Client reconnection is not possible when after server goes offline
camilomarino opened this issue · 2 comments
Hello, when the server is turned off, the client cannot reconnect. I wanted to know if there is any way to tell the client that in case of not receiving the reply message (for example in 5 seconds) and try to reconnect.
Thanks for raising this issue. This is a known "feature" of ZMQ, @camilomarino. It was actually imageZMQ issue: #1! "Hangs at...". The most elegant fix is a great one from Pat Ryan @youngsoul #1 (comment). Take a look at that that. It may work well for you.
In my own projects, I use a "with Patience()" try / except block like this one in my imagenode main loop: see imagenode.py (see lines 33-46).
The "hanging" of the REQ client when the REP server restarts is a known ZMQ "feature" and is there by design (so that a dropped REQ won't go unnoticed by the sender). I use this ZMQ feature as a part of my own yin-yang-ranch project design -- I want the RPi's to know if they need to deal with a non-responsive imagehub.
Please the FAQ page in the documentation. It has a more complete discussion of this. See FAQ Question "Why does image sender need to restart when the image hub program restarts?"