How to find which process is using a port in Windows

Often, we find a port is blocked by some application or process.

Use this command prompt command to find out which process is using the busy port:

netstat -ano|find "3306" 

Output of this command will be as follows, if the port is currently being used by some process:

  TCP    0.0.0.0:3306           0.0.0.0:0              LISTENING       4824
  TCP    [::]:3306              [::]:0                 LISTENING       4824

 
In this case process 4824 is utilising the port 3306.

Now, you can kill the process using command prompt or  use the pid(here 4824) number and find the process name in windows task manager and stop it.

Like, I got the blocked port error with XAMPP while I was trying to start MySQL which may occur due to blocked port.

My error log was as follows:

2015-11-10 15:26:56 10fc InnoDB: Warning: Using innodb_additional_mem_pool_size is DEPRECATED. This option may be removed in future releases, together with the option innodb_use_sys_malloc and with the InnoDB's internal memory allocator.
2015-11-10 15:26:56 4348 [Note] InnoDB: Using mutexes to ref count buffer pool pages
2015-11-10 15:26:56 4348 [Note] InnoDB: The InnoDB memory heap is disabled
2015-11-10 15:26:56 4348 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions
2015-11-10 15:26:56 4348 [Note] InnoDB: Memory barrier is not used
2015-11-10 15:26:56 4348 [Note] InnoDB: Compressed tables use zlib 1.2.3
2015-11-10 15:26:56 4348 [Note] InnoDB: Not using CPU crc32 instructions
2015-11-10 15:26:56 4348 [Note] InnoDB: Initializing buffer pool, size = 16.0M
2015-11-10 15:26:56 4348 [Note] InnoDB: Completed initialization of buffer pool
2015-11-10 15:26:56 4348 [Note] InnoDB: Highest supported file format is Barracuda.
2015-11-10 15:26:57 4348 [Note] InnoDB: 128 rollback segment(s) are active.
2015-11-10 15:26:57 4348 [Note] InnoDB: Waiting for purge to start
2015-11-10 15:26:57 4348 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.26-74.0 started; log sequence number 1835027
2015-11-10 15:26:57 6140 [Note] InnoDB: Dumping buffer pool(s) not yet started
2015-11-10 15:26:57 4348 [Note] Plugin 'FEEDBACK' is disabled.
2015-11-10 15:26:57 4348 [Note] Server socket created on IP: '::'.
2015-11-10 15:26:57 4348 [Note] Event Scheduler: Loaded 0 events
2015-11-10 15:26:57 4348 [Note] C:\xampp\mysql\bin\mysqld.exe: ready for connections.
Version: '10.1.8-MariaDB'  socket: ''  port: 3306  mariadb.org binary distribution
2015-11-10 15:27:11 5152 [Note] C:\xampp\mysql\bin\mysqld.exe: Normal shutdown

2015-11-10 15:27:11 5152 [Note] Event Scheduler: Purging the queue. 0 events
2015-11-10 15:27:11 5732 [Note] InnoDB: FTS optimize thread exiting.
2015-11-10 15:27:11 5152 [Note] InnoDB: Starting shutdown...
2015-11-10 15:27:13 5152 [Note] InnoDB: Shutdown completed; log sequence number 1835037
2015-11-10 15:27:13 5152 [Note] C:\xampp\mysql\bin\mysqld.exe: Shutdown complete

So, I checked for blocked port of MySQLin XAMPP which was used by MySQL57 (another instance of MySQL)

I clicked on 'Services' and stopped 'MySQL57'. After that, I started MySQL in XAMPP and it worked fine :)