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ViewsSignalR and/or timer issues since Chrome 88
We have an ASP.Net WebForms application that uses SignalR (v2.4.1) to do some bi-directional communications between server and client. It's worked fine for years: connections are stable, hundreds of users use it, etc.
However, we've started to get sporadic reports of connection problems from across our client base, all reporting the same thing: if the browser (Chrome) session goes idle for more than 5 minutes, the connection drops in the background. All timers in the page stop being run regularly, which (amongst other things) stops "keepalives" stop being sent, and eventually the connection fails with the client-side error:
The client has been inactive since <date> and it has exceeded the inactivity timeout of 50000 ms. Stopping the connection.
Standard procedure after this would be to automatically restart the connection, but this doesn't do anything. If/when the user reactivates the page (e.g. by switching to the tab), everything starts to spring back into life, albeit with a closed SignalR connection.
After much investigation, it seems that we're being impacted by this change introduced in Chrome v88, where timers (setTimeouts) are severely restricted if
- The page has been hidden for more than 5 minutes
- The timer has been "chained" 5 or more times - I'm assuming this is similar to recursion, where the timer calls itself.
- Page has been "silent" for 30 seconds
The 5 minutes/30 seconds condition fits with the reports we're getting. However, we're running pretty basic Javascript on our page: there are only two uses of setTimeout in our own code, neither of which could ever "chain" (recurse) onto themselves. We also cannot replicate the issue: it's happened to us in testing, but we can't make it happen reliably. Disabling this feature via chrome://flags/#intensive-wake-up-throttling seems to mitigate the issue - but of course, we can't make this a requirement to use our site.
The only other Javascript running on the site is jquery.signalR-2.4.1.js, and from the SignalR source, there are lots of setTimeouts in there. Could SignalR be impacted by this change in Chrome; perhaps when it tries to silently reconnect after a temporary network issue or some other unpredictable event?
If not, is there any way, in any browser or IDE, to track which timers have been launched (and, more importantly, "chained"), so we can see what could be triggering this restriction?
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We are also facing issues with our signalR (WebSockets as transport). We can't reproduce it in our lab. Our client's HAR files and extended logging gave us only the information that the client "consumes only after following interesting groups" does not send pings within the default 30 seconds required to maintain the connection. Therefore, the server closes the connection. We added logs in the signalR client library and only saw that the ping timer was not reached in time. No error, no nothing. (The client is JavaScript and the problem occurred on the client site in Chrome 87 (the limitation is already implemented there for half of Chrome users: https://support.google.com/chrome/a/answer/7679408 #87 ))
Our quick help for our clients will be to create an ET with a manual transmission ping-pong mechanism from the server site and each client will have to respond. Avoid relying on JavaScript ping on the signalR library until a "better" solution or fix is provided.
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I know that it does not solve the problem altogether with chrome, however, the new edge that uses chromium engine has added a few new settings to govern the timeouts (since it was affected too by the change). There is a new whitelisting option that gives at least the power to the users to decide which pages are excluded from this behavior. I honestly do believe that these setting will be added by google sooner or later. Until then we recommend our customers to switch to edge if they are affected.
You can find it in settings\system:
