Hang on reconnectBlocking

[Xander-Polishchuk]

Describe the bug
Sometime WebSocketClient hangs on reconnectBlocking() at WebSocketClient.java:422 on closeLatch.await(). That happens very occasionally.

To Reproduce
Steps to reproduce the behavior:

1. Setup server and client
2. Connect to Server
3. call reconnectBlocking() in a loop

Expected behavior
reconnectBlocking() should never hang

Debug log
The only log:

11:36:42.216 [WebSocketConnectReadThread-5820] TRACE org.java_websocket.WebSocketImpl -- write(171): GET / HTTP/1.1
Connection: Upgrade
Host: localhost:41516
Sec-WebSocket-Key: HGF5XrGAw3IBiWJKCnLPTA==
Sec-WebSocket-Version: 13
Upgrade: websocket


11:36:42.222 [WebSocketConnectReadThread-5820] TRACE org.java_websocket.WebSocketImpl -- process(148): (HTTP/1.1 101 Switching Protocols
Content-Length: 0
Connection: Upgrade
Upgrade: websocket
Sec-WebSocket-Accept: TfhKZHYT6wDgMrIvABVEeUyEBiw=

)
11:36:42.222 [WebSocketConnectReadThread-5820] TRACE o.java_websocket.drafts.Draft_6455 -- acceptHandshakeAsClient - Matching extension found: DefaultExtension
11:36:42.222 [WebSocketConnectReadThread-5820] TRACE o.java_websocket.drafts.Draft_6455 -- acceptHandshake - Matching protocol found: 
11:36:42.222 [WebSocketConnectReadThread-5820] TRACE org.java_websocket.WebSocketImpl -- open using draft: Draft_6455 extension: DefaultExtension protocol:  max frame size: 2147483647
11:36:42.222 [WebSocketConnectReadThread-5820] TRACE o.java_websocket.AbstractWebSocket -- Connection lost timer started

"Test worker@1" prio=5 tid=0x1 nid=NA waiting
  java.lang.Thread.State: WAITING
	  at jdk.internal.misc.Unsafe.park(Unsafe.java:-1)
	  at java.util.concurrent.locks.LockSupport.park(LockSupport.java:211)
	  at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:715)
	  at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1047)
	  at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:230)
	  at org.java_websocket.client.WebSocketClient.closeBlocking(WebSocketClient.java:422)
	  at org.java_websocket.client.WebSocketClient.reset(WebSocketClient.java:343)
	  at org.java_websocket.client.WebSocketClient.reconnectBlocking(WebSocketClient.java:327)

Environment(please complete the following information):

• Version used: 1.5.4
• Java version: 17
• Operating System and version: Windows 10

[PhilipRoman]

Thanks for the detailed bug reports. I will try to take a look, most likely next week as I'm very busy right now.

[nilkanth0018]

Facing same issue while connectBlocking() also,

What happened in my case:

When I try to connect first time using connectBlocking(), 4 out of 5 times it gives an error on WebSocketClient.java class Line No: 515, it is not specific error and also it will not go into the catch block, it just step out the method.

while (!isClosing() && !isClosed() && (readBytes = istream.read(rawbuffer)) != -1) {
        engine.decode(ByteBuffer.wrap(rawbuffer, 0, readBytes));
      }

Then I reconnecting using reconnectBlocking()

So in the reset() method, it stuck at Line No: 343 at closeBlocking(), because closeLatch is awaiting at Line No: 422

One more thing when we shutdown the server at that time it throw error on client side. Utill it will hang on awaiting state.

I am also using
Version : 1.5.4
Java version: Adoptium OpenJDK 17
Operating System and version: Windows 10

Can you please, Help!

[nilkanth0018]

@PhilipRoman any update on this?

[PhilipRoman]

@nilkanth0018
A few days ago I implemented a fix for a closely related issue (see #1367 )
If possible, could you try building the library from branch reconnect-fix and test if this issue occurs for you? It is simple, just run

mvn package -DskipTests=true

And the jar will appear in target directory

[Xander-Polishchuk]

@PhilipRoman Thanks for the fix! I will have a look on this week closer to the end.

[Xander-Polishchuk]

@PhilipRoman sorry for delay, tested with the branch and everything seems working a it should be. I don't observe any hangs or NPE. Thanks you for the fix!

[Xander-Polishchuk]

Hey @PhilipRoman any chance to have a bugfix release with the fix? Thanks!

[PhilipRoman]

@marci4 does the releases