Abstract: DLM uses 6 kinds of locks, which makes not only more concurrency in distributed systems, but also more difficult management of locks. Then Petri net works. The Petri net model of a distributed system is compounded from the simplified Petri net of its subsystems. With the reachable marking graph of the system's Petri net, deadlocks can be detected in real time, which processes in the deadlock chain will also be known.

Key words: Distributed system, Lock management, DLM, Petri net, Deadlock detection