[zeromq-dev] Inter thread communication for scalability

[Kenneth Adam Miller]

@AJ No, but I understand exactly why you suggested that. It's because I
haven't explained that thread 1 is doing critical work and it needs to
offload tasks to other threads as quickly as possible.

@Lindley, Thanks so much for helping me see the truth! I was getting awful
confused considering all the different bolony that could go on if I was
stuck with semaphores, and I couldn't really re-envision it. Is there any
kind of convenience function or core utility for de-serializing the data
you receive over inproc messages?


On Tue, Jan 14, 2014 at 12:49 PM, AJ Lewis <aj.lewis at quantum.com> wrote:

> In the zeromq example, couldn't you just skip thread 1 entirely?  Then the
> PULL socket from thread 2 takes uncompressed input from the source,
> compresses it, and shoves it out the PUSH socket to thread 3 for output.
>
> In this case, the PULL socket is the uncompressed pool and the PUSH socket
> is the compressed pool.  Just make sure your uncompressed pool doesn't fill
> up faster than thread 2 can compress it, or you'll need to implement some
> logic to prevent it from using up all the memory.
>
> AJ
>
> On Tue, Jan 14, 2014 at 01:16:32PM -0500, Lindley French wrote:
> > In this case your "buffers" are really just messages, aren't they? A
> thread
> > grabs one (receives a message), processes it, and writes the result into
> > another buffer (sends a message).
> >
> > The hard part is that ZeroMQ sockets don't like to be touched by multiple
> > threads, which complicates the many-to-many pattern you have going here.
> > I'm no expert, but I would suggest....
> >
> > Each "pool", A and B, becomes a single thread with two ZMQ inproc
> sockets,
> > one push and one pull. These are both bound to well-known endpoints. All
> > the thread does is continually shove messages from the pull socket to the
> > push socket.
> >
> > Each thread in "Thread set 1" has a push inproc socket connected to pool
> > A's pull socket.
> >
> > Each thread in "Thread set 2" has a pull inproc socket connected to pool
> > A's push socket and a push inproc socket connected to pool B's pull
> socket.
> > For each message it receives, it just processes it and spits it out the
> > other socket.
> >
> > The thread in "Thread set 3" has a pull inproc socket connected to pool
> B's
> > push socket. It just continually receives messages and outputs them.
> >
> > This may seem complicated because concepts that were distinct before
> > (buffer pools and worker threads) are now the same thing: they're both
> just
> > threads with sockets. The critical difference is that the "buffer pools"
> > bind to well-known endpoints, so you can only have a few of them, while
> the
> > worker threads connect to those well-known endpoints, so you can have as
> > many as you like.
> >
> > Will this perform as well as your current code? I don't know. Profile it
> > and find out.
> >
> >
> > On Tue, Jan 14, 2014 at 12:23 PM, Kenneth Adam Miller <
> > kennethadammiller at gmail.com> wrote:
> >
> > > So, I have two pools of shared buffers; pool A, which is a set of
> buffers
> > > of uncompressed data, and pool B, for compressed data. I three sets of
> > > threads.
> > >
> > > Thread set 1 pulls from pool A, and fills buffers it receives from
> pool A
> > > up with uncompressed data.
> > >
> > > Thread set 2 is given a pool from A that has recently been filled. It
> > > pulls a buffer from pool B, compresses from A into B, and then returns
> the
> > > buffer it was given, cleared, back to pool A.
> > >
> > > Thread set 3 is a single thread, that is continually handed compressed
> > > data from thread set 2, which it outputs. When data is finished
> output, it
> > > returns the buffer to pool B, cleared.
> > >
> > > Can anybody describe a scheme to me that will allow thread sets 1 & 2
> to
> > > scale?
> > >
> > > Also, suppose for pools A and B, I'm using shared queues that are just
> C++
> > > stl lists. When I pop from the front, I use a lock for removal to make
> sure
> > > that removal is deterministic. When I enqueue, I use a separate lock to
> > > ensure that the internals of the STL list is respected (don't want two
> > > threads receiving iterators to the same beginning node, that would
> probably
> > > corrupt the container or cause data loss, or both). Is this the
> appropriate
> > > way to go about it? Thread sets 1 & 2 will likely have more than one
> > > thread, but there's no guarantee that thread sets 1 & 2 will have equal
> > > threads.
> > >
> > > I was reading the ZeroMQ manual, and I read the part about
> multi-threading
> > > and message passing, and I was wondering what approaches should be
> taken
> > > with message passing when data is inherently shared between threads.
> > >
> > > _______________________________________________
> > > zeromq-dev mailing list
> > > zeromq-dev at lists.zeromq.org
> > > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
> > >
> > >
>
> > _______________________________________________
> > zeromq-dev mailing list
> > zeromq-dev at lists.zeromq.org
> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>
>
> --
> AJ Lewis
> Software Engineer
> Quantum Corporation
>
> Work:    651 688-4346
> email:   aj.lewis at quantum.com
>
> ----------------------------------------------------------------------
> The information contained in this transmission may be confidential. Any
> disclosure, copying, or further distribution of confidential information is
> not permitted unless such privilege is explicitly granted in writing by
> Quantum. Quantum reserves the right to have electronic communications,
> including email and attachments, sent across its networks filtered through
> anti virus and spam software programs and retain such messages in order to
> comply with applicable data security and retention requirements. Quantum is
> not responsible for the proper and complete transmission of the substance
> of this communication or for any delay in its receipt.
> _______________________________________________
> zeromq-dev mailing list
> zeromq-dev at lists.zeromq.org
> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.zeromq.org/pipermail/zeromq-dev/attachments/20140114/4a88218b/attachment.htm>