Experimental Physics and Industrial Control System
Hi Matt,
I won't have time for a considered reply for a bit; in particular, I think I'll have to actually write an proper implementation of catools using callbacks for a really considered reply (as I said before, the error handling is particularly troublesome as the flow of control gets scattered), and that's got to wait its turn, maybe a suitable soggy day.
However I think I can sensibly respond to your conclusion straight away.
From: [email protected] [mailto:[email protected]]
> So, if I understand correctly, a principle motivation is that you
> prefer many threads over relying on pre-emptive callbacks. With that
> preference, thread "weight" becomes a serious issue, so much so that
> you cannot rely on standard python threads. Is that a fair
> assessment?
Not unfair, though historically slightly backwards: an equally strong motivation is avoiding event callbacks at an inconvenient time. Or, to reiterate an earlier point, cothread allows the naive, lazy or busy programmer to avoid having to worry about thread synchronisation and locking issues, because diversion of flow of control can only happen at well defined and easy to understand places. I suspect this is a bigger win than most people realise.
I've just checked with James who did the original work that led up to cothread and cothread.catools and the history is rather interesting: it turns out that the original motivation for using coroutines (or "greenlets" as the library we used called them) was to avoid problems with Qt3 caused by triggering Qt operations from the wrong thread, and this problem was encountered before working on channel access bindings. In other words, coroutines were introduced precisely to avoid a thread synchronisation problem with Qt.
As for callback driven versus thread driven code, yes, I am arguing that threaded code is clearer, but it does seem that more examples are needed.
--
This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail.
Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd.
Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message.
Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom
- Replies:
- Re: Invitation to test cothread.catools release candidate Matt Newville
- References:
- Invitation to test cothread.catools release candidate michael.abbott
- Re: Invitation to test cothread.catools release candidate Matt Newville
- RE: Invitation to test cothread.catools release candidate michael.abbott
- Re: Invitation to test cothread.catools release candidate Matt Newville
- RE: Invitation to test cothread.catools release candidate michael.abbott
- Re: Invitation to test cothread.catools release candidate Matt Newville
- Navigate by Date:
- Prev:
Re: Invitation to test cothread.catools release candidate Matt Newville
- Next:
EPICS performance evaluation ssahoo
- Index:
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
<2012>
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
- Navigate by Thread:
- Prev:
Re: Invitation to test cothread.catools release candidate Matt Newville
- Next:
Re: Invitation to test cothread.catools release candidate Matt Newville
- Index:
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
<2012>
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024