Sometimes because of some issue or bug, our application may stop working, but the port will be locked. This kind of issue is very common with MySQL server, Elasticsearch, WebServices, Tomcat etc. In such scenarios, we have to find the zombie process and kill it to free up the locked port.
How to find the process that locks the port?
Use the following command
netstat -tulpn | grep <port>
This output of this command will contain the process id. Now we just need to kill the process.
Verify the process
Before killing the process, figure out what process it is and ensure we are not killing any required processes.
ps -aux | grep <process id>
The output of the above command will give the details of the process.
How to Kill a process ?
After confirming the details, you can kill the process
kill -9 <process id>
Now verify whether the port is still locked or not by executing the netstat command again