DHCP module and external DHCP relay

[Alan DeKok]

  Let me go further...

  My guess is that you're using MySQL to store IPs.  You're using a
"SELECT FOR UPDATE ... LIMIT 1" query to grab the IP.

  That's the problem.  MySQL will lock all of the rows SELECTed, even if
you say LIMIT 1.  The result is massive lock contention, and MySQL will
take many seconds to respond.

  Use a real database, like PostgreSQL. The problem will go away.

  Alan DeKok.