Very Computer

by **chwan** » Sun, 24 Nov 1996 04:00:00

I am doing a project about a shared memory for multiple
producers and consumers. So far I have done a producer
and a consumer sharing a memory without any problem.

However, when I fork the second producer in producer(), and/or
the second consumer in consumer(), I can't get the correct
result. The 2nd producer overwrites what the 1st producer
had done, and when the 2nd consumer access the share memory, the
1st consumer automatically receives what the 2nd consumer had
taken.

Can someone kindly show me some suggestions?
Thank you very much in advance if there are some.

by » Sun, 24 Nov 1996 04:00:00

Quote:> However, when I fork the second producer in producer(), and/or
> the second consumer in consumer(), I can't get the correct
> result. The 2nd producer overwrites what the 1st producer
> had done, and when the 2nd consumer access the share memory, the
> 1st consumer automatically receives what the 2nd consumer had
> taken.

Are you serialising the processes? If more than one process can read
and/or write the same shared memory, you should use some technique that
guarentees exactly one process at time will execute the read or write
(which is called serialising). One way is to require each process down an
IPC style semaphore before access and then raise it after. Another is to
lock a well known file before and then unlock it after. There are probably
others.

You can also use IPC queues to communicate in a serialised fashion.

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Very Computer

Question ab/ multiple producers/consumers

Question ab/ multiple producers/consumers

Question ab/ multiple producers/consumers