[zeromq-dev] hwm puzzle

[Martin Sustrik]

Hi Andrew,

> surely i am doing something wrong. but i can't see it.
> what am i doing wrong?

Due to the fact that 0MQ is implemented in the user space, there are two 
buffers on each side of connection instead of one: user-space (0MQ) 
buffer and kernel-space (TCP) buffer. The limit for the former is set by 
ZMQ_HWM option while the limit for the latter is set by 
ZMQ_SNDBUF/ZMQ_RCVBUF (which translate directly to TCP SO_SNDBUF/SO_RCVBUF).

Martin