atom feed10 messages in org.apache.tomcat.usersExpected behavior of Tomcat under load
FromSent OnAttachments
Asankha C. PereraMay 25, 2011 4:51 am 
Peter CrowtherMay 25, 2011 6:53 am 
Asankha PereraMay 26, 2011 8:56 am 
André WarnierMay 26, 2011 9:04 am 
Caldarale, Charles RMay 26, 2011 9:09 am 
Asankha C. PereraMay 26, 2011 9:12 am 
Caldarale, Charles RMay 26, 2011 9:16 am 
André WarnierMay 26, 2011 9:19 am 
Asankha C. PereraMay 26, 2011 10:34 am 
André WarnierMay 26, 2011 10:55 am 
Subject:Expected behavior of Tomcat under load
From:Asankha C. Perera (asan@apache.org)
Date:May 25, 2011 4:51:08 am
List:org.apache.tomcat.users

Hi All

During some performance tests, we've seen that Tomcat resets TCP connections under high load. To reproduce this rather consistently, a thread pool with a maximum of 300 threads could be configured on default Tomcat 6.0.32, and then 1280 ~ 2560 concurrent user requests simulated from a different machine over a real NW interface. I assume this could be reproduced with proportionately smaller numbers for both as well. The implementation uses a Xfire soap service.

Tomcat refusing connections, or taking longer to accept new connections, or taking longer to reply (causing a socket timeout) can be expected under such load - but what we see are TCP resets of connections to which a client has already sent a full HTTP request.

Is this the default behavior of Tomcat? The problem this presents is that the client cannot safely fail over to another instance, unlike with a refused connection or a connect timeout (i.e. delay in accepting)

thanks asankha

No. Time Source Destination Protocol Src Port Dst Port Info 389961 37.056567 10.77.69.8 10.101.29.42 TCP 9062 8080 9062 > 8080 [SYN] Seq=0 Win=5792 [TCP CHECKSUM INCORRECT] Len=0 MSS=1460 TSV=363753 TSER=363574 WS=7 391297 37.108766 10.101.29.42 10.77.69.8 TCP 8080 9062 8080 > 9062 [SYN, ACK] Seq=0 Ack=1 Win=5792 Len=0 MSS=1460 TSV=363383 TSER=363753 WS=7 391298 37.108773 10.77.69.8 10.101.29.42 TCP 9062 8080 9062 > 8080 [ACK] Seq=1 Ack=1 Win=5888 [TCP CHECKSUM INCORRECT] Len=0 TSV=363758 TSER=363383 391893 37.115809 10.77.69.8 10.101.29.42 HTTP 9062 8080 POST /xfire/xfire-service HTTP/1.1 391894 37.115837 10.77.69.8 10.101.29.42 HTTP 9062 8080 Continuation or non-HTTP traffic[Packet size limited during capture] 392677 37.125492 10.101.29.42 10.77.69.8 TCP 8080 9062 8080 > 9062 [RST] Seq=1 Win=0 Len=0

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