doubt regarding os threads

[navenmou]

Does fork()duplicate only the calling thread or all threads?

 

[trav1s]

Only the calling thread.

 

[horace1]

Does fork()duplicate only the calling thread or all threads?

under Unix fork() creates a clone (copy) of the process and executes it concurrently with the parent. The only difference between the two processes is that fork returns the child process ID to the parent and zero to the child

 

[amraldo]

fork is for processes not threads.
--
Amr

 

[navenmou]

fork is for processes not threads.
--
Amr

but the process has contain multiple threads so while we are using fork() system call for creating the process indirectly it also creat threads..

 

[horace1]

processes and threads are different things.
A process is program in execution made up of heap, stack, fixed data, code, registers, etc.
fork() creates a clone (a copy) of a process and runs the parent and child concurrently, i.e. you have two copies of the same program executing at the same time (on a single CPU machine they will time share).

When new thread is created it uses the same address space as the parent process, i.e. they share code and global variables – but have own local variables.
It is still one process but with two internal threads of control, i.e. the threads can read/write data from/to the same variable in the memory of the process.
Of course you can then fork() it and have two processes each with two threads of control.