Stop reconnecting when page is hidden #6534
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This tries to address the problem of seeing the "attempting to reconnect" flash lingering around for a very long time when resuming a LiveView tab on mobile. In my tests, this mostly happens when fallback to longpoll is disabled. In this case, the following happens: 1. User puts their phone to sleep. 2. After a couple of seconds, the browser kills the websocket connection and Phoenix registers this as an error. 3. Phoenix tries to establish a new WebSocket connection. This hangs. 4. User opens the page again. Instead of immediately establishing the connection, the WebSocket is stalled for a while. The exact amount seems a bit random, but I've seen 10+ seconds. During that time, the WebSocket in the devtools doesn't show any activity, but then suddenly the connection works again. If LongPoll is active, at point 3, Phoenix instead tries a LongPoll connection. In mobile Chrome, the HTTP request fails and Phoenix registers this as 500 and tries again, backing off. If the user resumes the page - depending on their luck - they might need to wait for the next backoff attempt to fire, then the connection is established quickly. This PR addresses this problem by checking the visibility state using the `visibilitychange` event, which is recommended for registering a tab going in the background (for example by a phone going to sleep). We set a flag that we're hidden and in the case that there's an error, we don't try to reconnect immediately (since we're hidden). Instead, we reconnect as soon as the visibilitychange fires again with the page not hidden any more. With this change, the connection is immediately established in both mobile Chrome (Android) and Mobile Safari (iOS), most of the time not seeing the "trying to reconnect" flash at all. Also, this PR addresses a problem where the `connectWithFallback` function would accumulate `onOpen` listeners, causing duplicate callbacks. Hopefully closes phoenixframework/phoenix_live_view#3896. Hopefully closes #6149.
filipecabaco
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Nov 26, 2025
* Stop reconnecting when page is hidden This tries to address the problem of seeing the "attempting to reconnect" flash lingering around for a very long time when resuming a LiveView tab on mobile. In my tests, this mostly happens when fallback to longpoll is disabled. In this case, the following happens: 1. User puts their phone to sleep. 2. After a couple of seconds, the browser kills the websocket connection and Phoenix registers this as an error. 3. Phoenix tries to establish a new WebSocket connection. This hangs. 4. User opens the page again. Instead of immediately establishing the connection, the WebSocket is stalled for a while. The exact amount seems a bit random, but I've seen 10+ seconds. During that time, the WebSocket in the devtools doesn't show any activity, but then suddenly the connection works again. If LongPoll is active, at point 3, Phoenix instead tries a LongPoll connection. In mobile Chrome, the HTTP request fails and Phoenix registers this as 500 and tries again, backing off. If the user resumes the page - depending on their luck - they might need to wait for the next backoff attempt to fire, then the connection is established quickly. This PR addresses this problem by checking the visibility state using the `visibilitychange` event, which is recommended for registering a tab going in the background (for example by a phone going to sleep). We set a flag that we're hidden and in the case that there's an error, we don't try to reconnect immediately (since we're hidden). Instead, we reconnect as soon as the visibilitychange fires again with the page not hidden any more. With this change, the connection is immediately established in both mobile Chrome (Android) and Mobile Safari (iOS), most of the time not seeing the "trying to reconnect" flash at all. Also, this PR addresses a problem where the `connectWithFallback` function would accumulate `onOpen` listeners, causing duplicate callbacks. Hopefully closes phoenixframework/phoenix_live_view#3896. Hopefully closes phoenixframework#6149. * make tests happy
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This tries to address the problem of seeing the "attempting to reconnect" flash lingering around for a very long time when resuming a LiveView tab on mobile. In my tests, this mostly happens when fallback to longpoll is disabled. In this case, the following happens:
If LongPoll is active, at point 3, Phoenix instead tries a LongPoll connection. In mobile Chrome, the HTTP request fails and Phoenix registers this as 500 and tries again, backing off. If the user resumes the page - depending on their luck - they might need to wait for the next backoff attempt to fire, then the connection is established quickly.
This PR addresses this problem by checking the visibility state using the
visibilitychangeevent, which is recommended for registering a tab going in the background (for example by a phone going to sleep). We set a flag that we're hidden and in the case that there's an error, we don't try to reconnect immediately (since we're hidden). Instead, we reconnect as soon as the visibilitychange fires again with the page not hidden any more.With this change, the connection is immediately established in both mobile Chrome (Android) and Mobile Safari (iOS), most of the time not seeing the "trying to reconnect" flash at all.
Also, this PR addresses a problem where the
connectWithFallbackfunction would accumulateonOpenlisteners, causing duplicate callbacks.Hopefully closes phoenixframework/phoenix_live_view#3896.
Hopefully closes #6149.
If someone wants to test this, you can use: