Thank you Chris for your response. On Wed, Nov 11, 2020 at 10:02 PM Christopher Schultz <ch...@christopherschultz.net> wrote: > > Suvendu, > > On 11/11/20 06:40, Suvendu Sekhar Mondal wrote: > > Application Setup: > > AdoptOpenJDK 1.8.192, Tomcat 7.0.55, Apache httpd, Windows 2012, SQL Server > > 2016 > > As Michael pointed-out, these all need to be upgraded, but they are not > affecting your experience, here. > > > Observations: > > After database failover, we noticed that HTTP thread pool size jumped > > from 10 to 50. No. of busy threads jumped to 40 for a minute and then > > came down to normal range(1-5). But thread pool size remained 50 for > > the next one hour. When we collected the heap dump after one hour, > > thread pool size jumped again to ~90. Thread dump analysis is showing > > most of the HTTP threads were just waiting to get some work[1]. That > > looked surprising to me. Few of them are runnable and doing some work > > - which matches "busy thread" count. During all this timeframe load on > > the system remained the same. > > > > We have 30sec connectionTimeout. Also TTL is set to 300 in httpd. We > > do not have any keepAliveTimeout set in Tomcat. App uses session > > affinity. We were looking for some connector properties which deal > > with idle threads but found none[3]. > > You won't find them. > Okay. > > We are not seeing any "problem" in our app after DB failover but this > > is something also newer to us and we are trying to explain it. > > What are you trying to explain? > We are simply trying to understand this behavior as this is something new we noticed. > > Tomcat's memory usage increased by a few MB as new threads were > > spawned. My expectation was that if threads in the thread pool are not > > getting used and idle, after sometime thread pool size will reduce to > > "minSpareThreads" size which is 10 in our case. Is that expectation > > wrong? Can you please share your thoughts? > > This is a common misconception. If you do not configure an "executor" > then Tomcat will create one for you and it will NOT remove idle threads > from the thread pool. > > The solution is to manually-specify an Executor: > > <Executor name="myExecutor" namePrefix="myExecutor-" maxThreads="X" > minSpareThreads="Y" /> > > <Connector executor="myExecutor" ... /> > > With this configuration, you should see your thread count stay between Y > and X, but when X are not necessary, your thread count should drop > towards Y as appropriate. >
Thanks for the explanation. This is the kind of information I was looking for in Tomcat docs but was not able to locate it. We will try this approach and let you know the outcome. > Hope that helps, > -chris > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
