[zeromq-dev] Logging HWM events?

Tom Wilberding tom at wilberding.com
Wed Sep 28 19:37:28 CEST 2011

Hi Martin,

I think we found the root cause. It appears that one of the clients was
consuming very slow.

We saw the transmit buffer on the TCP PUB grow and grow to over 1GB by
monitoring the mem usage of the repeater process.

When we killed the slow TCP SUB client, the memory on the repeater
plummeted instantly from 1GB to 30MB (we are not using durable sockets).

I was not explicitly setting a HWM. Is the default no limit?

We will fix the slow client (suicidal snail) and we will explicitly set
a HWM for our TCP PUB.

> What is the HWM for a TCP PUB/SUB? Can I increase this via socket
> options?
> I'm going to gather memory usage stats from the repeater every 30 sec
> and try to understand how much memory I need properly handle the input
> traffic and still have capacity for large spikes.

Without the slow client, the repeater memory has remained sub 100MB all
day, so we are encountering minimal buffering when all of the consumers
are healthy.


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