> The clients timeout because they spend more than timeout in the > acceptCount/backlog queue waiting for Tomcat to call Socket.accept()
Ok, so you are stating, that clients timeout while their requests are in the acceptCount/backlog. This is not what I am seeing. See below. > So we have: > maxThreads=4 > maxConnections=10 > acceptCount=20 > > and a request processing time of 1 second. > > I'd guess that the OS is using a much large accept count. Let's model it. > > 0s - 50 connections in acceptCount > 1s - 39 connections in acceptCount, 11 connections maintained by Tomcat, > 4 requests processing > 2s - 35 connections in acceptCount, 11 connections maintained by Tomcat, > 4 requests processing, 4 completed requests 3s - 31 connections in > acceptCount, 11 connections maintained by Tomcat, > 4 requests processing, 8 completed requests 4s - 27 connections in > acceptCount, 11 connections maintained by Tomcat, > 4 requests processing, 12 completed requests 5s - 23 connections in > acceptCount, 11 connections maintained by Tomcat, > 4 requests processing, 16 completed requests 6s - 19 connections timed > out, 11 connections maintained by Tomcat, > 4 requests processing, 20 completed requests 7s - 19 connections timed > out, 7 connections maintained by Tomcat, > 4 requests processing, 24 completed requests 8s - 19 connections timed > out, 3 connections maintained by Tomcat, > 3 requests processing, 28 completed requests 9s - 19 connections timed > out, 0 connections maintained by Tomcat, > 0 requests processing, 31 completed requests > > That seems to match what you observed. That suggests the OS is using an > acceptCount of at least 50. I can see what you mean, but this is not what I see, because your assumption of a 1s processing time is wrong. The processing time of each request is 10s (thanks to a 10s sleep, which blocks the Thread). So here is what I see instead (note I don't guess the response time, but do actually see/measure it): 0s - 4 requests processing, 11 connections maintained, 20 connections in acceptCount, 19 not in acceptCount 5s - 4 requests processing, 11 connections maintained, 20 connections in acceptCount, 0 not in acceptCount, 19 timed-out 10s - 4 requests processing, 11 connections maintained, 16 connections in acceptCount, 0 not in acceptCount, 19 timed-out, 4 requests processed 20s - 4 requests processing, 11 connections maintained, 12 connections in acceptCount, 0 not in acceptCount, 19 timed-out, 8 requests processed 30s - 4 requests processing, 11 connections maintained, 8 connections in acceptCount, 0 not in acceptCount, 19 timed-out, 12 requests processed 40s - 4 requests processing, 11 connections maintained, 4 connections in acceptCount, 0 not in acceptCount, 19 timed-out, 16 requests processed 50s - 4 requests processing, 11 connections maintained, 0 connections in acceptCount, 0 not in acceptCount, 19 timed-out, 20 requests processed 60s - 4 requests processing, 7 connections maintained, 0 connections in acceptCount, 0 not in acceptCount, 19 timed-out, 24 requests processed 70s - 3 requests processing, 3 connections maintained, 0 connections in acceptCount, 0 not in acceptCount, 19 timed-out, 28 requests processed 80s - 0 requests processing, 0 connections maintained, 0 connections in acceptCount, 0 not in acceptCount, 19 timed-out, 31 requests processed The interesting thing to note is, that contrary to your statement, I don't see timeouts for requests in the acceptCount/backlog. To verify my interpretation, I increased the acceptCount and I saw that the time outs decrease by the same number. I decreased the acceptCount and saw that the time outs increase. The behaviour seems 100% predictable to me... just not as expected based on the documentation. > Not up to Tomcat. Tomcat can only call Socket.accept() and does so under > the control of maxConnections. > > Connection refused == acceptCount/backlog full (or no listening socket). > > Connection refusal is entirely under the control of the OS and will be driven > largely by the actual value of acceptCount/backlog. So if it is not up to Tomcat, then the documentation "Any further simultaneous requests will receive "connection refused" errors" is clearly wrong, isn't it? ________________________________ Pflichtangaben anzeigen<http://www.deutschebahn.com/pflichtangaben/20210430> Nähere Informationen zur Datenverarbeitung im DB-Konzern finden Sie hier: http://www.deutschebahn.com/de/konzern/datenschutz --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
