1635799 - Missing stacks when running mochitests

Status: RESOLVED WORKSFORME

(Testing :: Mochitest, defect, P3)

Description

[Beth Rennie [:beth] (she/her)]

I was running some tests on a local linux build and was crashing but not receiving any stack output. This was due to this check in utils.py.

However, the build I was testing was an "optdebug" build, ie, optimized with both debug symbols and debug assertions. From my mozconfig:

ac_add_options --enable-optimize
ac_add_options --enable-debug
ac_add_options --enable-debug-symbols

I would therefore expect stacks to be printed during a crash.

I was able to get stacks in my crash by:

1. Removing the check in utils.py
2. Building minidump_stackwalk by adding ac_add_options --enable-project/tools/crashreporter
3. Running ./mach buildsymbols
4. Running the test with MINIDUMP_STACKWALK set to the executable from step 2.

It would be nice if this was officially supported by tooling because stacks seem possible in the situation.

Comment 1

[Beth Rennie [:beth] (she/her)]

Attachment: mochitest.log

Here is a log that results when I don't apply the workarounds outlined in the bug.

Comment 2

[Geoff Brown [:gbrown]]

The first thing I notice in the log is:

MINIDUMP_STACKWALK not set, can't process dump.

The first step in crash reporting is to run any minidumps through minidump_stackwalk, found via the MINIDUMP_STACKWALK environment variable: You do need to set that locally to get crash reports.

There has also been activity around fix-stacks, with a current discussion in https://groups.google.com/forum/#!topic/mozilla.dev.platform/y_k0X4Y6t1g ... but none of that comes into play until minidump_stackwalk has generated a crash report.

Comment 3

[Geoff Brown [:gbrown]]

Be aware that rather than building minidump_stackwalk locally, it may be easier to download one from CI, like

https://firefox-ci-tc.services.mozilla.com/tasks/index/gecko.cache.level-3.toolchains.v3.linux64-minidump-stackwalk/latest

Comment 4

[Andrew Halberstadt [:ahal]]

If I'm reading comment 2 correctly, it looks like there's no bug to fix? Do we want to resolve or is there still something to improve?

Comment 5

[Geoff Brown [:gbrown]]

With bug 1635834 (or the tc index, comment 3), minidump_stackwalk is readily available, and developers need only set their environment's MINIDUMP_STACKWALK to point to their local copy, if they want crash reports.