Tomcat doesn't stop. How can I debug this?
Solution 1
If the web application is stopped, all connections to the database should be closed as well. If you don't have a list of connections, then execute the SQL statement "shutdown" (this only works for the H2 and HSQLDB databases).
If you have a registered a Servlet, you can do that in the Servlet.destroy()
method.
If you have registered a ServletContextListener
, you can execute the "shutdown" statement in the ServletContextListener.contextDestroyed(ServletContextEvent servletContextEvent)
method. This is what org.h2.server.web.DbStarter
ServletContextListener
does (the one that is included in the H2 database).
Solution 2
Find out what threads are still running (or blocked, waiting to run) by using jstack or sending a signal to the process:
kill -3 pid
When you know this, you can make whatever it was that started them hook into the shutdown notification to stop the threads. Or make those threads deamon threads.
See This tomcat shutdown question for more details on this.
If you don't know where your threads were created, then consider adding names to them - executors can take thread factories, and you can use those factories to set the deamon status of a thread and also to name it - so your stack trace will be clearer.
Solution 3
Check if your Web Application has some Scheduler active, like Quartz.
If you don't stop it, Web Application Thread never ending until you kill it
Solution 4
I had the exact same problem. Sometimes, the command ./shutdown.sh
does not stop the tomcat process, and its java
process stays in the running processes.
I had solved this problem using the Tomcat version in the Ubuntu's software repositories, by:
sudo apt-get install tomcat7
After installing it from package manager and configuring some settings, I did not have any problems on stopping/starting Tomcat. I used this command to stop, and it never failed:
service tomcat7 stop
which is nearly the same as
/etc/init.d/tomcat7 stop
Using this command runs the code block from the init script, specifically, the codes from the file /etc/init.d/tomcat7
. So I looked into it to see what it does to always kill the tomcat process succesfully. Here is the code block that runs when you use service tomcat7 stop
command:
log_daemon_msg "Stopping $DESC" "$NAME"
set +e
if [ -f "$CATALINA_PID" ]; then
start-stop-daemon --stop --pidfile "$CATALINA_PID" \
--user "$TOMCAT7_USER" \
--retry=TERM/20/KILL/5 >/dev/null
if [ $? -eq 1 ]; then
log_progress_msg "$DESC is not running but pid file exists, cleaning up"
elif [ $? -eq 3 ]; then
PID="`cat $CATALINA_PID`"
log_failure_msg "Failed to stop $NAME (pid $PID)"
exit 1
fi
rm -f "$CATALINA_PID"
rm -rf "$JVM_TMP"
else
log_progress_msg "(not running)"
fi
log_end_msg 0
set -e
;;
The important part is this:
start-stop-daemon --stop --pidfile "$CATALINA_PID" \
--user "$TOMCAT7_USER" \
--retry=TERM/20/KILL/5 >/dev/null
This means "retry stopping until the process is stopped. Here is the --retry command documentation from start-stop-daemon manual:
-R|--retry timeout|schedule With --stop, specifies that start-stop-daemon is to check whether the process(es) do finish. It will check repeatedly whether any matching processes are running, until none are. If the processes do not exit it will then take further action as determined by the schedule. If timeout is specified instead of schedule then the schedule signal/timeout/KILL/timeout is used, where signal is the signal specified with --signal. ...
So, --retry=TERM/20/KILL/5
means "Send TERM signal to the process, wait 20 seconds, if it's still running, send KILL signal, wait 5 seconds, if it's still running, there is a problem.
This means you can configure the tomcat to run as a deamon and use a command like this, or write a script to do that kind of action to stop tomcat, or just use Ubuntu and get the tomcat from the package manager.
Solution 5
I also had the same problem. There was a ThrottledThreadPoolExecutor in my application that wasn't getting shutdown. When I shut it down properly, tomcat would stop cleanly. In order to figure out the problem, I had to remove all the apps from my tomcat webapps
directory and then add them one by one and see which one was causing the problem
Jim
Updated on August 03, 2020Comments
-
Jim almost 4 years
I have a
Tomcat 7
running in Linux that I start via$CATALINA_HOME/bin/startup.sh
and shutdown via$CATALINA_HOME/bin/shutdown.sh
from/etc/init.d
All is ok except 1 problem. Sometimes tomcat does not stop.
Although I stop it and I see in catalina.out logs that is going down, if I dops -ef
I can still see the process running.What could be the problem? How can I debug this? My feeling is, that this is related to threads.
So the parts that are suspicious are the following:
1) I use Log4j's LogManager to detect if the log4j configuration has been changed, but I doLog4jManager.shutdown
on acontextDestroyed
ServletContextListener
2) I useH2
database and I see on shutdown:SEVERE: The web application [/MyApplication] appears to have started a
thread named [H2 Log Writer MYAPPLICATION] but has failed to stop it.
This is very likely to create a memory leakSEVERE: The web application [/MyApplication] appears to have started a
thread named [H2 File Lock Watchdog
/opt/myOrg/tomcat/webapps/MyApplication/db/myDatabase.lock.db] but has
failed to stop it. This is very likely to create a memory leak. Apr 2,
2012 9:08:08 AM org.apache.catalina.loader.WebappClassLoader
clearReferencesThreads SEVERE: The web application [/MyApplication]
appears to have started a thread named [FileWatchdog] but has failed
to stop it. This is very likely to create a memory leak.Any help please? How can I detect the problem here?
UPDATE:
I did akill -3
as suggested by @daveb, and in the catalina.out I see:JVMDUMP006I Processing dump event "user", detail "" - please wait. JVMDUMP032I JVM requested Java dump using '/etc/init.d/javacore.20120402.093922.2568.0001.txt' in response to an event JVMDUMP010I Java dump written to /etc/init.d/javacore.20120402.093922.2568.0001.txt JVMDUMP013I Processed dump event "user", detail "".
There is a javacore in
/etc/init.d
but I don't know how to process it. I.e. what parts should I investigate -
daveb about 12 yearsOpen the javacore .txt file in a text editor, look for thread stacks that include packages that you've written.
-
Jim about 12 yearsYes I figured that.But I am not sure on what indicates an error.
-
Jim about 12 yearsThanks for the reply!
If the web application is stopped, all connections to the database should be closed as well
. I am using Tomcat's connection pool. So it is out of my hands.Is this a known 'racing' issue between Tomcat and H2.I can doSHUTDOWN
(it is safe right?) but I want to make sure I address this correctly -
Thomas Mueller about 12 yearsIt see the problem. Not sure what the best solution is... ignore the exception? The statement
SHUTDOWN
will only close this database, so it should be relatively save - only if you are not sure if other web apps are using the database, then you can't do that. Another solution is to use the server mode (run the H2 database in another process). -
Jim about 12 years:No the database is mine i.e. no other applications will access it.And I am required to use it in file mode.So basically you are saying that 1) shutdown is safe for the data 2)I can ignore the exception meaning what?That Tomcat does not hang on shutdown because of H2 still running?I see the
db.lock
file in the directory of my app -
Thomas Mueller about 12 yearsThe
<databaseName>.lock.db
file is not deleted as long as the database is open. The database is open because there is at least one open connection. There is at least one open connection because the connection pool is not disposed. If you executeshutdown
then the database is closed. In your case, that is save. -
Vicky over 7 yearsIn my case i have to stop all the connection including quartz thread when tomact stops.Even i have ServletContextListener.contextDestroyed method but i dont know how to stop all connections when tomcat stops
-
hello_earth over 3 yearsthere's also this useful thread: serverfault.com/questions/1021145/…. and oh my was I so sure that I was spawning no threads of mine - and yet I really did, I just forgot. I was so sure that I was searching for old bug reports on legacy iBatis that we are using, thinking that it was the culprit - not cleaning up connections and such. was I so wrong.