Metro Session Store throws in onTabClose during mochiperf/browser_msgmgr_01.js teardown

RESOLVED INCOMPLETE

Status

Firefox for Metro
Components
RESOLVED INCOMPLETE
5 years ago
3 months ago

People

(Reporter: Bobby Holley (parental leave - send mail for anything urgent), Unassigned)

Tracking

Firefox Tracking Flags

(Not tracked)

Details

(Whiteboard: p=0)

When trying to land bug 865745 (a major platform refactoring involving JSContexts), I ran into a failure in mochitest-metro-chrome (see bug 865745 comment 29).

The failure comes when we try to access aBrowser.__SS_extdata during teardown, which is undefined:
http://mxr.mozilla.org/mozilla-central/source/browser/metro/components/SessionStore.js#374

I hypothesized that we'd always thrown here, and that the platform changes just cause us to report the exception to onerror where we previously squelched it. To confirm my theory, I pushed a diagnostic patch to add  a try/catch block and dump() whether we throw in in onTabClose. I pushed one with the JSContext changes, and one without:

https://tbpl.mozilla.org/?tree=Try&rev=d0d7d9cabe88
https://tbpl.mozilla.org/?tree=Try&rev=97f6732f7f45

In both cases, the log shows the following:

INFO -  TEST-INFO | chrome://mochitests/content/metro/browser/metro/base/tests/mochiperf/browser_msgmgr_01.js | END msg manager 3
INFO -  Threw retrieving extData
INFO -  Threw retrieving extData
INFO -  Didn't throw retrieving extData
INFO -  INFO TEST-END | chrome://mochitests/content/metro/browser/metro/base/tests/mochiperf/browser_msgmgr_01.js | finished in 7852ms

This confirms my theory. And since we've always thrown here, we don't need to block bug 865745 on sorting this out. I'm pushing bug 865745 along with a patch to squelch the exception (which effectively mimics the old behavior). This allows the metro team to dig into this on their own time (if they want to at all).

Comment 1

5 years ago
Why is __SS_extdata undefined?
Component: Session Restore → Components
Product: Firefox → Firefox for Metro

Comment 2

5 years ago
(In reply to Jim Mathies [:jimm] from comment #1)
> Why is __SS_extdata undefined?

Nm that. I see this is in our session restore code. We haven't done much work with this. I imagine it's a timing issue since this test runs for a very short period of time.

Updated

4 years ago
Blocks: 861680
Whiteboard: p=0
(Assignee)

Updated

3 years ago
OS: Windows 8 Metro → Windows 8.1
Mass close of bugs in obsolete product https://bugzilla.mozilla.org/show_bug.cgi?id=1350354
Status: NEW → RESOLVED
Last Resolved: 3 months ago
Resolution: --- → INCOMPLETE
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