Why Park (Waiting) threads increases ?

Hello Sweta!

 Greetings. Good that you have captured 6 snapshot of threads captured at following time period: 

14:50:19, 14:50:33, 14:50:46, 14:50:59, 14:51:12, 14:51:25 (i.e. gap of 13 seconds). I could see your TIMED_WAITING thread count is increasing. WAITING thread count is staying fairly constant. 

 Your TIMED_WAITING thread count is increasing primarily because of 'default_task' thread group as show in the below screen shot:

 You can see there are 154 threads in TIMED_WAITING state in this 'default_task' thread group. They all have the following stacktrace:

java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000005c1ea32f0> (a org.jboss.threads.EnhancedQueueExecutor)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1421)
at java.lang.Thread.run(Thread.java:748)
Locked ownable synchronizers:
- None

 Basically these threads are originated from the 'org.jboss.threads.EnhancedQueueExecutor'. You might want to check who and why this executor is created? Is there any minimum thread pool size on this executor.