Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Wed, 27 Apr 2011 10:18:59 -0600

Hi Carston,

> Create any PVs at softIoc, request it via caget and you see the handle
> count at softIoc will be increased by two 

Are you using the native win32-x86 EPICS base port to windows, or the
cygwin-x86 (utilizing the cygwin Posix emulating layer) EPICS base port to
windows?

Does your caget run at a high repetition rate? If so, what might be
happening is that, despite being properly cleaned up by the ca library, the
tcp circuits are lingering, and continuing to consume resources for a finite
time period, in the TIME_WAIT state. The netstat program, invoked from the
DOS command line, on windows shows how many tcp circuits are active, and in
what state they are in.

What diagnostic are you using at your site to reveal the incrementing handle
count?

By the way, there are typically one tcp socket and one UDP socket created by
each invocation of caget. If the client side application program calls
ca_context_destroy then these sockets are explicitly closed by the ca client
library, but if the process exits before the application explicitly calls
ca_context_destroy then the OS typically will implicitly close the sockets
during orderly process rundown procedures. A quick search in the source
reveals that caget, at least in some scenarios, explicitly calls
ca_context_destroy.

> If you frequently repeat this procedure you will end up to in a "WINSOCK
> Error 10055".

On Winsock error code 10055 is WSAENOBUFS which is the Winsock rough
equivalent of ENOBUFS on UNIX. I don't recall encountering WSAENOBUFS with
Winsock. Perhaps it results from network kernel buffer starvation as is the
case with BSD network kernels, from which the Microsoft network kernel is
rumored to be derived. However, after reading the description below it
appears that the WINSOCK interface is quite vague about what resource might
be in short supply.

http://support.ipswitch.com/kb/WSK-19980714-EM18.htm

Jeff
______________________________________________________
Jeffrey O. Hill           Email        [email protected]
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> -----Original Message-----
> From: [email protected] [mailto:[email protected]]
> On Behalf Of Carsten Winkler
> Sent: Wednesday, April 27, 2011 5:29 AM
> To: [email protected]
> Subject: Handle leak in Channel Access Server V4.13 (current EPICS base) -
> WinXP
> 
> It seems to be a handle leak in Channel Access Server V4.13 (current EPICS
> base)
> 
> Create any PVs at softIoc, request it via caget and you see the handle
> count at softIoc will be
> increased by two and won't be freed anymore (without using any EPICS
> gateway).
> If you frequently repeat this procedure you will end up to in a "WINSOCK
> Error 10055".
> 
> This problem occurs at Windows XP with patched EPICS bas 3.14.12.
> 
> How can I fix this bug without using EPICS gateways?
> 
> Best Regards,
> Carsten Winkler
> 
> ________________________________
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System