You can view status of your Apache Web Server by going to a URL of the kind:
To view the JK Status, go to a URL of the kind:
You can view a lot of useful statistics of Tomcat by looking at its Admin Console:
http://<IP:port>/ > click on status link.
Things to look for here are under the approriate headings JVM, jk-8009 (assuming apache is configured to connect via jk on port 8009), http-8080.
Free Memory – Not sure how this works.
Total Memory – Not sure how this works.
Maximum Memory – this is the maximum amount of memory available to tomcat server, it is the value of the -mx setting in your tomcat startup java command (in catalina.sh). If no mx setting is done, a default value is assumed (which is different for windows and linux)
jk-8009 or http-8080
Here the important things to look at are:
Max threads: 200 Current thread count: 28 Current thread busy: 8
Request count: 19 Error count: 0
Max threads – this is maximum number of threads that tomcat can have to process incoming requests (and its internal functions).
Current thread count – this is total number of threads in tomcat’s threadpool at present. Threads will get garbage collected from this pool. And the pool size can grow to ‘Max threads’ size when necessary.
Currrent thread busy – this is total number of threads that are processing variour requests at present.
Request count – total number of http requests received by tomcat since the time it was started.
You have a performance problem in tomcat when:
Current Thread Count is near about Max Threads. This is a clear indicator that tomcat is receiving more requests faster than it can handle. The default Max Thread setting is 200 which is good enough for most applications, but you can change it here in <TOMCAT_HOME>/conf/server.xml – look for your connector element, here you can change (or add if not present) maxThreads attribute. See http://tomcat.apache.org/tomcat-5.5-doc/config/http.html . But beware, you cannot increase this value indiscrimnately(will affect memory and performance both), the optimum value is based on your hardware, and primarily the number of CPUs you have (more the better for increasing maxThreads). Thumb Rule: Do not change defaults, unless you really have to.
You see Out of Memory Exceptions in your catalina log. See the <TOMCAT_HOME>\logs\catalina.out log file. This is a clear indicator that your application needs more memory than what is available. The min,max memory available can be changed here: <TOMCAT_HOME>\bin\catalina.sh or .bat. You can add a entry like this somewhere (A good place would be immediately before this line: # Set juli LogManager if it is present)
(on linux): JAVA_OPTS=”$JAVA_OPTS -ms256M -mx512M”
(on windows): set JAVA_OPTS=-ms256M -mx512M
You can check lots of important mysql params by going to mysql prompt and typing as follows:
mysql> SHOW VARIABLES;
One of things of interest in the response would be: max_connections. This will tell you how many max concurrent connections are allowed.
You can also find out how many concurrent MySQL connections exist at any point in time by using following command:
mysql> show processlist;
The number of rows in the response is equal to number of connections to MySQL at that time.
The most important thing you need to find out is if you are running out of db connections. This you can find out by using the above mentioned commands i.e show processlist shows equal number of connections as max_connections. If this happens you need to increase the max_connections.. HOW?
Ofcourse check the usual things in your db connection pool, you pool size cannot be greater than max_connection value ofcourse.
How to see Log of DB Queries being executed?
How to find how much time is being spent in execution of each query?
How to find the amount of data(bytes) being returned by each query?