For concurrency

1.　Operating Environment
JBoss EAP 7, RHEL 7.1

2.　Our requests
Current conditions:
・The web application was deployed on the JBoss.
・The client program sent GET requests about 150 times within five seconds.
・The elapsed time from the first request to the last request recorded in the log file was about 50 seconds. The elapased time was much longer than our requirement.
・Observing the log file, the first fifteen requests were accepted within two seconds. Acceptances of other requests consumed long time.

Our requests:
We guessed that the first fifteen requests were buffered quickly until a Jboss internal FIFO was full and other requests were accepted slowly only when a preceding request was retrieved from the FIFO and an empty position was created in the FIFO.
Do you have any idea about the cause of delay of acceptance after the first fifteen requests were accepted? And how can we improve the acceptance speed in the case that more than 100 requests are sent within five seconds?

・Current situation overview
2016/7/14 21:00:00 Request #1 was accepted.
2016/7/14 21:00:00 Request #2 was accepted.
・・・
2016/7/14 21:00:02 Request #15 was accepted.
・・・
2016/7/14 21:00:10 Request #20 was accepted.
・・・
2016/7/14 21:00:50 Request #150 was accepted.

・Preferred situation
2016/7/14 21:00:00 Request #1 was accepted.
2016/7/14 21:00:00 Request #2 was accepted.
・・・
2016/7/14 21:00:02 Request #15 was accepted.
・・・
2016/7/14 21:00:02 Request #20 was accepted.
・・・
2016/7/14 21:00:05 Request #150 was accepted.

Thanks and Best Regards,