@Vivian Wilfred​  Previously 20 jobs were running on one worker node. Now I reduced number of the jobs to 9 and increased the number of workers to 5. I am not getting the REPL error now. But I am getting TimeoutException: Futures timed out after [5 seconds] error and Fatal error: The Python kernel is unresponsive error. I was getting these error in my previous run too. REPL is resolved.