Experimental Physics and
Industrial Control System

Hi Matt,

Many thanks for the suggestions.

> What version of pyepics are you using?

I think I am using pyepics-3.2.1, but not 100% sure.  Is there a command that can tell which version I am using?

> Why do you want to do this?

Well, just wanted to make the program more ioc friendly.  Closing the unused connections releases the resources (file descriptors, memory) of the iocs.  My program is a daemon program.  If it does not close the connections it has opened and are no longer needed, those connections will remain open forever. 

Also how about the unresolved pv searches; will my program keeps searching those unresolved pvs forever if it does not close them explicitly?  So I think by closing the unused or unresolved pvs, these problems can be avoided.

>    import gc
>    gc.collect()

Calling gc.collect() after executing pv = None, the connection remained open.  So this does not work.

>    epics.ca.clear_channel(chid)
>    ctx =epics.ca.current_context()
>    epics.ca._cache[ctx].pop(pvname)

Yes, this works!  This clears the connection and also allows re-creation of a channel on the same pv.