[zeromq-dev] Reduce zeromq memory usage?

[David Wolfe]

> > Can anyone offer advice on how to reduce zeromq's memory usage for
> > an embedded app?  I think zmq_init() uses the default stack size
> > (8192 KB in Linux), which is a pretty big chunk...

[@Chuck Remes]
> ...  the "ulimit" command can be used to modify the default stack size
> from a shell prior to launching your application.

That worked really well, thanks. Writing a little wrapper that says:

#!/bin/sh
ulimit -s 32
./usr/bin/testServer &

decreased the %MEM reported by top from 19% to 5% (of 64MB total).
This is comparable to the app I'm replacing.


> > Also, for tcp, the buffers corresponding to SO_SNDBUF and SO_RCVBUF
> > are probably defaulting to their maximums (128K each, I think).

[@Chuck Remes]
> Take a look at the man page for setsockopt(). There are accessors for
> both send and receive buffers that you can use to tune the sizes.

I set the snd/rcv buf sizes to 32K and this shaved off another 384KB.
Not as dramatic a difference as changing the stack size, but it'll
definitely help---particularly in the 'real' server when I'm servicing 4
or 5 clients.


[@Martin Sustrik]
> Also, have a look at src/config.hpp. in_batch_size and out_batch_size
> define size of the internal 0MQ's buffers that it uses for batching
> inbound/outbound data.

Thanks for pointing this out. It's nice to know where the 'knobs' are if
I need to reduce memory usage further.  Things are looking pretty good
now...