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Status: Available
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Pri: 3
Type: Bug



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Swarming: better handle truncated logs

Project Member Reported by robertma@chromium.org, Jul 18

Issue description

In the webkit_layout_tests step of this Windows try job: https://ci.chromium.org/p/chromium/builders/luci.chromium.try/win7_chromium_rel_ng/41337

All Swarming shards timed out (which was probably caused by my CL), but what's weird is that logs were truncated in the middle of a line (at seemingly random locations on different shards). e.g.
https://chromium-swarm.appspot.com/task?id=3ec6ae12b653a710&refresh=10&show_raw=1

Truncated logs make it hard to quickly identify the underlying bug (timeout). FWIW, these logs are printed to stderr, which isn't buffered IIUC.

In this particular example the truncation only happened on Windows, but I'm not sure if it would also happen on other OS as the timeout bug I introduced to the test runner only happened on Windows.
 
Logs are capped at 16Mb. It is assumed that logs larger than this are not human readable anyway, and leads to all sorts of performance issues.
Labels: -OS-Windows
Status: Available (was: Untriaged)
Summary: Swarming: better handle truncated logs (was: Logs truncated in the middle of a line)
An option would be to keep the last 100kb, i.e. middle out compression.
Keeping the last 100kb sounds very useful.

Besides, it'd be great to indicate in the UI that logs have been truncated.
Cc: kjlubick@chromium.org
 Issue 752908  has been merged into this issue.

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