Flash Player freezes after browser tab change

[felipe_snews]

Hi,

I have a web application running on Flash and recently some users are reporting that sometimes when they change the browser tab and then return to the app tab, it doesn't respond to any click.

After some tests, I discovered that the app isn't crashing, because when I click on a button that dispatches a request to the server, the server receives this request, but the button doesn't show visually that is being pressed.

I was able to reproduce the same freeze outside of my app with a single FLVPlayback running a video. But it isn't related to the video component because I can also reproduce by starting some "setInverval()" calls executing something with a really small interval just to simulate something running in the Flash Player.

This link I found on the web can be used as an example: http://www.dhs.state.il.us/accessibility/tests/flash/video.html. In a separated browser window, open this link in a tab and open another empty tab. Keep the Ctrl+TAB keys pressed to keep switching between the two tabs for some time. Usually, when the video is playing, it freezes after a few seconds.

So far I have personally seen this problem happen only in Chrome, but I have been told that the same thing happened in other browsers.

My Chrome version is 60.0.3112.90, running Flash Player 26.0.0.151 (both Windows 10 and OSX Sierra).

I haven't found anyone reporting a problem like this recently. Can you guys give me some help?

[felipe_snews]

Today I saw the freeze occur on the user's computer using Firefox. In it, the freeze happened easily with just one single tab switch.

So I decided to do more tests on another computer and it also happened with ease, just switching the tab once (Firefox and Chrome).

On both computers, the problem stopped after installing an earlier version of Flash Player (tested with 24 and 25). The problem is in version 26.0.0.151.

Using this another link its easier to reproduce the freeze:

Apache Flex® Tour De Flex Component Explorer

Another thing: on these computers, the application doesn't trigger any action on clicking after the freeze, different of what I said before. I don't know if it is the same problem since it now freezes easier and doesn't respond to clicks.

[Guest]

I had the same flash, flash froze, plugin turned off and everything stopped. The problem was the processor and amount of RAM

[felipe_snews]

Thanks for the answer.

This does not seem to be the problem in my case. I can use the application for hours without a problem, as long as I do not change the browser tab. If I change the tab, it freezes, whether in my application or any other site made in Flash.

[felipe_snews]

This video demonstrates the Flash Player 26 freezing problem after switching the browser tab. First I show the problem using the Apache Flex demo application, then I show the problem on a pure Flash site.

[jeromiec83223024]

Thanks for the detailed report.  I'll get a bug filed shortly.

[Guest]

Its not ideal, but I have a partial workaround for Firefox.

When you go back to a Flash running tab that isn't reacting, pull on the scroll bar on the right hand side of the screen. I have no idea why but it seems to return control to that tab. This doesn't work for streaming video but it does work for Flash games.

[Guest]

Hi,

Could you please provide me link on the bug (i can't find it here Tracker), or tell me when version/build where it fixed will be released.

[jeromiec83223024]

We were able to reproduce this under fairly extreme stress (hold alt-tab down for ~30 seconds), but it's not something that I would personally consider a high-priority bug, nor will it necessarily be easy to debug.

A fix from our side (assuming that it's even our bug) would be measured on a time-scale of months.  Until we have a diagnosis and a fix, any date that I made up would be pretty meaningless.  At the point at which there is a fix, it will become available in the beta shortly thereafter.  I don't think we've actually opened a bug up on it yet, but we spent a lot of time triaging it last week.  I'll send you the bug number once it gets filed, but you basically won't see any activity on it until it's marked fixed.

Thanks

[felipe_snews]

Did you watched my video? I'm experiencing this problem with just one tab switch. So, in this case, I don't think it's a low-priority bug.

The alt+tab stress bug seems to be a different bug from the one that I recorded.

Thanks

[jeromiec83223024]

The firefox issue in the video has similar symptoms, but appears distinct from the problem you've described in your original post.

For the symptoms in the video you posted, I'm able to reproduce it, but it seems to be introduced by a recent Firefox update.  Note that the only variable here is the Firefox version, and it appears specific to 32-bit Firefox on Windows.

I'll be more than happy to investigate this, bisect the builds to figure out what daily built introduced it, and get the appropriate bug(s) going.

PASS - MacOS 10.12.6 with Firefox 55.0.2 and Flash Player 26.0.0.151

PASS - Windows 10 version 1730, build 16184.1001 with Firefox 54.0.1 (32-bit) and Flash Player 26.0.0.151

FAIL - Windows 10 version 1730, build 16184.1001 with Firefox 55.0.2 (32-bit) and Flash Player 26.0.151

FAIL - Windows 7 with Firefox 55.0.2 (32-bit) with Flash Player 26.0.0.151

PASS - Windows 7 with Firefox 55.0.2 (64-bit) with Flash Player 26.0.0.151

For completeness, I've also tested the steps in the video on the following configurations, which did not demonstrate the problem for me:

PASS - Windows 10 version 1730, build 16184.1001 with Edge 40.16184.1001.0 and Flash Player 25.0.0.127

PASS - Windows 10 version 1730, build 16184.1001 with Chrome 60.0.3112.101 (64-bit) and Flash Player 26.0.0.151

PASS - Windows 7 with Internet Explorer 11 and Flash Player 26.0.0.151

PASS - Windows 7 with Google Chrome 59.0.3071.115 (64-bit) with Flash Player 26.0.0.131

Now, I'm also still interested in the original issue that you described on Chrome, but a handful of people on the test team have looked at it, and we can only able to reproduce it there under significant stress.  My suspicion is in that instance is that we're overwhelming the operating systems' ability to deliver IPC messages between Flash and Chrome reliably, which is why holding down alt+tab is necessary.

If your repro scenario is easier and/or more reliable, can you give me some more details like the specific OS build and version, browser and Flash versions?  If I can get a consistent repro case, the rest of the exercise becomes pretty easy.

Thanks!

[jeromiec83223024]

Here's the tracker link for the Firefox bug:

https://tracker.adobe.com/#/view/FP-4198555

[Olaf_K1]

We've a similar issue here:

Our Flex apps freezes after a few seconds after start-up by using Firefox [1]

It seems to me that this only happens when the browser window is maximized.

After resizing the window it's working again.

Please solve this issue...

Thanks!

[1]

Windows 7/64bit

Firefox 52.0

FP 26.0.0.151

[jeromiec83223024]

I would not assume that these issues are identical, particularly because 64-bit Firefox works fine in the original poster's case.

I'd recommend filing a bug over at tracker.adobe.com, including a link and steps to reproduce.  It's hard to say why it's hanging offhand, but the big thing is that 32-bit and 64-bit Firefox on Windows have differing sandbox implementations.  The fastest way to get the the bottom of it is to walk through it under a C++ debugger to see where it's hanging.

[felipe_snews]

Regarding the original issue, it is difficult to reproduce. Ctrl+TAB stress is extreme, but it is the easier way to reproduce. Normally it happens randomly, but it seems that it doesn't happen when the application is iddle. (Chrome version is 60.0.3112.90, running Flash Player 26.0.0.15, both Windows 10 and OSX Sierra).

But the second issue is the real problem. It doesn't occur only in Firefox, but also in Chrome, like Evyatar said. We suggest to our customers to use a previous FP version, but now it seems that a different freeze occur without changing tabs. After minimizing and restoring the window the application responds again. I don't have details about this freeze in the previous version right now, I'm still analyzing it.

It would be helpful to have some concrete response that I can pass on to my customers.

Thanks

[EvyatarBH]

We encounter freezing issues as well -

Windows 10 Enterprise 64-bit

Chrome Version 60.0.3112.101 (Official Build) (64-bit) & IE11

FP 26.0.0.137

Note that it doesn't take extreme measures to cause an application to freeze, as a simple tab change can cause it.

Restoring & maximizing Chrome window (which caused FP rendering) made the application responsive again, but this cannot be provided to customers as a workaround, so it is a serious issue for us, which should be fixed ASAP.

Thanks in advance,

Evyatar

[drygu2h]

I've got the same problem. You can see it here: http://www.taern.com. Just change the tab and all buttons will be disabled. When you will rescale window they are enabled again.

I can see this problem on all my swfs that are embeded with swfobject and have width/height = 100%.

[drygu2h]

Workaround found on stage3d group:

set wmode = gpu when embeding swf.

[jeromiec83223024]

One of the recent changes to the generally available Firefox versions forces Flash Player into windowless mode.  Requesting GPU mode (or direct) might help in some content instances.  I'd definitely be curious to know if people have success with that.

I still think this is a cluster of related issues, and that there's more than one discrete cause, but hopefully this does provide relief for some content authors, and helps us to tease out the other cases with unique root causes.

[felipe_snews]

I was using the direct mode from the beginning so it sure doesn't help, but the GPU mode seems to solve the problem that I reported in the video.

Before that, based on what drygu2h said, I changed the width/height from 100% to 99.9%. That stopped the freeze, but one of our customers started complaining about another situation where only the keyboard stops responding. They had to downgrade Firefox to get something stable.

[jeromiec83223024]

Yeah, that's basically in-line with our testing.  It looks like everything works fine up until Firefox 54.0.1, and breaks with the release of Firefox 55.0.2.  The current Firefox ESR is 52.0, and might be a good workaround for end-users and organizations experiencing this issue.

The bug is currently assigned to someone to bisect nightly Firefox builds until we find the changelist that introduces the issue.  Once we have the nightly build identified, we'll open a Mozilla bug for it.

[drygu2h]

wmode = gpu helped us in all our cases (in 4 different swfs to be exact ).

[Bnj-Y4uz2A]

Thanks for this workaround.

It seems to fix the issue for us as well.

What could be the side effect of setting wmode='gpu' instead of 'direct' ? different rendering ?

[qLipp]

For anyone stumbling across this and not yet found an answer, this might work for you:    Force a DOM redraw with javascript after detecting visibility changed.

            document.addEventListener('visibilitychange', function () {

                // super hAx to trigger a DOM redraw, which will kickstart flash

                // when it freezes from a tab switch

                if (!document.hidden) {

                    var flashContainer = document.getElementById("id-of-your-flash-div");

                    flashContainer.style.opacity = 0.99;

                    setTimeout(function() { flashContainer.style.opacity = 1; }, 20);

                }

            })

[jeromiec83223024]

Is this still happening for you with current versions of Flash Player and Firefox?  We marked the related bug as fixed back in October.

If it *is* still happening for you, I'd love a link to something that demonstrates it.  I don't want people to need workarounds like this where we can avoid it.