696302 - Automatically re-run valgrind with --track-origins=yes upon encountering an uninitialized-memory bug

Status: RESOLVED INCOMPLETE

(Release Engineering :: General, enhancement, P3)

Description

[Jesse Ruderman]

When a Firefox-under-Valgrind process fails
  (with Memcheck:{Cond|Param|Value*})
the process should automatically be re-run with --track-origins=yes.

This will help track down uninitialized-memory bugs, as long as they're reproducible.

Comment 1

[John Ford [:jhford] CET/CEST Berlin Time]

Does this require doing the entire thing again?  Is there a reason not to have this flag on every run?

Comment 2

[Jesse Ruderman]

> Does this require doing the entire thing again?

The entire process, yes. So if Mochitest-2 is one process, you'd have to redo Mochitest-2.

> Is there a reason not to have this flag on every run?

It slows down Valgrind by a factor of two or so. And Valgrind is already pretty slow.

So assuming* most runs don't hit new uninitialized-memory bugs, it's probably best not to have --track-origins=yes on every run.

[*] This should be true once we fix bug 696305. I suspect it's not true now.