EPICS Controls Argonne National Laboratory

Experimental Physics and
Industrial Control System

1994  1995  1996  1997  1998  <19992000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024  Index 1994  1995  1996  1997  1998  <19992000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
<== Date ==> <== Thread ==>

Subject: Re: database race condition?
From: Till Straumann <[email protected]>
To: Marty Kraimer <[email protected]>
Cc: "[email protected]" <[email protected]>
Date: Tue, 23 Mar 1999 10:33:08 +0100
Marty Kraimer wrote:

> The Application Developer's Guide states:
>
> "Lock sets prevent two different tasks from simultaneously modifying records in
> the same lock set."
>
> This allows algorithms to be developed via linked records with the guarantee
> that outside tasks, e.g. a CA server, will not modify something in the lock set
> while the algorithm is being executed. Fine grained locks do not provide this
> guarantee.
>

Well, this guarantee is not needed if we just want to atomically read a
(possibly old) value (read a NPP NMS link) and therefore we could get
away without locking a whole set (and possibly blocking the task that
just wants to read the link in question for a much longer time than needed).
But what we need is the guarantee that the value is not modified while
it is read by another task. I was just brainstorming how this could be done
with minimal changes.

Till.


Replies:
Re: database race condition? Marty Kraimer
References:
database race condition? Till Straumann
Re: database race condition? Marty Kraimer
Re: database race condition? Till Straumann
Re: database race condition? Marty Kraimer

Navigate by Date:
Prev: Re: Scan Record Tim Mooney
Next: Re: database race condition? Marty Kraimer
Index: 1994  1995  1996  1997  1998  <19992000  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: database race condition? Marty Kraimer
Next: Re: database race condition? Marty Kraimer
Index: 1994  1995  1996  1997  1998  <19992000  2001  2002  2003  2004  2005  2006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
ANJ, 10 Aug 2010 Valid HTML 4.01! · Home · News · About · Base · Modules · Extensions · Distributions · Download ·
· Search · EPICS V4 · IRMIS · Talk · Bugs · Documents · Links · Licensing ·