Waiting seq=0 (gen=1)]
            G 4 [status=Waiting seq=0 (gen=1)]
            G 5 [status=Waiting seq=0 (gen=1)]
...
            String id=65
            	data="internal/poll.(*FD).Write"
            String id=66
            	data="os.(*File).write"
            String id=67
            	data="/tmp/workdir/go/src/os/file_posix.go"
            String id=68
            	data="os.(*File).Write"
            String id=69
            	data="/tmp/workdir/go/src/os/file.go"

— watchflakes

[mknyszek]

I see the problem. There's a missing ProcSteal event here. The strange part is that the runtime ended the trace before emitting it, which shouldn't be possible. It's either that, or the GoSyscallBegin was actually blocking to start with and failed to emit a ProcStop event.

[gopherbot]

Change https://go.dev/cl/560235 mentions this issue: runtime: traceAcquire and traceRelease across all P steals