Sometimes it may happen that you SSH into your Linux box and see the following message (where N is an integer > 0):
=> There are N zombie processes.
There's nothing to worry about. Zombies won't eat your server. They're just confused. Use the following command to get the process IDs:
ps axo stat,ppid,pid,comm | grep -w defunct
Then, kill them one by one with sudo kill -9 PID where PID is the process ID.