[zeromq-dev] zpoller and lvcache backend socket misses new subscribers to duplicate topic

Luca Boccassi luca.boccassi at gmail.com
Thu Mar 8 23:39:38 CET 2018

On 8 Mar 2018 21:14, "Rich Schramm" <rich at mbari.org> wrote:

I am trying to implement lvcache from example with the czmq vsn 4.1.0. api
I want to send last value from cache to any new subscriber to a topic.  My
problem is that only the first subscriber to a topic is seems to trigger an
event for the backend XPUB socket in the poller_wait loop …  ie 1st client
subcriber to topic “FOO” and first client subscribing to topic  “BAR” both
are recognized.  A third client also starting a subscription to “FOO”
doesnt appear to be detected at the poller_wait.
Likewise, the poller also doesnt trigger again until all clients that have
subscribed to ‘FOO” are killed.
Is this expected behavior and/or how can I make sure that every client
subscribing is recognized and receives the topic’s initial cached value?

-Rich Schramm

To get duplicated subscriptions you need to set the xpub_verbose socket
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