637206 - Random pauses while watching Hulu videos

Status: VERIFIED FIXED

(Core Graveyard :: Plug-ins, defect)

Description

[Stuart Parmenter]

I am running Flash 10.2 r152 and today's nightly.  I see random video pauses (maybe 500ms-1s long) while watching content on Hulu.  The content doesn't seem to matter as I see it on most sites.  I'm not sure exactly when this started, but it started fairly recently.

Comment 1

[Mike Beltzner [:beltzner, not reading bugmail]]

Andreas/Stuart: can you try to find each other on Monday and take a look at this? Just seems like the easiest way to figure out what's going on.

Comment 2

[Andreas Gal :gal]

Stuart, can you reproduce this in a build with symbols, and if so, can you please profile the build during the pause?

Comment 3

[Josh Aas]

I started seeing this fairly recently around the same time I saw significant GC fixes going in. 1-2 weeks ago.

Comment 4

[Andreas Gal :gal]

Guys, seriously, you know the drill. I need some specifics here. Platform, STR, what video, what other tabs were open, what other extensions were installed, how long do I have to watch the video, how frequent are the pauses. Come on.

Comment 5

[Stuart Parmenter]

This is Windows 7 (x64), STR: Go to Hulu and click on a video.  Other tabs open include Zimbra and Gmail -- No extensions.  I see the pauses pretty much start right away.

Comment 6

[Andreas Gal :gal]

Can you close all other tabs and see if this still reproduces?

Comment 7

[Andreas Gal :gal]

Attachment: patch

Enable javascript.options.mem.log to see whats going on here. A CC triggers and collects a few objects (6-ish), which schedules another full GC since those cycles might have freed up GC objects, which again triggers a CC which frees another 6-ish objects. Rinse repeat every 5s.

Without additional tabs open the pauses are not really visible, but opening 2 additional gmail tabs makes things really bad. I am seeing 500ms GC pauses. Thats ridiculous.

There are two bugs here. The attached patch only triggers a GC after a CC if we freed at least 250 objects. This calms down the CC/GC iterations a lot. I can watch a long video without seeing any GC/CC happening as long background tabs don't do a lot of JS execution.

The other bug is the 500ms GC pauses. WTF? Those are full GC, but still, 500ms is a billion cycles on my machine. The GC heap isn't that large. We must be doing something wrong. I will whip out shark and see whats up. New bug for that if appropriate. This patch should help stuart.

Please verify.

Comment 8

[Andreas Gal :gal]

I made a patch to always enable gc timing and dump it to the error console:

GC mode: full, timestamp: 1777092705, total: 0 ms, mark: 269 ms, sweep (total/obj/str/shapes/chunks): 58 ms/48 ms/4 ms/5 ms/1 ms

269ms mark time. Ridiculous. The attached patch nicely avoids most GCs while watching hulu no matter how many tabs I have open so I am confident about that part of the fix, but I am very worried about these massive mark times.

Comment 9

[Andreas Gal :gal]

Note: avoiding GCs like this is not a good idea in general. This keeps cycles alive longer and might cause bloat. We have to get our mark times under control. Everything else is just whack-a-mole.

Comment 10

[Olli Pettay [:smaug][[e-mail]]]

Comment on attachment 515535 [details] [diff] [review]
patch

We should not allow endless CC calls without GC.
Could you perhaps make 'collected' a static variable which is always
increased by the number of collected objects, and if after that the value is
> 250, PokeGC()

Comment 11

[Olli Pettay [:smaug][[e-mail]]]

Attachment: patch

Something like this. Hulu isn't accessible here, so I can't test this.

Comment 12

[Andreas Gal :gal]

Comment on attachment 515634 [details] [diff] [review]
patch

I will test it.

Comment 13

[Andreas Gal :gal]

http://hg.mozilla.org/tracemonkey/rev/f1e0fac5d508

Comment 14

[Andreas Gal :gal]

Stuart, can you please verify that this bug is fixed? (you need a TM build)

Comment 15

[Olli Pettay [:smaug][[e-mail]]]

http://tbpl.mozilla.org/?tree=Firefox

Comment 16

[Jesse Ruderman]

ITYM http://hg.mozilla.org/mozilla-central/rev/92b0df2936fe

Comment 17

[Olli Pettay [:smaug][[e-mail]]]

Oops, I pasted a very wrong link.
Thanks Jesse.

Comment 18

[Andreas Gal :gal]

http://hg.mozilla.org/mozilla-central/rev/f1e0fac5d508

Comment 19

[Maniac Vlad Florin (:vladmaniac)]

Verified with Flash Version: 10.2.152.26