Experimental Physics and
Industrial Control System

Matt Newville <[email protected]> · Thu, 21 Apr 2011 13:22:13 -0500

Hi Mark,

On Thu, Apr 21, 2011 at 9:12 AM, Vigder, Mark
<[email protected]> wrote:
> I did exactly as you suggested below. I assumed that the exception
> being returned was a mistake. I'll pull the latest version with
> the fix.

Thanks.

> Another option for making the code more "plain looking" is to
> use a single CA context and subclass Python's threading.Thread.
> This subclass can be used for creating threads in PyEpics and
> the subclass could switch to the single context in use. This
> of course only works if there is a single context for the
> application.

Subclassing threads seems like more work to me too.  The change to PV
to save its context and then make sure that is used for put() and
get() is just a couple lines of code -- I can check that the context
is correct in the same routine used to make sure the channel is
connected.  And that does allow PVs created in the main thread to be
used in child thread.  Creating PVs in a non-main thread still
requires creating a new context.

I pushed a branch (pv_savecontext) with this change to github.  It
seems to work, but I have not fully documented this or tested it on
all systems.   The simple tests work for me on linux and windows.

Cheers,

--Matt

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System