Is there away to take a thread dump from Tomcat? I would like to monitor the threads running in Tomcat at a certain point in time.
Note: I was doing that on Web logic but i don't know how it can be done on Tomcat.
If you use Linux, you can send a kill -3 [pid of your tomcat] and it will dump all current threads in the catalina.out.
There is a simple way to monitor tomcat threads and do a dump.
Start tomcat with the folowing java options :
-Dcom.sun.management.jmxremote.port=<some free port>
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.authenticate=false
After the tomcat is restarted you can simply start jconsole (part of jdk) or visualvm and create a new jmx connection to the port you have chosen above.
In both tools you also have an option to take a dump ;)
!!!But do that only in closed/secured environment - since there is no authentication set.!!!
add java melody to your server
https://code.google.com/p/javamelody/
it give you a lot of info including threads in runtime
The following steps should help you get the current Java threads running and analyze them:
Download IBM JCA which is a nice thread dump analyzer from IBM Thread & Dump Monitor Analyzer
Execute the following to get the Tomcat threads dump: root#localhost:~# sudo -u $TOMCAT_USER $JAVA_HOME/bin/jstack -J-d64 -l $(ps aux | grep '[c]atalina' | awk '{print $2}') > ~/threads.log
Open the threads dump with IBM Thread & Dump Monitor Analyzer
Note: Replace $JAVA_HOME with your path to your current JDK, $TOMCAT_USER with the user running Tomcat; if you pass the wrong user or even using root you will get an error like this:
3047: well-known file is not secure
Please try netbeans profiler to profile any web applications.
https://profiler.netbeans.org/
http://wiki.netbeans.org/FaqProfilerAttachRemoteServer
Related
I tried a couple of options
a. cf java thread-dump myapp -i0 (Only 1 instance is there so 0)
Response is nothing.
logs of myapp show
2019-12-13T14:52:41.15+0800 [SSH/0] OUT Successful remote access by 10.x.x.x:35764
2019-12-13T14:52:41.84+0800 [SSH/0] OUT Remote access ended for 10.x.x.x:35764
b. I did cf ssh myapp
/home/vcap/app/.java-buildpack/open_jdk_jre/bin/ has no jstack and jmap command doesn't work either
/home/vcap/app/.java-buildpack/open_jdk_jre/bin/ has the following components
java orbd servertool java-buildpack-memory-calculator-3.13.0_RELEASE pack200 tnameserv
jjs policytool unpack200
jvmkill-1.16.0_RELEASE rmid
keytool rmiregistry
Question is-> How to get the java threaddump?
I believe the easiest option is to run cf logs to watch your app logs. Then in a second terminal, cf ssh to the app and run ps aux and look for the process id of the Java process. Then run kill -3 <pid>. Your Java process will catch this signal and issue a thread dump. It will go to STDOUT, which conveniently goes to your app's log stream so it should show up in the first terminal.
The crummy part about this is that cf logs will inject some additional text at the beginning of every line, which makes it hard to load the thread dump into tools. You can usually strip that off with cut or awk, or you can redirect cf logs to a file, open with a text editor and find/replace the leading text.
Besides that you have a couple other options:
If you're using Spring, enable Spring Boot Actuators. You can then use the /actuator/threaddump endpoint to generate and download a thread dump (note the format for this is JSON, not the standard format)
Use an APM tool or profiler like NewRelic, AppDynamics, Dynatrace or YourKit. These are well supported by the Java buildpack and most will just work.
Use JMX. It's easy enough to enable with the Java buildpack, just set the env variable JBP_CONFIG_JMX to '{enabled: true}' and restage your app. Once enabled, you can open a tunnel with cf ssh -N -T -L 5000:localhost:5000 <APP_NAME>. Then open jvisualvm, make a new "local" JMX connection to "localhost:5000" and connect. Click the "Threads" tab and click the "Thread Dump" button. It might be a little slow as it's going across the tunnel, but give it a few seconds to finish and you should have a thread dump.
What won't work on Cloud Foundry are jstack and jcmd. The Java buildpack, at the time of writing, installs a JRE and these tools are no longer shipped with the OpenJDK JRE and for legal reasons can't be bundled with it. If you were inclined to do so, you could scp the tools and required shared libraries from a JDK up to your app container and run them, but it's a lot of work and not fun. I'm not super familiar with the cf java plugin, but I suspect it tries to use these tools, which used to be available, and no longer are there.
You should be able to get ThreadDumps with kill -3 <PID> and open that in heap analyzer such as eclipse memory analyzer (MAT) and select Thread Stacks
I stop seeing the local JVM processes in jvisualvm. I definitely have JVM processes running which I can verify with ps command.
$ ps aux | grep java -c
10
Here's empty jvisualvm window,
I tried adding JMX agent localhost:3333 as mentioned in this oracle article - Java VisualVM - Connecting to JMX Agents Explicitly. But I get can not connect to localhost:3333 using service:jmx
I see the processes in jconsole however.
Open VisualVm -> Window -> Application
Local JVM processes panel should appear on the left, with the same list of processes that JConsole shows
I have an Azure App Service running Tomcat 8.5 and can't seem to figure out how to do a thread dump. jstack is not recognized in the Console nor the DebugConsole.
On Azure App Service, all popular versions of Java had been installed at the path D:\Program Files (x86)\Java. Take version 1.8.0u73 as example, please see the figure below.
You can command set PATH=D:\Program Files (x86)\Java\jdk1.8.0_73\bin;%PATH% to add Java tools to the environment temporarily via the Kudu console tool. Then, the jstack tool is available in the current Kudu session.
Inspired by the previous answer, I created the following bat script (could be powershell, I suppose) that does the job:
powershell -Command "get-process java |select -expand id" > pid.txt
set /p id= < pid.txt
"%JAVA_HOME%\bin\jstack" -F %id% > out.txt
It uses the java version that you're using in your app (JAVA_HOME) and doesn't require any input from you. It's simple and does the trick. Just create a bat file in your wwwroot, for example, and run it whenever you want.
I know this is an old question but for Windows Apps on Azure App Service, this can be easily done by going to Azure Portal -> Diagnose and Solve problems blade -> Diagnostic Tools and then choosing Collect Java Thread dump from the left menu or the middle pane.
Get the PID of java process from Process Explorer of Kudu (Advanced Tools)
Use this command to collect thread dump:
jcmd Thread.print > D:\home\threaddump.txt
All,
I have a remote server that I recently enabled VNC for using vnc4server and Chicken for mac as the client.
The purpose for doing so was to enable running Java's Jconsole to monitor an executable jar file that is running my server logic.
However, after logging into my server using VNC, I keep getting an error when I try to use Jconsole on vnc.
It states connection failed do you want to try again. Now I am logged in as the same user that started the process.
Is there something I am missing when using jconsole in VNC? Also can I monitor my executable jar file remotely using Jconsole on my local machine?
These are the options I am including to run the jar file: java -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=9005 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.remote.ssl=false -Djava.rmi.server.hostname=ipaddress -jar path
Thanks
These JVM options fixed things. Fix found here: You need to pass to the VM: -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.local.only=false
https://forums.oracle.com/thread/1177644
This does not seem like an VNC issue- either the ports are not open, they are being blocked b a firewall, or there is some kind of permission/authentication issue with the app itself related to monitoring it.
In order to eliminate VNC as the cause (and use localhost in a local connection on jconsole), do "ssh -X REMOTHOST -n jconsole" and see. This will also eliminate the overhead of running the full X server and VNC.
Also on linux you can find out what process holds a port open by doing:
netstat -ap | grep PORT_NUMBER on the remote host you want to run on.
Colin
I am running JBOSS on Solaris10 and trying to shutdown and restart the JBOSS. When I restart the JBOSS I am getting the following error.
LifecycleException: Protocol handler initialization failed: java.net.BindException: Address already in use:33409
I got this problem before and used to kill the process id related to the port 33409 using the lsof command. Unfortunately the lsof command is not working in my solaris box. Is there any other command I can use to identify the process id related to the port number 33409 and kill that process id, so that I can restart the JBOSS without any port conflicts.
Thanks in Advance
Use <JAVA_HOME>/bin/jps -lvm to see all java processes with their main class and all its arguments and JVM arguments.
jps -lvm | grep 'org.jboss.Main' -- this is how I usually find PIDs of any running jboss processes.
You can identify the correct process with something like this:
$ ps -feA | grep "jboss"
It takes a bit of guesswork, but you´ll get the hang of it. Make sure you identify the correct process before killing it, though.