I have a question that briefly browsing the zmq 3.2.3 code has not answered for 
me.

1.       Suppose I have a multithreaded process in which any number of pthreads 
may have zmq sockets/endpoints performing messaging.

2.       One of those threads - it could be the main thread, could be any of 
the child pthreads - performs a fork, but does not perform one of the execs.
(execl,execlp,execle,execv,execvp).

3.       My question: what is known to be true in the child process' zmq 
context after the fork?  Specifically, what is the invariant for the zmq 
context, if the method "child" is called that is registered via pthread_atfork( 
void (*prepare)(void), void (*parent)(void), void (*child)(void))?


The child process "inherits the entire process space" of the pthread in which 
fork is called.  That includes the zmq context.  But the parent's zmq context 
is capable of closing all sockets across all of its pthreads.  The child 
process inherits only its parent pthread's socket(s) and endpoints.

Which sockets and endpoints does the child process' zmq context "know about"?  
If zmq_ctx_term is called within the child process immediately after fork - or 
in the "child" method registered via pthread_atfork - which sockets will the 
zmq context attempt to close?  Only those sockets created within the pthread 
that executed fork()?

Is the better question to ask: In the child process after such a fork, which 
sockets that the parent process' zmq context had open for all of its threads, 
remain open within the child process' zmq context?




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