Fixed the issue Unclear buildbot failure email

[slydiman]

#65

Listen to the header TTY stream and monitor the message like command timed out: 1200 seconds without output running [b'ninja', b'check-clang-unit'], attempting to kill sent from a worker.

[slydiman]

The email before this patch:

Subject: ☠ Buildbot (<SERVER>): <builder> - failed test (failure) (main)
                
The Buildbot has detected a new failure on builder <builder> while building llvm.
...                
BUILD FAILED: failed test (failure)
               
Step 8 (test-build-unified-tree-check-clang-unit) failure: test (failure)
...

The email after this patch:

Subject: ☠ Buildbot (<SERVER>): <builder> - failed 1200 seconds without output running [b'ninja', b'check-clang-unit'], attempting to kill (main)
                
The Buildbot has detected a new failure on builder <builder> while building llvm.
...                
BUILD FAILED: failed 1200 seconds without output running [b'ninja', b'check-clang-unit'], attempting to kill
                
Step 8 (test-build-unified-tree-check-clang-unit) failure: 1200 seconds without output running [b'ninja', b'check-clang-unit'], attempting to kill
...

[gkistanova]

Thanks, Dmitry!

Is it possible to skip/remove the ", attempting to kill (main)" trailing part of the string? This does not seem relevant to the problem summary.

Everything else looks good.

[slydiman]

Is it possible to skip/remove the ", attempting to kill (main)" trailing part of the string? This does not seem relevant to the problem summary.

Note (main) is the part of the summary formatting in the buildbot.
Currently the worker contains the following code

    def kill(self, msg):
        # This may be called by the timeout, or when the user has decided to abort this build.
        self._cancelTimers()
        msg += ", attempting to kill"
        log.msg(msg)
        self.send_update([('header', "\n" + msg + "\n")])
        ...

We can adjust the regex to skip , attempting to kill, but I'd rather keep it. Just a timeout doesn't tell you what finally happened. I think attempting to kill explains why some tests may be incorrectly marked as FAIL.

[vvereschaka]

Probably something like reachedTimout and timeoutReason would be more correct naming instead for those killed and killReason, but it also looks ok for now.

[gkistanova]

LGTM.