Xrd.sched ignored?

In the past we have defined xrd.sched on FSTs within /etc/xrd.cf.fst which successfully throttled the number of concurrent handler threads.

In recent version of xrootd (4.8.3 / 4.8.4) with Citrine 4.2.24 this no longer appears to take effect:

19:13:34 # grep xrd.sch /etc/xrd.cf.fst
xrd.sched mint 8 maxt 256 idle 60

19:14:12 # netstat -tonp | grep ESTABLISHED | grep xrootd | wc -l

This occurs with xrootd versions 4.8.3 and 4.8.4 from the xrootd-stable repo http://xrootd.org/binaries/stable/slc/6/x86_64/

xrd.sch appears supported in 4.8 per http://xrootd.org/doc/dev48/xrd_config.htm#_Toc496911324

No fd is open for the config file (expected?) though one is for the logfile

19:36:41 # ps aux | grep eos
daemon 3012 77.0 0.2 1104568 289620 ? SLl 19:36 0:16 /usr//bin/xrootd -n fst -c /etc/xrd.cf.fst -l /var/log/eos/xrdlog.fst -b -Rdaemon
daemon 3053 0.0 0.0 356808 47212 ? S 19:36 0:00 /usr//bin/xrootd -n fst -c /etc/xrd.cf.fst -l /var/log/eos/xrdlog.fst -b -Rdaemon

19:38:39 # lsof -p 3012 | grep xrdlog
xrootd 3012 daemon 2w REG 0,23 1030207319 384 /eos/log/fst/xrdlog.fst

19:38:49 # lsof -p 3012 | grep xrd.cf

Any ideas why xrd.sch seems be be ignored, or is there another method that should be used for such throttling at the FST?


Are we misinterpreting the use of the xrd.sched directive with eos with these versions of xrootd?

Can another site validate if this directive is honored or not?

Thank you,

Hey Pete,

Quick question. Is this only occurring on FST nodes or are you seeing the same behavior on the MGM nodes as well?

I might be able to give this a try. I’m running xroot 4.8.4-1 and EOS 4.2.28 on a few test nodes. I’ll let you know.

Dan Szkola

Hi Pete,
there are many more threads running in the EOS FST, not only the XRootD IO threads. You have to take a strack trace with GDB and have to count the one corresponding to the XRootD thread pool. There is already one thread per disk aso. … Cheers Andreas.

Hi Andreas,

Thanks for the input.

I enable xrootd summary monitoring on the FST’s /etc/xrd.cf.fst via

And started a listener on the mgm via: mpxstats -f flat -p 3333

I see that indeed the xrootd summary reported values for sched.threads does not exceed the values defined by xrd.sched, and link.num essentially matches the netstat connections:

So yep, the xrd.sched directive appears to be honored and I was merely counting the incorrect thing.

The xrootd summary monitoring is helpful, and looks good.

Thank you,

Thanks Dan, looks like I have it now.