Experimental Physics and
Industrial Control System

[email protected] · Wed, 01 Sep 1999 11:47:55 -0700 (PDT)

To people running portable CA servers:

Question:  I've recently added diagnostics to my CA server to keep track
           of the last 10 PVs broadcast to me that don't exist on my server.
           I also keep a counter of the number of times non-existent PVs 
	   are requested and the time of the last request.  I see I'm being 
           bombarded constantly with many PVs that belong on a totally 
           different control system (BaBar - and a different subnet).  So 
           there is a leak somewhere (probably the gateway).  Besides shutting
           down each client until the problem goes away, are there other
           less invasive techniques for finding "noisy" clients?  The server
           runs on a VMS system with Multinet (there may be some Multinet
           tool...).

Problem:   My server was freezing about once a week.  I tracked the problem
           down to a rare bad status return from the select call in the process
           function in the fdManager.cc file.  I have changed it so that 
           all fd sets are zeroed and return is done if there is ANY bad status 
           from select.  I have not seen the freeze since correcting this
           problem though I'll continue monitoring.  Here is a snippet with 
           the change for anyone interested:

	if (ioPending) {
		status = select (this->maxFD, &this->fdSets[fdrRead], 
			&this->fdSets[fdrWrite], &this->fdSets[fdrExcp], &tv);
	}
	else {
		status = 0;
	}

	if (waitPending) staticTimerQueue.process();

	if (status<=0) {
		for (size_t i=0u; 
		     i<sizeof(this->fdSets)/sizeof(this->fdSets[0u]); i++) {
			FD_ZERO(&this->fdSets[i]);
		}
		if ((status < 0) && (SOCKERRNO != SOCK_EINTR)) {
			fprintf(stderr, 
			"fdManager: select failed because errno=%d=\"%s\"\n",
				SOCKERRNO, SOCKERRSTR);
		}
		this->processInProg = 0;
		return;
	}

Thanks for your help!  Sorry I'm missing you all at ICALEPCS.

Stephanie Allison

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System