runtime:mayMoreStackPreempt: TestGoroutineLeakProfile/Moby27782 failures

[gopherbot]

#!watchflakes
default <- pkg == "runtime:mayMoreStackPreempt" && test == "TestGoroutineLeakProfile/Moby27782"

Issue created automatically to collect these failures.

Example (log):

=== RUN   TestGoroutineLeakProfile/Moby27782
=== PAUSE TestGoroutineLeakProfile/Moby27782
=== CONT  TestGoroutineLeakProfile/Moby27782
    goroutineleakprofile_test.go:510: /Users/swarming/.swarming/w/ir/x/t/go-build3091866055/testgoroutineleakprofile/goker.exe Moby27782 (274.24ms): ok
    goroutineleakprofile_test.go:510: /Users/swarming/.swarming/w/ir/x/t/go-build3091866055/testgoroutineleakprofile/goker.exe Moby27782: exit status 2
    goroutineleakprofile_test.go:517: unexpected fatal exception or panic!
        output:
        fatal error: concurrent map iteration and map write
        
        goroutine 12906 [running]:
...
        main.followLogs_moby27782(0x19f89db10a98)
        	/Users/swarming/.swarming/w/ir/x/w/goroot/src/runtime/testdata/testgoroutineleakprofile/goker/moby27782.go:166 +0x38
        main.(*JSONFileLogger_moby27782).readLogs(...)
        	/Users/swarming/.swarming/w/ir/x/w/goroot/src/runtime/testdata/testgoroutineleakprofile/goker/moby27782.go:222
        created by main.(*JSONFileLogger_moby27782).ReadLogs in goroutine 12921
        	/Users/swarming/.swarming/w/ir/x/w/goroot/src/runtime/testdata/testgoroutineleakprofile/goker/moby27782.go:216 +0xb0
        
        
    goroutineleakprofile_test.go:510: /Users/swarming/.swarming/w/ir/x/t/go-build3091866055/testgoroutineleakprofile/goker.exe Moby27782 (271.420042ms): ok
--- FAIL: TestGoroutineLeakProfile/Moby27782 (1.00s)

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "runtime:mayMoreStackPreempt" && test == "TestGoroutineLeakProfile/Moby27782"

2025-10-02 18:30 gotip-darwin-arm64-longtest go@707454b4 runtime:mayMoreStackPreempt.TestGoroutineLeakProfile/Moby27782 (log)

=== RUN   TestGoroutineLeakProfile/Moby27782
=== PAUSE TestGoroutineLeakProfile/Moby27782
=== CONT  TestGoroutineLeakProfile/Moby27782
    goroutineleakprofile_test.go:510: /Users/swarming/.swarming/w/ir/x/t/go-build3091866055/testgoroutineleakprofile/goker.exe Moby27782 (274.24ms): ok
    goroutineleakprofile_test.go:510: /Users/swarming/.swarming/w/ir/x/t/go-build3091866055/testgoroutineleakprofile/goker.exe Moby27782: exit status 2
    goroutineleakprofile_test.go:517: unexpected fatal exception or panic!
        output:
        fatal error: concurrent map iteration and map write
        
        goroutine 12906 [running]:
...
        main.followLogs_moby27782(0x19f89db10a98)
        	/Users/swarming/.swarming/w/ir/x/w/goroot/src/runtime/testdata/testgoroutineleakprofile/goker/moby27782.go:166 +0x38
        main.(*JSONFileLogger_moby27782).readLogs(...)
        	/Users/swarming/.swarming/w/ir/x/w/goroot/src/runtime/testdata/testgoroutineleakprofile/goker/moby27782.go:222
        created by main.(*JSONFileLogger_moby27782).ReadLogs in goroutine 12921
        	/Users/swarming/.swarming/w/ir/x/w/goroot/src/runtime/testdata/testgoroutineleakprofile/goker/moby27782.go:216 +0xb0
        
        
    goroutineleakprofile_test.go:510: /Users/swarming/.swarming/w/ir/x/t/go-build3091866055/testgoroutineleakprofile/goker.exe Moby27782 (271.420042ms): ok
--- FAIL: TestGoroutineLeakProfile/Moby27782 (1.00s)

— watchflakes

[mknyszek]

There appears to be a real race here. We should just fix this in the test.

[gopherbot]

Change https://go.dev/cl/710756 mentions this issue: runtime: fail TestGoroutineLeakProfile on data race