Mark Mentovai e7630628e9 mac: Report richer exception codes via metrics
Previously, only the top-level exception code was reported via the
Crashpad.ExceptionCode.Mac histogram. Making this histogram work
(https://crbug.com/678720) has revealed that Chrome is triggering
EXC_RESOURCE exceptions at a rate in excess of 4x that of ordinary
crashes. These exceptions were not previously visible because they are
not uploaded unless the system treats them as fatal, which it does not
normally do absent an explicit request.

In order to learn more about the problem, this change augments the data
reported via the Crashpad.ExceptionCode.Mac histogram to report (at
least) second-level exception data. This means that we will no longer
see just EXC_RESOURCE, but potentially more useful information such as
EXC_RESOURCE / RESOURCE_TYPE_IO / FLAVOR_IO_PHYSICAL_WRITES. This also
applies to other exception types, so that the majority of crashes
currently falling into the EXC_CRASH bucket will now have additional
information decoded and will be reported as, for example, EXC_BAD_ACCESS
/ KERN_INVALID_ADDRESS, EXC_BAD_INSTRUCTION / EXC_I386_INVOP, and
EXC_CRASH / SIGABRT.

Because the old mechanism was only live (in an “it works” sense) for
several days, and the new mechanism does not overlap with histogram
values used by the old one, there’s no need to invent a new histogram
name.

BUG=chromium:684051

Change-Id: Ia0a372b4127f7b3b2e7dbbaac9304cce3b5aadfe
Reviewed-on: https://chromium-review.googlesource.com/430933
Reviewed-by: Scott Graham <scottmg@chromium.org>
2017-01-24 15:59:30 +00:00
..