How to identify tempdb space usage

Sometimes our tempdb gets full and fills the disk. Hence it cant expand and due to its a lots of our operation either stucks or starting failing.
At this time we immediately need to find which process is taking so much space in tempdb and which type of  operation by that process is taking space to troubleshoot the issue ASAP

Distribution Cleanup failed due to security reasons

Recently we got following error in Distribution Cleanup for Replication 


Replication-@rowcount_only parameter must be the value 0,1, or 2. 0=7.0 compatible checksum. 1=only check rowcou: agent distribution@rowcount_only parameter must be the value 0,1, or 2. 0=7.0 compatible checksum. 1=only scheduled for retry. Could not clean up the distribution transaction tables.