trying to send message after a user has submitted HIT

[alicexigao]

I've observed this intermittently when I was running my experiment.

Sometimes, right after a worker submits the HIT and disconnects, there will be an exception message, which seems to indicate that the server was trying to send a message after the worker has already disconnected.

Stack trace for two separate instances below:

2979277 [TurkHITController] INFO TurkHITController - Created 421 HITs
3015033 [qtp1398211332-175] INFO GroupServer - 342 HITs completed
3015033 [qtp1398211332-175] INFO GroupServer - 328 HITs submitted
3018467 [qtp1398211332-175] INFO GroupServer - Session dfoxp9t75bsar1m5pd8hawm7wn disconnected
3018467 [qtp1398211332-175] INFO Experiments - A2FJR14DVBT2A3 @ HIT 2QQJHSTLB3L0451FSF2JJJRFCU1HT7 not in experiment, ignoring disconnect callback
3018468 [pool-5-thread-6] WARN org.cometd.websocket.server.WebSocketTransport -
java.io.IOException: closedOut 1001:null
at org.eclipse.jetty.websocket.WebSocketConnectionRFC6455$WSFrameConnection.sendMessage(WebSocketConnectionRFC6455.java:437)
at org.cometd.websocket.server.WebSocketTransport.send(WebSocketTransport.java:244)
at org.cometd.websocket.server.WebSocketTransport.send(WebSocketTransport.java:238)
at org.cometd.websocket.server.WebSocketTransport$WebSocketScheduler.schedule(WebSocketTransport.java:555)
at org.cometd.websocket.server.WebSocketTransport$WebSocketScheduler.run(WebSocketTransport.java:469)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)

96167180 [pool-4-thread-1] INFO GroupServer - 364 HITs submitted
96221654 [TurkHITController] INFO TurkHITController - Created 485 HITs
96253389 [qtp696141169-1726] INFO GroupServer - 381 HITs completed
96253389 [qtp696141169-1726] INFO GroupServer - 365 HITs submitted
96256009 [qtp696141169-1726] INFO GroupServer - Session 4jq1wviq5rlfzin30te1v5k8hz disconnected
96256009 [qtp696141169-1726] INFO Experiments - A1FMVC76BUNVPQ @ HIT 248YN5F3Q0JGUNGSX3NYG49GQAOFBL not in experiment, ignoring disconnect callback
96282369 [TurkHITController] INFO TurkHITController - Created 486 HITs
96300528 [qtp696141169-1726] INFO GroupServer - 381 HITs completed
96300528 [qtp696141169-1726] INFO GroupServer - 366 HITs submitted
96305163 [qtp696141169-1726] INFO GroupServer - Session 4d13lpbowky2fl31q7xshcd2dzh3 disconnected
96305163 [qtp696141169-1726] INFO Experiments - A1X3QACSVCLWMD @ HIT 2I8P6AUC26DGV1V77UM0KK0D52YA3C not in experiment, ignoring disconnect callback
96309115 [qtp696141169-1728] INFO GroupServer - 381 HITs completed
96309115 [qtp696141169-1728] INFO GroupServer - 367 HITs submitted
96311547 [qtp696141169-1728] INFO GroupServer - Session 4h18jm5gcp0p0lp7f1vjzz64llp disconnected
96311547 [qtp696141169-1728] INFO Experiments - A34YWEDVDZK3SN @ HIT 2C2I62NJQ217RTRF08XBPLCWVTQVNE not in experiment, ignoring disconnect callback
96311547 [pool-5-thread-37] WARN org.cometd.websocket.server.WebSocketTransport -
java.io.IOException: closedOut 1001:null
at org.eclipse.jetty.websocket.WebSocketConnectionRFC6455$WSFrameConnection.sendMessage(WebSocketConnectionRFC6455.java:437)
at org.cometd.websocket.server.WebSocketTransport.send(WebSocketTransport.java:244)
at org.cometd.websocket.server.WebSocketTransport.send(WebSocketTransport.java:238)
at org.cometd.websocket.server.WebSocketTransport$WebSocketScheduler.schedule(WebSocketTransport.java:555)
at org.cometd.websocket.server.WebSocketTransport$WebSocketScheduler.run(WebSocketTransport.java:469)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
96343134 [TurkHITController] INFO TurkHITController - Created 487 HITs
96365482 [qtp696141169-1726] INFO GroupServer - 4llilo4e84c2mz9n04os8jpdlv - last connect 0 ms ago
96365482 [qtp696141169-1726] INFO org.cometd.server.ext.AcknowledgedMessagesExtension - Enabled message acknowledgement for client 4llilo4e84c2mz9n04os8jpdlv - last connect 0 ms ago
96365580 [qtp696141169-1726] INFO GroupServer - HIT 24SB6BFMFFOYNCB73A6DLESDH9UXKF assignment 214JK63ZVE3HGU20S1H9OL5THK3AZK accepted by A2ICGX21IQ48M9
96365582 [qtp696141169-1726] INFO GroupServer - Worker A2ICGX21IQ48M9 needs to take quiz (HIT 24SB6BFMFFOYNCB73A6DLESDH9UXKF)
96403716 [TurkHITController] INFO TurkHITController - Created 488 HITs
96464455 [TurkHITController] INFO TurkHITController - Created 489 HITs
96525073 [TurkHITController] INFO TurkHITController - Created 490 HITs