test: pass through stderr in benchmark tests

[addaleax]

This helps a lot with debugging failing benchmark tests,
which would otherwise just print an assertion for the
exit code (something like +1 -0, which yields almost no
information about a failure).

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• commit message follows commit guidelines

[nodejs-github-bot]

@addaleax build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/297/pipeline

[Trott]

LGTM

[gireeshpunathil]

@addaleax - why is the third entry (in the stdio array) required?

[addaleax]

@gireeshpunathil I’m not sure I understand – the first one is for stdin, which we don’t really care about, the second one is for stdout (which is what we’re testing here, so we need to capture it). The third one is for stderr; that’s the debugging information that should not get lost in the parent process. The fourth one is necessary for fork() to work.

[gireeshpunathil]

my apologies - I meant the 4th entry (somehow the 0 based index concept messed up with the natural language).

The fourth one is necessary for fork() to work.

Can you please elaborate? missing to catch this. Is it for process.send to work properly?

[addaleax]

@gireeshpunathil I think process.send is the reason for it, but generally, it seems that child_process.fork() just fails if there’s no IPC file descriptor?

I think we might be able to switch to another child_process if we like, if we want to avoid that extra fd.

[addaleax]

CI: https://ci.nodejs.org/job/node-test-pull-request/15931/

[addaleax]

New CI: https://ci.nodejs.org/job/node-test-pull-request/16016/

[Trott]

CI: https://ci.nodejs.org/job/node-test-pull-request/16048/

[Trott]

Just fixed AIX in CI (I hope): https://ci.nodejs.org/job/node-test-pull-request/16049/

[trivikr]

Landed in 8a62cdb