94.401 Operating Systems

154

Enforcing mutual exclusion with message passing

ncreate a mailbox mutex shared by n processes

nsend() is non blocking

nreceive() blocks when mutex is empty nInitialization: send(mutex, “go”); nThe first Pi who executes receive() will enter CS. Others will be blocked until Pi resends msg.

Process Pi:

var msg: message;

repeat

receive(mutex,msg);

send(mutex,msg);

forever