Hi Chuck, > -----Original Message----- > From: Chuck Caldarale <n82...@gmail.com> > Sent: Sunday, May 26, 2024 2:21 PM > To: Tomcat Users List <users@tomcat.apache.org> > Subject: Re: Database Connection Requests Initiated but Not Sent on the Wire > (Some, Not All) > > > > On May 25, 2024, at 20:58, Eric Robinson <eric.robin...@psmnv.com> wrote: > > > > One of our hosting customers is a medical practice using a commercial EMR > running on tomcat+mysql. It has operated well for over a year, but users have > suddenly begun experiencing slowness for about an hour at the same time > every day. During the slow times, we've done all the usual troubleshooting to > catch the problem in the act. The servers have plenty of power and are not > overworked. There are no slow database queries. Network connectivity is solid. > Tomcat has plenty of memory. The numbers of database connections, threads, > questions, queries, etc., remain steady, without spikes. There is no unusual > disk > latency. We have not found any maintenance tasks running during that > timeframe. > > > <snip/> > > > > There are no unusual errors in the tomcat or database server logs, EXCEPT > this one: Java.sql.DriverManager.getConnection > > > <snip/> > > > > During the periods of slowness, we see lots of those errors along with a > > large > spike in the number of stuck tomcat threads (from 1 or 2 to as high as 100). > It > seems obvious that the threads are stuck because tomcat is waiting on a > connection to the database. > > > <snip/> > > > > We are forced to conclude that some database connection requests are being > initiated but are not being sent on the wire. > > > Could the DB server be out of ports? (Seems unlikely, based on your debugging > so far.) >
We have not seen any indication of that. > Any chance that the Tomcat process is running out of file descriptors? Or > ports? > Likewise, no indications of that. > Can you force a garbage collection (e.g., with jconsole or similar tool) > during a > slow period? If there is some limit on an OS-level resource that’s being > reached, > a GC may be able to delete the Java objects that are tying up the underlying > resources. GC is on my list of things to try. > > - Chuck > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org Disclaimer : This email and any files transmitted with it are confidential and intended solely for intended recipients. If you are not the named addressee you should not disseminate, distribute, copy or alter this email. Any views or opinions presented in this email are solely those of the author and might not represent those of Physician Select Management. Warning: Although Physician Select Management has taken reasonable precautions to ensure no viruses are present in this email, the company cannot accept responsibility for any loss or damage arising from the use of this email or attachments.
