Timer based threads

[Mugdha]

I have created two threads ( thread1 and thread2 ). These two threads use a common buffer.
I want to implement the following logic:

After EVERY 100 sec thread1 starts , if available aquires lock for writing data into the buffer ,writes data into the buffer, release the lock.
After every 500 sec thread2 starts ,if available aquires lock , reads data from the buffer .

In short i want to make my threads execute periodically .
I m NOT USING RTLINUX .....
how do I create timer based threads......where can I set the time attribute for a thread.
Or is it essential to send signals to thread after the required time interval ?
How to set the run state for a thread?
Is it necessary to have RTLINUX as it provides system calls like pthread_make_periodic_np() etc...????

[wje_lf]

You're using POSIX threads, so you don't need RTLINUX. Any Linux will do.

But I would highly discourage you from using POSIX threads unless absolutely necessary. The reason is that all threads share the same heap address space, and if there is a bug in one thread that stomps on memory it shouldn't, the bug might show itself by making a different thread misbehave. Very difficult to debug. Use fork() to produce a child process. Either the parent can be the writer and the child can be the reader, or the other way around. Your choice.

Use mmap() and /dev/zero to create shared memory. Do this in the parent process before fork()ing.

Use file locking to synchronize between the threads. That will involve calling fcntl() with the commands F_RDLCK, F_WRLCK, and F_UNLCK.

For doing things periodically, use sleep().

Hope this helps.