Canceling a spark job using barrier mode but barrier tasks do not exit

import time
from pyspark import BarrierTaskContext

n = 4

def  task(x):
  context = BarrierTaskContext.get()
  this = next(x)
  if (this % 2 == 0):
    time.sleep(10000)
  context.barrier()
  return []

sc.setLogLevel("INFO")
sc.parallelize(list(range(n)), n).barrier().mapPartitions(task).collect()

19/02/05 01:07:42 INFO BarrierTaskContext: Task 3 from Stage 0(Attempt 0) has entered the global sync, current barrier epoch is 0.
19/02/05 01:07:42 INFO BarrierTaskContext: Task 1 from Stage 0(Attempt 0) has entered the global sync, current barrier epoch is 0.
19/02/05 01:07:47 INFO Executor: Executor is trying to kill task 2.0 in stage 0.0 (TID 2), reason: Stage cancelled
19/02/05 01:07:47 INFO Executor: Executor is trying to kill task 0.0 in stage 0.0 (TID 0), reason: Stage cancelled
19/02/05 01:07:47 INFO Executor: Executor is trying to kill task 1.0 in stage 0.0 (TID 1), reason: Stage cancelled
19/02/05 01:07:47 INFO Executor: Executor is trying to kill task 3.0 in stage 0.0 (TID 3), reason: Stage cancelled
19/02/05 01:07:50 WARN PythonRunner: Incomplete task 0.0 in stage 0 (TID 0) interrupted: Attempting to kill Python Worker
19/02/05 01:07:50 INFO Executor: Executor killed task 0.0 in stage 0.0 (TID 0), reason: Stage cancelled
19/02/05 01:07:50 WARN PythonRunner: Incomplete task 3.3 in stage 0 (TID 3) interrupted: Attempting to kill Python Worker
19/02/05 01:07:50 INFO Executor: Executor killed task 3.0 in stage 0.0 (TID 3), reason: Stage cancelled
19/02/05 01:07:50 WARN PythonRunner: Incomplete task 2.2 in stage 0 (TID 2) interrupted: Attempting to kill Python Worker
19/02/05 01:07:50 INFO Executor: Executor killed task 2.0 in stage 0.0 (TID 2), reason: Stage cancelled
19/02/05 01:07:50 WARN PythonRunner: Incomplete task 1.1 in stage 0 (TID 1) interrupted: Attempting to kill Python Worker
19/02/05 01:07:50 INFO Executor: Executor killed task 1.0 in stage 0.0 (TID 1), reason: Stage cancelled
19/02/05 01:08:42 INFO BarrierTaskContext: Task 3 from Stage 0(Attempt 0) waiting under the global sync since 1549328862443, has been waiting for 60 seconds, current barrier epoch is 0.
19/02/05 01:08:42 INFO BarrierTaskContext: Task 1 from Stage 0(Attempt 0) waiting under the global sync since 1549328862522, has been waiting for 60 seconds, current barrier epoch is 0.
19/02/05 01:09:42 INFO BarrierTaskContext: Task 3 from Stage 0(Attempt 0) waiting under the global sync since 1549328862443, has been waiting for 120 seconds, current barrier epoch is 0.
19/02/05 01:09:42 INFO BarrierTaskContext: Task 1 from Stage 0(Attempt 0) waiting under the global sync since 1549328862522, has been waiting for 120 seconds, current barrier epoch is 0.
19/02/05 01:10:42 INFO BarrierTaskContext: Task 3 from Stage 0(Attempt 0) waiting under the global sync since 1549328862443, has been waiting for 180 seconds, current barrier epoch is 0.
19/02/05 01:10:42 INFO BarrierTaskContext: Task 1 from Stage 0(Attempt 0) waiting under the global sync since 1549328862522, has been waiting for 180 seconds, current barrier epoch is 0.
19/02/05 01:11:42 INFO BarrierTaskContext: Task 3 from Stage 0(Attempt 0) waiting under the global sync since 1549328862443, has been waiting for 240 seconds, current barrier epoch is 0.
19/02/05 01:11:42 INFO BarrierTaskContext: Task 1 from Stage 0(Attempt 0) waiting under the global sync since 1549328862522, has been waiting for 240 seconds, current barrier epoch is 0.