Experimental Physics and
Industrial Control System

[email protected] (Jeff Hill) · Fri, 18 Jun 1999 17:51:02 -0600

Steve,

The CA server uses a "free list" to allocate dynamic memory for clients.
The net result is that the CA server is less likely to fragment pool.
Another side effect is that larger blocks are allocated out of pool, and
blocks are not returned to pool when clients release them. Instead,
unused blocks of memory are returned to the "free list" where they are
reused when another client needs them.

When running "memShow()" you should see that memory consumption remains
constant at the "high water mark" set by the maximum client load on your
IOC. If you see a sustained memory consumption increase that tracks with
the number of client connect/disconnect cycles, and does not track with
the client load "high water mark" then you are experiencing a bug that
will need to be more closely investigated, but is not expected based on
our experience.

There was a bug in one of the R3.13 beta releases of EPICS where the client
library would _not_ disconnect from an IOC if the channel count dropped to
zero. In this situation all channel related resources were properly
released.
However TCP connection related resources were not immediately released when
the last channel on a particular IOC was deleted. Instead, TCP connection
resource
release was postponed until the client program finished executing or the
resources
were reclaimed when the client created a new channel on the IOC.

Jeff

> 	We are using:
>
> * mv167 VME Crate Controller with 4 MB of RAM
> * EPICS Version R3.13.0.beta11
> * MEDM Version 2.3.4a
>
> and we have the problem that when each MEDM window is launched, a little
> bit of IOC memory is allocated by the CA routines to deal with that
> particular window.  But, for some reason, even when that window is closed,
> that memory is not freed.  Eventually, because we are allowing various
> users to have their own MEDM windows, all of which can be running at any
> given time, the IOC memory all but disappears.  When MEDM itself is
> exited, a small portion of that memory is returned, but it is not nearly
> that same amount that was used.
>

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System