[zeromq-dev] duped sockets and fork

[Selim Ciraci]

Sorry forgot to mention, exec itself is not possible. Child-child executes
from a different piece of code from where child has left. And in parallel
child executes a different code.

Thanks,
Selim


On Thu, Sep 12, 2013 at 2:35 AM, Michi Henning <michi at triodia.com> wrote:

> How about having the client exec itself after a fork, with the
> close-on-exec flag set? That would give each forked client a clean slate to
> start with.
>
> Michi.
>
>
> On 12/09/2013, at 19:29 , Selim Ciraci <ciraci at gmail.com> wrote:
>
> > Hi,
> >
> > We have client/server program, the server is a process itself that is
> started separately from the client. The client on the other hand from time
> to time forks workers (we have to use fork because we are parallelizing a
> huge piece of code that is not thread safe at all). After forking the
> initial client also does some work and then checks its children.
> > The child processes, immediately after forking create a context and open
> connection to the server.
> > The childern themself can form new processes. These 'child-child'
> processes also create a context and open connections to the server.
> > Now the problem is that fork caries the parent sockets to the children.
> This means that a child-child-child-child... process can end up with too
> many open sockets such that opening more sockets are not possible In fact
> in this case, Zmq aborts with too many open sockets in signaler.cpp:230.
> The question is how can close parent sockets safely from child? (I cannot
> use zmq_ctx_destory with parent context)
> > I read about certain 'hacks' that read the fds from /proc and close them
> one by one. The problem with this solution is that I don't know which fds
> are sockets, I might end up closing an fd used for file operations.
> > Zmq sockets are void*. is there a way to get the low level descriptor
> from these void* sockets?
> > Any suggestions to fix this problem? I'm stuck with fork and I cannot
> change the architecture.
> >
> > Thanks!
> > Selim Ciraci
> >
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