Sychronize process using pipe?

can pipe sychronize thread or process? because I'm trying to create 5 thread or process that can take an integer value and display it. each time a thread display the value, it has to be decrement it by 1 until the value has reach 0. The problem that I'm having is how can that integer value be transfer to those 5 process or thread for those 5 thread needs to be running concurrently. Do I just fork() 5 thread first??..I'm really confuse on this...

sorry for my bad grammer

First, fork() doesn't create threads, it creates a copy of your current process. With that said, you can use pipe() (or popen()) to do process synchronization. The basic idea is that a process is blocked if it attempts to read() from the pipe handle and there is no input available to read. You can use this to synchronize between processes. Google for "IPC pipe" or "process synchronization popen" for examples.

Hi there,

I think you should read this tutorial on threads first.

Basically, if you use a fork, you spawn processes.
However, 1 process can spawn many threads. You would basically want to avoid using processes and use threads instead since they are move efficient.

Things you should know about threads.
In a multithreaded prgm:
all globals among all the threads. If you want private global variables, look at Private Thread data (also covered in the link I provided)
All local variables are local to the thread within they are spawned.
If multiple threads need to access a single resource, you need to use some sort of locking mechanism, like mutex locking.
If you have multiple threads working on a single problem, you will need to use synchronization.

hopefully that helps.