If you are on a UNIX jvm, issue a signal 3 (SIGQUIT) to the jvm process
when tomcat stops responding. It will dump on standard-out (normaly
redirected to catalina.out) the list of Threads with a stacktrace for
each. By invstigating stacktrace you will get clues as where the problem
is. I don't know if mysql is protected against deadlocks, but it may be
user1 locks ressource X, user2 locks ressource Y, user1 wait for Y to
free, user2 wait for X to free, all other users are waiting for X to
free, filling in the ThreadQueue, tomcat then look like unresponsive.
Of course the same kind of concurrency issue can occurs with
synchronized{} blocks
Note, you can also get such dump on windows, it requires you to press
magic key combinaison in JVM terminal (don't remember which)
tc a écrit :
I have been asked to investigate a tomcat/java application.
The basic problem is that this application sometimes becomes unresponsive
if more than one user uses it at a time. Restarting Tomcat clears the
problem. I don't think it has ever occurred when only one person was
using the app.
It is a fairly straight forward data-entry app; the data is stored in a
mysql database.
The developers think there may some issue with the database. They have
also done multi-user testing without being able to reproduce the problem.
I'm looking for pointers to any resources on the web or elsewhere that can
help me track down the problem, or ideas about where to look, or what we
can do to improve post-freeze diagnosis of this problem.
I am also a developer, but I don't have a lot of experience with Java or
Tomcat. I'm trying to bring a fresh perspective to this problem.
Thanks.
---------------------------------------------------------------------
To start a new topic, e-mail: users@tomcat.apache.org
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
---------------------------------------------------------------------
To start a new topic, e-mail: users@tomcat.apache.org
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
