Network connection seems to get stuck (without Google services)

[Socob]

Re-filing #7420 due to #7598.

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• I have searched open and closed issues for duplicates
• I am submitting a bug report for existing functionality that does not work as intended
• I have read https://github.com/signalapp/Signal-Android/wiki/Submitting-useful-bug-reports
• This isn't a feature request or a discussion topic

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Bug description

This is a revival of #7420 and may be the same issue as #6447, #6644 and #6880. I am using the official Signal APK from https://signal.org/android/apk/, so not Noise or anything like that.

For months now, Signal on Android’s network connection seems to “freeze” sporadically (once or twice per day), leaving it unable to send or receive any messages (even things like read confirmations) for long periods of time. During this time, messages can be sent and received from the Signal desktop client normally and without any delay, but none of these messages show up in the Android client. It does not make a difference whether the Android client is open or any conversations are opened – nothing happens.

It seems that Signal can be made “un-stuck” by resetting the phone’s network connection (e. g. disabling WiFi so that the phone switches to cellular data) or using “force stop” to kill and restart the Signal Android client completely. Upon one of these events, all of the messages from the intervening time period will appear in the Android client all at once.

Steps to reproduce

Unfortunately, since this seems to happen erratically, concrete steps to reproduce are a bit difficult to determine.

• Use the phone normally (not sure if longer periods of inactivity are required).
• Have someone else send you a message and/or send messages yourself from the Signal desktop client.

Actual result: No new messages (sent or received) are displayed in the Signal Android app, even if it is open. This occurs when the phone and the desktop are on the same WiFi network, so the issue is not due to poor connectivity.
Expected result: Messages should appear immediately in the Signal Android client.

Device info

Device: OnePlus One
Android version: 7.1.2 (LineageOS 14.1). I have never had Google Play services installed and Android Doze is disabled (“Battery optimization: Not optimized”) for Signal.
Signal version: 4.17.5 (but I’ve been having this issue for months now, so includes many earlier versions)

Link to debug log

https://gist.github.com/anonymous/b1f29ef755a08091528fefff299057d9

At 15:25, my phone switched to cellular data (because I went out of WiFi range). At that point, all the messages from the last hour or so appeared all at once.

This debug log was taken with Signal version 4.15.5, but the issue still occurs with the latest version (4.17.5).

[moxie0]

Thanks for the well detailed issue report. I don't have a gapps-free device, so I can't reproduce this. My preference is to let the free software folks handle the free software development, so I've added a "help wanted" tag to the issue.

[Kamkata]

I don't have a gapps-free device, so i can't reproduce this.

No problem if you don't have one. Just tell me where to ship you a Pixel 2 with copperheados.

[moxie0]

Thanks for the offer @Kamkata, but I already have too many phones and not enough time. I'd prefer it if folks who believe in free software took on some development instead.

[bisam]

This (cleaned-up) issue is connected to this and has some relevant information and more dumps: #6732

Also I would like to point you to this pull request regarding the issues: #7388

Would be awesome if someone can finish it 🎉

[maedoredyti]

It happens 10 times a day, every time the LineageOS without Google Services switches from LTE to WiFi. To cure it I kill the Signal by pressing and holding the back button on the Samsung phone. After the next run it works fine and all missing messages arrive.
But the same symptom I can observe on some not rooted Android phones with legitimate Gaaps. The cure this time is to bring the process list to the front and close all running apps.

Reboot or cold restart don't help because LTE is always first and in some seconds switched to WiFi so it generates LTE->WiFi event and your Signal is dead.

[micressor]

I confirm this Signal behavior for a long time now. It happens to me about once a day.

My current workaround: Finish the signal process with a long press on the back button and restart. After that everything works fine again.

Device info

Device: Fairphone 2 (FP2
Android version: 7.1.2 (LineageOS 14.1 without google stuff)
Signal (APK update) version: 4.17.5

[maedoredyti]

It happens also on iPhone and new Android devices which were not modified. Of course not so often but it is what it is.
It seems they don't care.
Signal process must be killed in some way to bring it back to life.
I don't know but I use all available communicators and all of them handle network changes without problem... They work perfectly without Google Services...

[bisam]

@maedoredyti Can you please add a debug log from one of the Android devices running GCM?

[dpapavas]

Although the attached debug log doesn't show anything out of the ordinary, I believe the problems discussed in this thread are probably caused by two separate issues. One is the failure to keep the websocket to the Signal server alive, discussed in #6644, #6732 and maybe elsewhere.

A separate issue, also discussed in #6732 (see this for example) is that on some devices the connection to the Signal client doesn't survive a change of network type.

[bisam]

Can people with more technical insight to the issues perhaps tell us what information we need to further lock down the issues. Since the issues persists on my device I can provide debug logs and information on my device/software. The thing is that I dont know when to best capture the logs. After starting the phone? After I notice the issue? After "soft rebooting" so the connection works again?

[dpapavas]

Unless this is an entirely different problem from the ones mentioned in the various other tickets, referred to in this thread, I don't think there's much more to investigate for the time being.

As I've mentioned, there are probably two separate issues involved in this. One of these (#6644) is more basic in nature, since it renders Signal completely unusable for many, if not all devices without GCM, and several PRs have been submitted for it. One of them (#7723, signalapp/libsignal-service-java#53) is now in the review phase, and looks like it might have a shot at being accepted.

I've been testing a patch, which addresses the other one, the one involving changes of network type (between WiFi, mobile, etc.) for a week now and it seems to be working pretty well. It attacks the problem in two separate ways by recycling the connection both when a network change is detected and also when a keep-alive request is never responded to (which is based on/inspired by signalapp/libsignal-service-java#49, which has an excellent basic mode of operation, but would likely cause more freezes, at least on my device, due to the way it's implemented).

Having both methods, is not absolutely necessary, but the first is more rapid, and should leave the device without a connection for only a few seconds, when it detects a network change, while the other is more universal, but would take longer to act (somewhere between 1-2 minutes). I have a feeling the PR will have a hard time getting accepted, but in any case I can't submit it, until the first one is through, as it concerns the same functionality of Signal and needs to be based on it.