> -----Original Message----- > From: Rainer Jung [mailto:rainer.j...@kippdata.de] > Sent: Friday, May 22, 2009 12:39 PM > To: Tomcat Users List > Subject: Re: Running out of tomcat threads - why many threads in > RUNNABLEstage even with no activity > > [Pantvaidya, Vishwajit] Why are connections idle for a long time not > good? I thought threads when idle take only a little memory and cpu. Are > there any other reasons? > > Because you might want to monitor connections in order to learn how many > threads you need for your load and how things grow or shrink over time. > If you keep connections open an infinite number of time, you'll only > monitor the biggest need since restart, which is often not very > interesting, because it often is artificial (triggered by some > performance slowness you might have a very big connection number created > during a short time).
[Pantvaidya, Vishwajit] Good reason - I think ultimately after some immediate testing to diagnose the outofthread issues, I will use timeouts. > > d. atleast 1 server where no firewall exists has run out of threads > > Concurrency = Load * ResponseTime > > Concurrency: number of requests being processed in parallel > Load: Number of Requests per Second being handled > ResponseTime: Average Response time in seconds. > > So in case you have a performance problem and for a given load your > response time goes up by a factor of ten, the number of connections will > also go up by a factpr of 10. That's most often the reason for d) and > was the reason, why we asked for thread dumps. [Pantvaidya, Vishwajit] Again good explanation and makes a lot of sense - I do seem to remember we had performance problems on that machine. Will keep this in mind and monitor threads and take dumps if outofthreads reoccurs on that server. > > - Bring workers.properties settings in line with Apache recommendations: > > - Worker...cachesize=10 - set to 1 > > respectively when using Apache, remove this. Rely on the defaults for > that one. [Pantvaidya, Vishwajit] Sure will do - once we migrate to jk 1.2.28. > > > - Worker...cache_timeout=600 - remove > > - Worker...recycle_timeout=300 - remove > > Hmmm. [Pantvaidya, Vishwajit] Considering the excellent reasons you have given above - ultimately I will retain timeouts. But for testing firewall issues, I need to rollback connTimeout in server.xml and to make sure that my settings are consistent I need to rollback the above timeouts also. Again thanks - I think I have reasonable explanations for most of the issues / conflicting observations. This thread may be quiet for some time as I do more testing as per the actions I mentioned - will get back with results and final conclusions later. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
