On 25/03/2025 11:24, William Crowell wrote:
Chris,
Looking at JMX is the next step. I make a request and Tomcat never returns,
and I do not get a “connection refused”. It just sits and hangs.
Looking that the thread dump you sent me privately now.
Which port/protocol are you using to connect to Tomcat? HTTP and 8080?
Are you connecting directly to Tomcat or is there a proxy involved at all?
Mark
Regards,
William Crowell
From: Christopher Schultz <ch...@christopherschultz.net>
Date: Tuesday, March 25, 2025 at 7:20 AM
To: users@tomcat.apache.org <users@tomcat.apache.org>
Subject: Re: NIO Thread Madness
William,
On 3/24/25 2:56 PM, William Crowell wrote:
I am running Apache Tomcat 9.0.97 on Windows Server 2022. I’m running Oracle
JDK 1.8.0_371-b11 with a 4GB min heap and a 16GB max heap.
I have an application deployed on this server that is hitting an Oracle
database server. I have noticed the server stops accepting requests after
about 8-12 hours of uptime. In JProfiler you can tell when this is about to
happen because 20 of the 150 NIO threads BRIEFLY…BRIEFLY go into a blocked
state while querying the database. After this situation clears up, the NIO
thread pool grows slightly by about 15-20 threads, and then the application
server stops serving requests.
I looked at the GC log, and it looks completely healthy, and we are not even
close to our max heap. Metaspace size is not configured, but it looks fine
from the GC logs. There is no crash file or core dump produced.
I do notice some Oracle exceptions in the logs when this happens. We do have
about 1000 max connections defined on the Oracle database (which is too many).
Are you able to use JMX or similar to see how many used database
connections you have?
When you say that Tomcat does not accept requests, do you mean that you
make a request and it never returns, or do you mean that you get a
"connection refused" or something similar?
I have my thread pool defined as follows in server.xml:
…
<Executor name="tomcatThreadPool"
namePrefix="catalina-exec-"
maxThreads="1000"
minSpareThreads="50"
maxIdleTime="60000"
maxQueueSize="1000" />
<Connector port="8080"
protocol="org.apache.coyote.http11.Http11NioProtocol"
connectionTimeout="130000"
redirectPort="8443"
disableUploadTimeout="false"
acceptCount="1000"
maxConnections="1000"
executor="tomcatThreadPool" />
Have you tried enabling any of the "abandoned"-related settings? I
highly recommend logAbandoned="true" and possibly others.
I would imagine you'd see threads waiting on database connections if you
had exhausted your pool. Just remember that threads can be stuck on
things without being BLOCKED.
> Are there any logs I can enable to find out why the application
server stops accepting connections?
-chris
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