Can you share the configuration of the connection pool? Don't forget to mask any passwords.
Mark On 19/01/2020 05:43, Jerry Malcolm wrote: > I have a web page that makes a couple of hundred ajax calls when it > loads. But the calls are recursive. The response from one call > generates a couple of more calls. The responses from those calls > generate others, etc. So this is not a blast of 200 simultaneous calls > to the server. In most cases the count of active database connections > never gets over 10-15 at a time. I have the max count on the connection > pool set to 125. > > The server has very low traffic averaging a few pages an hour. > Yesterday, I was testing this one page described above and and I started > getting errors that no connections were available in the pool. My > connection abort timeouts are very short, about 5 seconds, and the wait > time for a free connection is 60 seconds, I believe. So theoretically, > even if there were connection leaks, they should be returned well before > waiting connections timed out, right? I went to the AWS RDS console to > look at the connections graph. It showed that in the previous couple of > minutes the database went from 3 connections to the max of 125. The > page had timeout errors. But it was done. There was no more activity > on this webapp. Yet the database monitor continued to show 125 > connections. I kept refreshing for about 10 minutes expecting the > connection pool to finally drop all of the connections. Nothing. > Finally after about 10 minutes it still showed 125 connections, I > bounced tomcat and the connection count on the database immediately fell > to zero. BTW, I have logAbandoned set to true, and I'm not getting any > abandon log entries. > > The problem occurred twice requiring a reboot of TC each time. I > enabled some jmx code in my web app that logs the connection count each > time I request/return a connection. Of course, now that I've got > logging on, I can't reproduce the problem. I can reload that page a > hundred times now, and my AWS RDS monitor shows a bump up to 10-15 > connections for a brief time, then returns, exactly like I believe it > should be working. > > I'm not a big fan of problems that just go away. I really want to > figure out what is happening here, even if it's random. I don't > believe this is a problem in the mainline code. Otherwise I think it > would be more consistent. And again, even if I was not returning > connections, they should be timing out and being logged. Another option > is that I have a rogue thread that is sucking up all of the connections > and holding them. But this problem only starts when I load this page. > And I'm not aware of code that starts new threads in that area. Is > there anything I can be doing to the connection pool to make it not > close connections and return them to the pool? Or is there anything the > database could be doing that would cause closing a connection to fail? > > I guess I'm just grasping at straws. Is there any type of low-level > logging that I can enable that will tell me each time a connection is > requested and returned (and possibly the call stack each time)? > > I've got a feeling this one is going to bite me some time soon and take > a client site down with it. I really need to understand this one. > > Thanks as always, > > Jerry > > > --------------------------------------------------------------------- > 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
