Also known an Ricart and Agrawala’s algorithm.

• Nodes use logical clocks: all events are in total order.

• When a node wants to enter a CS (Critical Section) it sends a message.

• The message contains following information

1. Process id of the process

2. The name of CS that the process wants to enter

3. A unique timestamp generated by the process for request msg

• When a node receives such a request

1. If it is not interested in this CS, it replies OK immediately.

2. If it is interested in this CS:

If its message’s timestamp was older, then replies OK,

Else, it puts the sender in a queue and doesn’t reply anything (yet)

3. If it is already in the CS, it puts the sender in a queue and doesn’t

reply anything (yet).

• A node enters the CS when it received OK from all other nodes.

• A node that exits the CS, sends immediately OK to all nodes that it may have

placed in the queue.-Also known an Ricart and Agrawala’s algorithm.

•　Nodes use logical clocks: all events are in total order.

•　When a node wants to enter a CS (Critical Section) it sends a message.

•　The message contains following information

1. Process id of the process

2. The name of CS that the process wants to enter

3. A unique timestamp generated by the process for request msg

•　When a node receives such a request

1. If it is not interested in this CS, it replies OK immediately.

2. If it is interested in this CS:

If its message’s timestamp was older, then replies OK,

Else, it puts the sender in a queue and doesn’t reply anything (yet)

3. If it is already in the CS, it puts the sender in a queue and doesn’t

reply anything (yet).

•　A node enters the CS when it received OK from all other nodes.

•　A node that exits the CS, sends immediately OK to all nodes that it may have

placed in the queue.