EsotericSoftware
Server.close() hangs for several seconds/minutes
When calling Server.close(), the thread will hang anywhere from a few seconds to 10+ minutes. On older, slower computers, the hang can last over half an hour. Client.close() has a similar problem but will only hang up to a few seconds. Occasionally, the hang ends with a ClosedSelectorException. This problem was introduced in a7e966136798b8e8cd8898bc461e014ed4029d09, which was a fix to #93. Tested on Linux (Lubuntu) using the ChatServer example.
Simply running new ChatServer() (from the examples folder) and closing the window causes a long delay before the JVM finally exits. All 3 linux machines I tested it on had the same problem; not sure about Windows.
I can confirm this problem. It also happens sometimes when trying to connect to the server. I tried to reproduce it. I'm not sure if it works on your machine.
// Client#connect calls Client#close() internally. This leads to the process getting stuck (sometimes).
// See Client#close(), selector.selectNow().
Server server = new Server();
server.start();
server.bind(54555, 54777);
// Required. Works otherwise.
new Thread(new Runnable() {
public void run() {
while (true) {
System.out.println("work");
}
}
}).start();
// Wait for the worker to start.
Thread.sleep(1000);
Client client = new Client();
client.start();
// It may be necessary to increase the timeout.
client.connect(5000, "localhost", 54555, 54777);
I don't recall ever having an issue with connecting (at least not to the same extreme as Server.close()) but I can see how that could be related to the same problem with the internal call to close() in connect().
I've occasionally had minor issues while connecting, and definitely have had that issue while disconnecting.
I'm on Windows 10, using libGDX, Java 14 with feature preview, on IntelliJ 2020.1.2.
@NathanSweet any updates regarding the provided piece of code?
@luisfonsivevo Do you happen to call server.dispose() on your server?
See Issue https://github.com/EsotericSoftware/kryonet/issues/82. When I commented the call to my client.dispose(), my problem disappeared.
With client.dispose()
Hanging thread, with non-responding libGDX app not actually closing after closing the window. However, I do get the following log:
00:10 INFO: [kryonet] Connection 10 disconnected.
Exception in thread "Client" java.nio.channels.ClosedSelectorException
at java.base/sun.nio.ch.SelectorImpl.ensureOpen(SelectorImpl.java:80)
at java.base/sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:123)
at java.base/sun.nio.ch.SelectorImpl.select(SelectorImpl.java:141)
at com.esotericsoftware.kryonet.Client.update(Client.java:244)
at com.esotericsoftware.kryonet.Client.run(Client.java:356)
at java.base/java.lang.Thread.run(Thread.java:832)
Without client.dispose()
No Exception logged, but also nothing mentioning that the Client was disconnected.
Server-side
In both cases, while the logs differed on the client-side, the server-side always mentioned how the Client had disconnected.
I'm not sure what to think of this.
EDIT
I tested with a simple Listener and then with a ThreadedListener. I get the same behavior in terms of logging, however, the simple Listener hangs for much less time.
this.client = new Client();
Register.registerClasses(client);
this.addr = isLocalServer
? InetAddress.getLocalHost()
: InetAddress.getByName(REMOTE_SERVER);
// client.addListener(new Listener.ThreadedListener(onReceiveCallback));
client.addListener(onReceiveCallback);
client.start();
client.connect(TIMEOUT, addr, PORT);
It looks like it's related to commit a7e9661 Fixed deadlock in EndPoint#close(). When I rolled that back it got working immediately. No more delays.
+1
I've been experiencing this on the client side too (I don't close the server nearly as often nor the same way, I just kill it, so I don't know if the same problem happens server side).
