STOP and START a running process.

Send signals to the running process.

# sending STOP signal to the process will halt the process in it's current state.
sudo kill -STOP $pid.

# To confirm the process is stopped for a moment
sudo strace -p $pid. #this will leave traces of "STOPPED".

# send CONT signal to resume the process to start it's work
sudo kill -CONT $pid.


Inorder to make the process idle (to simulate deadlock situation) I've used the above technique to stop the process and test the status of the process.