Uncaught exception causes failure to reconnect.

[phronmophobic]

I have a discord bot that runs in the background for long periods of time that usually works great. Intermittently, I get a
WebSocketException in the logs (see log section). After that, the bot no longer appears online and doesn't receive messages. I have to shut everything down and restart the bot.

Version Information

• Clojure Version: 1.11.1
• Discljord Version: 1.3.1
• OS bot is hosted on: Linux

To Reproduce

I don't have a consistent approach to reproducing the exception, but I think there might still be enough info to attempt a fix.

Expected behavior

The bot should continue trying to reconnect.

Logs

Jul 25, 2023 12:33:26 AM discljord.connections.impl invoke
INFO: Exiting the shard loop
Exception in thread "async-dispatch-10" java.util.concurrent.ExecutionException: org.eclipse.jetty.websocket.api.WebSocketException: Session closed
	at org.eclipse.jetty.util.FutureCallback.get(FutureCallback.java:123)
	at org.eclipse.jetty.util.FutureCallback.get(FutureCallback.java:30)
	at clojure.core$deref_future.invokeStatic(core.clj:2317)
	at clojure.core$deref.invokeStatic(core.clj:2337)
	at clojure.core$deref.invoke(core.clj:2323)
	at gniazdo.core$eval32382$fn__32383.invoke(core.clj:21)
	at gniazdo.core$eval32363$fn__32364$G__32354__32371.invoke(core.clj:17)
	at gniazdo.core$connect_with_client$reify__32474.send_msg(core.clj:138)
	at discljord.connections.impl$step_shard_BANG_$heartbeat_fn__33010.invoke(impl.clj:393)
	at discljord.connections.impl$step_shard_BANG_$fn__33161$state_machine__16821__auto____33188$fn__33190.invoke(impl.clj:438)
	at discljord.connections.impl$step_shard_BANG_$fn__33161$state_machine__16821__auto____33188.invoke(impl.clj:431)
	at clojure.core.async.impl.runtime$run_state_machine.invokeStatic(runtime.clj:62)
	at clojure.core.async.impl.runtime$run_state_machine.invoke(runtime.clj:61)
	at clojure.core.async.impl.runtime$run_state_machine_wrapped.invokeStatic(runtime.clj:66)
	at clojure.core.async.impl.runtime$run_state_machine_wrapped.invoke(runtime.clj:64)
	at clojure.core.async$ioc_alts_BANG_$fn__11707.invoke(async.clj:423)
	at clojure.core.async$do_alts$fn__11638$fn__11641.invoke(async.clj:290)
	at clojure.core.async.impl.channels.ManyToManyChannel$fn__11351$fn__11352.invoke(channels.clj:100)
	at clojure.lang.AFn.run(AFn.java:22)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at clojure.core.async.impl.concurrent$counted_thread_factory$reify__11220$fn__11221.invoke(concurrent.clj:29)
	at clojure.lang.AFn.run(AFn.java:22)
	at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: org.eclipse.jetty.websocket.api.WebSocketException: Session closed
	at org.eclipse.jetty.websocket.common.WebSocketSession.outgoingFrame(WebSocketSession.java:350)
	at org.eclipse.jetty.websocket.common.WebSocketRemoteEndpoint.uncheckedSendFrame(WebSocketRemoteEndpoint.java:322)
	at org.eclipse.jetty.websocket.common.WebSocketRemoteEndpoint.sendAsyncFrame(WebSocketRemoteEndpoint.java:243)
	at org.eclipse.jetty.websocket.common.WebSocketRemoteEndpoint.sendStringByFuture(WebSocketRemoteEndpoint.java:419)
	at gniazdo.core$eval32382$fn__32383.invoke(core.clj:24)
	... 18 more

Additional context

• I'm running the bot on a dinky server
• The server is usually not doing much, but sometimes has a lot of work to do that might bog down the CPU and/or cause memory pressure on the JVM

[IGJoshua]

This looks to me like this is happening when Discord is shutting down the gateway server your bot is connected to. In that case I would expect discljord to attempt to reconnect, however I can attempt to reproduce this error with a mock discord server and see about fixing it.

Thanks for bringing it up!

If I'm right about what's caused the issue, I wouldn't expect this to be a frequent occurrence, but it is important to be aware of until it's fixed.

[phronmophobic]

Very cool. Thanks for the project. It's been great.

The problem doesn't occur too much, but I think there's something about my server usage (eg. dinky server with intermittent CPU and Memory spikes) that makes it more likely.

[phronmophobic]

My setup seems to be able to trigger the error every few days. Let me know if there's any helpful info I can collect.