Fix excessive cpu usage in daq logging. - #69
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jclewett-warwick wants to merge 1 commit into
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In this case, the zmq::poll is testing the readiness of two channels, an input channel and an output channel.
The output channel is (almost) always ready, so the poll falls straight through, without the intended 1ms pause for thought.
In the case that the output channel is not ready (essentially if it's buffer is full), then the send code below fails silently anyway, negating the value of the poll completely.
By only polling the output channel, the CPU usage in the thread is reduced from 100% to 3%, which is kinder to users working on containers on laptops (my laptop is melting trying to run this code).