3.deadlock prevention

*negate one of the necessary conditionsNegating Mutual Exclusion :

example:shared use of a printer

»give exclusive use of the printer to each user in turn wanting to print?
»deadlock possibility if exclusive access to another resource also allowed
»better to have a spooler process to which print jobs are sent

-­complete output file must be generated first

example: file system actions

»give a process exclusive access rights to a file directory

example: moving a file from one directory to another

­-possible deadlock if allowed exclusive access to two directories simultaneously
­-should write code so as only to need to access one directory at a time