1436573 - [Intermittent] Sync icon is spinning indefinitely

Status: RESOLVED DUPLICATE of bug 1436637

(Firefox :: Sync, defect)

Description

[Abe - QA (:Abe_LV)]

Screen captures- https://testing-1.tinytake.com/sf/MjMzODAzNl83MTQ0NzA3
Even though it is intermittent, it is reproducible 10-20% of the time.

Steps to reproduce:
1. Login to sync
2. Click the sync icon to sync
3. Observe the sync icon spinning.

Actual result
The sync icon spins indefinitely

Expected Result
Icon should spin for some time

yesterday it crashed when I restart the browser from the developer toolbar.
The crash is here- https://crash-stats.mozilla.com/report/index/a0c580af-9d1d-4621-963c-6941a0180206

Today, I deliberately crashed it (killed the process) while it is on an infinite spinning. The crash is here- https://crash-stats.mozilla.com/report/index/f218dee7-b096-4f99-9221-0c3780180207

Comment 1

[Lina Butler (ex-Mozilla)]

This is with `services.sync.engine.bookmarks.buffer` enabled, right?

Comment 2

[Abe - QA (:Abe_LV)]

(In reply to Kit Cambridge (they/them) [:kitcambridge] from comment #1)
> This is with `services.sync.engine.bookmarks.buffer` enabled, right?

That pref is false for the second case. It does not depends on that pref for my case.

Comment 3

[Mark Hammond [:markh] [:mhammond]]

That sounds like a significant problem. Making it more complicated is that we probably will not write log files in that case. Would it be possible to:

* Install the https://addons.mozilla.org/en-US/firefox/addon/about-sync/ addon and ensure "Level of messages written by Sync engines" *and* "Level of messages written to dump - useful primarily for developers" are both set to "Trace".

* Start the browser from a console/terminal, redirecting all output to a file - eg, "firefox -P etc 2>&1 > output.log" and let a sync run.

* Verify that output.log does indeed see sync logging.

* Reproduce the issue, then attach output.log here.

Please let us know if any of that doesn't work

Comment 4

[Mark Hammond [:markh] [:mhammond]]

Oh - you probably also need to set the preference "browser.dom.window.dump.enabled" to "true"

Comment 5

[Abe - QA (:Abe_LV)]

Attachment: error-sync-1518046532213.txt

Just tried it on Ubuntu 16.04 and still able to get the infinite spinning. The buffer pref is false and I do not think it is logging during this condition.

New Screen capture - https://testing-1.tinytake.com/sf/MjMzODIzN183MTQ1MTYw

I have error logs but I do not think they are from the spinning. I will attach three of them.

I do have the addon installed [About Sync extension for Firefox] and "Level of messages written by Sync engines" and "Level of messages written to about:sync-logs log files" are also set to "Trace"

Comment 6

[Abe - QA (:Abe_LV)]

Attachment: error-sync-1518046532635.txt

Comment 7

[Abe - QA (:Abe_LV)]

Attachment: error-sync-1518046857722.txt

Comment 8

[Lina Butler (ex-Mozilla)]

Thanks, Abe! These lines are definitely relevant, but, unfortunately, don't give clues about why the sync is stuck...probably because the stuck sync before this one never finishes, and so we never flush the log file.

> 1518046852649	Sync.Service	DEBUG	Exception calling anonymous function: LockException: Could not acquire lock. Label: "service.js: sync". (resource://services-sync/util.js:41:5) JS Stack trace: [e-mail]:41:5 < [e-mail]:117:11 < [e-mail]:131:9 < async*[e-mail]:1118:12 < async*sync/<@service.js:1110:13 < async*[e-mail]:105:22 < async*[e-mail]:1099:12 < async*syncIfMPUnlocked/<@policies.js:525:7
> 1518046852652	Sync.Service	INFO	Cannot start sync: already syncing?

If you could enable `browser.dom.window.dump.enabled`, run Firefox from the terminal, and redirect output to a file as Mark suggests in comment 3, that would be awesome. It'll bypass the log file machinery and just dump everything, which might show what's happening in the sync that never finishes.

Comment 9

[Abe - QA (:Abe_LV)]

I or Kanchan will attach the log file when we reproduce it again. I am not reproducing it right now.

Comment 10

[Mark Hammond [:markh] [:mhammond]]

Thanks Abe! Just to confirm, you are redirecting Firefox's output and see sync info in that log file, but just can't currently repro, right? (I just want to make sure you are all setup to have the logs when it does repro)

Comment 11

[Mark Hammond [:markh] [:mhammond]]

I suspect this is actually bug 1436637 which should hopefully be in tomorrow's Nightly.