Experimental Physics and
Industrial Control System

Till Straumann <[email protected]> · Thu, 18 Mar 1999 17:03:47 +0100

Marty Kraimer wrote:

> Till Straumann wrote:
> >
> > One of our programmers consulted me because his device support module
> > deadlocked the database (i.e. one or two of the scanning tasks). This happened
> >
> > when his module read a field using dbGetField().
>
> Record/Device support is not allowed to call dbGetField or dbPutField.
> record/device support uses dbGetLink, dbPutLink instead.

I know. The deadlock I mentioned was not the problem, the problem is that
using dbGetLink() it seems to be possible to provoke a race condition.

>
> Reading Chapter 2 of the Application Developers guide should explain what
> happened.

Ok, AFAIK the only way to prevent the described race condition would be
making the input link e.g. MS hence making both records members of the
same lock set. What, if I want to do dbGetLink from a NPP NMS link?

Till Straumann

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System