test: issue46234.go failures with "command exceeded time limit"

[bcmills]

greplogs --dashboard -md -l -e 'command exceeded time limit' --since=2021-01-01

2022-02-01T18:15:07-125c5a3/solaris-amd64-oraclerel
2021-07-01T17:07:36-eb437ba/linux-riscv64-jsing

This test was added in CL 320913 for #46234 (CC @thanm @cherrymui @mdempsky). The test runs with an apparently-arbitrary timeout to “[e]nsure that runtime traceback does not infinite loop”, but a 30-second timeout is decidedly shorter than infinity, especially when an entire program must be compiled and linked. 😅

As far as I can tell, there are only two tests that use buildrun -t today: issue46234.go and issue10958.go. And of those, the latter is disabled by default.

A good first step might be to separate the “build” and “run” steps in buildrun -t, so that the timeout only applies to the "run" portion rather than also the “build”. Or, perhaps we should increase the timeout, and probably also apply GO_TEST_TIMEOUT_SCALE from the builder environment.

If the timeouts persist, we should probably consider terminating the program with a more appropriate signal (#50436) to obtain a core dump for investigation.

[thanm]

Thanks Brian. Happy to move this test somewhere else (ex: somewhere in the package tests for cmd/compile) if that would help.

[bcmills]

I don't think moving the test would particularly help, since it already doesn't run as part of go test all for anybody.

(The tests in ../test only run as part of all.bash, not as a test for any particular package.)

[gopherbot]

Change https://golang.org/cl/382774 mentions this issue: test: apply GO_TEST_TIMEOUT_SCALE scaling to test timeouts

[bcmills]

Unfortunately the GO_TEST_TIMEOUT_SCALE does not seem to have fixed the problem. The test is still flaking on at least aix-ppc64:

# go run run.go -- fixedbugs/issue46234.go
command exceeded time limit
FAIL	fixedbugs/issue46234.go	47.668s

greplogs --dashboard -md -l -e 'command exceeded time limit' --since=2022-02-03

2022-03-17T08:43:15-599d539/aix-ppc64
2022-03-02T17:42:53-5a03cbd/aix-ppc64

[bcmills]

greplogs --dashboard -md -l -e 'command exceeded time limit' --since=2022-03-18

2022-04-13T20:16:24-72e77a7/aix-ppc64