SocketClosed by Listener exception when using samples in high speed loop

[undecided2013]

I converted the TradeClient sample to create random orders in a loop in order to test throughput. I have a Thread.Sleep(ms) in the loop. If the sleep is less than 20ms, the Acceptor Sample does not respond and the tradeclient crashes with a socket closed exception. If I set the sleep to 20ms or higher, the Acceptor and TradeClient work harmoniously together.

Logs have this in them

20200818-13:49:25.641 : Session FIX.4.4:SIMPLE->CLIENT1 already disconnected: Resetting...
20200818-13:49:25.647 : Session reset: New session
20200818-13:49:25.647 : Created session
20200818-13:49:39.559 : FIX.4.4:SIMPLE->CLIENT1 Socket Reader 59817589 accepting session FIX.4.4:SIMPLE->CLIENT1 from 127.0.0.1:58496
20200818-13:49:39.559 : FIX.4.4:SIMPLE->CLIENT1 Acceptor heartbeat set to 0 seconds
20200818-13:49:39.566 : Session FIX.4.4:SIMPLE->CLIENT1 disconnecting: Received msg type 'D' when not logged on
20200818-13:49:39.571 : Session reset: ResetOnDisconnect

Looks like some kind of race condition.