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Subject: Runaway connection count on IOC
From: <michael.abbott@diamond.ac.uk>
To: <tech-talk@aps.anl.gov>
Date: Mon, 11 Jun 2012 07:17:24 +0000
I have a very odd problem with one particular vxWorks (EPICS 3.14.11) IOC, where the connection count as reported by casr climbs into the many thousands, all to one client (the gateway server).  Simply running `casr 2` is enough to clear this condition!

Let me try and be precise.

1. The server is vxWorks 5.5.1 and EPICS 3.14.11

2. The server is running an asyn driver interfacing to a firewire camera and providing images over EPICS

3. The ethernet connection is horribly horribly overloaded (100MBit link), EPICS would like to deliver far more image frames than the network will permit

4. The EPICS gateway clearly struggles to connect to the IOC, typically most of the PVs provided by the IOC are inaccessible through the gateway.

5. At some random point during operation the number of IOC connections ($(IOC):CA:CNX as reported by vxStats) starts climbing steadily.

6. Running casr reports that practically all of these connections are to the gateway, for example:

SR01C-DI-IOC-02 -> casr
Channel Access Server V4.11
Connected circuits:
TCP 172.23.194.201:38552(cs03r-cs-gate-01.cs.diamond.ac.uk): User="gate", V4.11, 8697 Channels, Priority=0
TCP 172.23.194.38:59307(cs03r-cs-serv-38.pri.diamond.ac.uk): User="epics_user", V4.11, 12 Channels, Priority=0
TCP 172.23.194.201:38553(cs03r-cs-gate-01.cs.diamond.ac.uk): User="gate", V4.11, 18 Channels, Priority=0
TCP 172.23.194.27:50143(cs03r-cs-serv-27.pri.diamond.ac.uk): User="archiver", V4.11, 1 Channels, Priority=20
TCP 172.23.194.28:52559(cs03r-cs-serv-28.pri.diamond.ac.uk): User="archiver", V4.11, 1 Channels, Priority=20

7. Running `casr 2` takes forever (well, several minutes), the connection is over a 9600 baud serial line.  Of the 8697 channels, the same PV is reported over and over and over and over again (it's a simple camera STATUS provided by the asyn driver).

8. After `casr 2` has completed, the bogus channels have gone away:

SR01C-DI-IOC-02 -> casr
Channel Access Server V4.11
Connected circuits:
TCP 172.23.194.201:38552(cs03r-cs-gate-01.cs.diamond.ac.uk): User="gate", V4.11, 6 Channels, Priority=0
TCP 172.23.194.38:59307(cs03r-cs-serv-38.pri.diamond.ac.uk): User="epics_user", V4.11, 12 Channels, Priority=0
TCP 172.23.194.201:38553(cs03r-cs-gate-01.cs.diamond.ac.uk): User="gate", V4.11, 18 Channels, Priority=0
TCP 172.23.194.27:50143(cs03r-cs-serv-27.pri.diamond.ac.uk): User="archiver", V4.11, 1 Channels, Priority=20
TCP 172.23.194.28:52559(cs03r-cs-serv-28.pri.diamond.ac.uk): User="archiver", V4.11, 1 Channels, Priority=20


Very odd.  Any thoughts?

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Replies:
Re: Runaway connection count on IOC Andrew Johnson
RE: Runaway connection count on IOC Hill, Jeff

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