Multithreaded fork

Question

Can fork() function be used to replicate a multithreaded process. And if so, will all threads be exactly the same and if not, why not. If replication can't be done through fork, is there any other function which can do it for me?

Have you seen this question? Or this one? Basically only the fork()ing thread survives in the child process. What are you trying to achieve? — Zecc
– Zecc, Commented May 19, 2011 at 10:17
Actually I was trying to create a replicated process for reliable execution, where the replicated process would verify the outputs from primary process by executing the same code. — MetallicPriest
– MetallicPriest, Commented May 23, 2011 at 13:20

Community · Accepted Answer · 2017-05-23 11:45:46Z

27

After a fork, only one thread is running in the child. This is a POSIX standard requirement. See the top answer to the question fork and existing threads ?.

edited May 23, 2017 at 11:45

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answered May 19, 2011 at 10:06

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Comments

Mayank Jain · Accepted Answer · 2024-11-15 16:30:38Z

No, the child will only have one thread. Forking a threaded process is not trivial. (See this article Threads and fork(): think twice before mixing them for a good rundown).

I don't know of any way of cloning a process and all its threads, I don't think that's possible on Linux.

Intrepidd · Accepted Answer · 2011-05-19 10:06:11Z

No.

A fork creates a new process with his own thread(s), copies the file descriptor and the virtual memory.

A child process does NOT share the same memory with his father. So this is absolutely not the same.

Nizam Mohamed · Accepted Answer · 2022-06-29 21:33:24Z

Suppose that one of the other threads (any thread other than the one doing the fork( )) has the job of deducting money from your checking account.

POSIX defined the behavior of fork( ) in the presence of threads to propagate only the forking thread.

If the other thread has a mutex locked, the mutex will be locked in the child process, but the lock owner will not exist to unlock it. Therefore, the resource protected by the lock will be permanently unavailable.

http://www.doublersolutions.com/docs/dce/osfdocs/htmls/develop/appdev/Appde193.htm

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