AssertionError at WebSocketImpl.isOpen

[PhilipRoman]

Expected Behavior

WebSocketImpl.isOpen() returns true if the socket is open and false otherwise.

Current Behavior

Calling isOpen() on a websocket causes and AssertionError. Here is the assertion causing it:
assert ( getReadyState() != READYSTATE.OPEN || !flushandclosestate )
It is not entirely clear why such a method would ever throw an exception. There are 2 possible stacktraces which appear randomly:

Exception in thread "WebSocketSelector-15" java.lang.AssertionError
	at org.java_websocket.WebSocketImpl.isOpen(WebSocketImpl.java:720)
	at com.mypackage.ClientConnection.send(ClientConnection.java:130)
	[Bussiness logic frames here...]
	at com.mypackage.Cluster.onClose(Cluster.java:114)
	at org.java_websocket.server.WebSocketServer.onWebsocketClose(WebSocketServer.java:595)
	at org.java_websocket.WebSocketImpl.closeConnection(WebSocketImpl.java:504)
	at org.java_websocket.WebSocketImpl.closeConnection(WebSocketImpl.java:522)
	at org.java_websocket.SocketChannelIOHelper.batch(SocketChannelIOHelper.java:99)
	at org.java_websocket.server.WebSocketServer.run(WebSocketServer.java:428)
	at java.base/java.lang.Thread.run(Thread.java:844)

Uncaught exception in thread "WebSocketWorker-14":java.lang.AssertionError
	at org.java_websocket.WebSocketImpl.decode(WebSocketImpl.java:225)
	at org.java_websocket.server.WebSocketServer$WebSocketWorker.run(WebSocketServer.java:906)

Steps to Reproduce (for bugs)

I'll make a minimal program to reproduce it and other info unless it turns out to be a mistake from my own code. The bug is hard to reproduce reliably.
Here is a brief outline of how I get the bug:

final Cluster cluster = new Cluster(20); // subclass of WebSocketServer
final int clientCount = 20;
Executor executor = Executors.newCachedThreadPool();
cluster.start();
for (int i = 0; i < 10; i++) {
	int port = cluster.getPort();
	Collection<MockClient> clients = Stream.generate(() -> new MockClient(port))
		.limit(clientCount)
		.collect(Collectors.toCollection(() -> new ArrayList<>(clientCount)));
	clients.forEach(executor::execute);
	sleep(2000);
	clients.forEach(WebSocketClient::close);
	sleep(2000);
}

[marci4]

Hello @PhilipRoman,

thank you very much for your bug report!

Yeah you are right, such a method should not contain an assert.

I think the best solution is to just remove them!

Best regards,
marci4

[marci4]

Issue is fixed by PR #702.

Thank you again, @PhilipRoman.

Best regards,
marci4