How to Take a Heap Dump from Tomcat : Windows

 Hi All, 

This post is to quickly check how to take a heap dump from Tomcat running on Windows machine. 

1. First open a command prompt running as Administrator
2. First we have to find the process ID of running Tomcat. For that it would be easy to know the Tomcat running port. In my case it's 8081. Therefore I'll execute the following command. 
   
   
   > netstat -ano | findstr 8081
   
   
   
   
   
3. Create a folder to store the dump file
4. Execute the following command.
   
   
    jmap -dump:file=E:\dump\myheapfump.hprof -F <process_id>
   
   
   
   
   
   
5. Now you can analyze the heapdump using a tool like eclipse memory analyzer 

Hope that helps, 
Thanks. 

Useful Docker Commands for Beginners

Hi Everyone, 

Being a newbie to docker, I thought of sharing some useful commands running docker. 

1. List the images
   

   sudo docker image ls

   
   
2. List the running containers
   

   sudo docker container ls

   
   
3. Build and tag a docker image
   

   sudo docker build -t <name_of_the_image> . 

   
   
4. Run a docker image
   

   sudo docker run -p 8888:8080 <name_of_the_image>

   
   
5. Check the java version running on a container
   
   First list the containers using

   sudo docker container ls

   Then execute the following command to check the running java version of the container. You have to use the container id obtained from the previous output.
   

   sudo docker exec <container_id> java -version

   
   
6. Delete Container
   

   sudo docker container rm <container_id>

   
   
7. Delete Image
   

   sudo docker image rm <image_id>

Hope it helps.

Thanks.

How to Share a Folder Between VirtualBox and Windows

Hi Everyone,

In order to share a folder between VirtualBox and Windows, we have to follow the following steps.

1. Install Guest Additions. You can do this by clicking on the following menu item, once the virtual machine is started up.



2. Create a folder in your Windows machine and then share it with your virtual machine. Go to machine settings -> Shared Folders -> Add new Shared Folder.



Make sure to click on Auto-mount and Make Permanent check boxes.

3. Restart the Virtual Machine. Now you can see the shared folder added. However still you can't access the shared folder.



4. Shared folder is owned by the vboxsf user group. You can check this by checking the properties of the folder.



5. Add the current user to vboxsf group using the following command.

• sudo adduser vboxsf

6. Now restart the VM and you'll be able to share files between the VM and the Host through this folder.

Hope it helps.

Thanks.