dspoolout

DSPOOLOUT(8)                System Manager's Manual               DSPOOLOUT(8)



NAME
       dspoolout - Diablo program to sequence and flush outbound queue files

SYNOPSIS
       dspoolout [ -q ] [ -v ] [ -n ] [ -s minutes ] [ -m maxrun ] [ -T
       txbufsize ] [ -R rxbufsize ] [ -B ip ] [ -f configfile ] [ label ]


DESCRIPTION
       DSpoolout reads the dnntpspool.ctl file and applies a sequence number
       to the outbound queue files maintained by diablo in the dqueue
       directory.  This involves renaming each queue file then running a dicmd
       to flush them.  DSpoolout is normally run from cron once every 5
       minutes.  The control file tells DSpoolout how many queue files to
       maintain for any given outbound feed and how many dnewslink processes
       to run in parallel for each outbound feed.  The default is 2, and may
       be changed by the -m maxrun option.  The dnewslink program itself is
       able to process multiple queue files in sequence, and judicious use of
       flock() prevents collisions when multiple processes are run on the same
       range of sequence numbers.  DSpoolout manages the whole affair.
       DSpoolout can also run smart based on whether the feeds are able to
       stay caught up.  The -s minutes option tells DSpoolout how often to
       sequence out a new outbound queue file and (potentially) run more
       dnewslinks when the feed is unable to stay caught up with our queue
       files.  If the feed is able to stay caught up, the option is ignored
       and DSpoolout attempts to handle the feed every time it is run.  This
       allows you to reduce the requeueing latency between incoming and
       outgoing feeds for those feeds able to handle your article rate without
       overloading the machine when you have many feeds.

       The -B option causes DSpoolout to pass the specified IP address to
       dnewslink, specifying the local address to be used for all outbound
       NNTP sessions.

       The -n option causes dspoolout to flush and rotate the queue files
       without executing any dnewslink's.

       An optional queue label may be specified to restrict dspoolout's
       operation to a single entry.  Otherwise, all entries are run.

       -f configfile Specify a configuration file other then dspoolout.ctl.
       If the configuration file is not an absolute path, diablo's news home
       is prepended to it.

       The -T and -R options set the transmit and receive TCP buffer size for
       dnewslink.  The defaults are usually ok, but if you want to be frugal
       you can usually reduce the receive buffer size without blowing the
       efficiency.

       It is suggested, however, that you run DSpoolout from cron no more then
       once every 5 minutes.  Heavy backbone transit points with lots of cpu
       cycles can get away with running DSpoolout every 2 minutes if they
       really want to, in which case the -s option really comes in handy.  A
       typical news path of 8 elements will propogate in 5x8 = 40 minutes with
       a 5 minute queue run, and 16 minutes with a 2 minute queue run.

       Many people proscribe real-time feeds.  Diablo tries to avoid real-time
       feeds for two reasons:  First, they add complexity to the main server
       and the additional system calls slow it down.  Second, real time feeds
       can lead to a false sense of security and efficiency.  While it is true
       that a real-time feed will make better use of the kernel file cache
       then a queued feed, very few news servers can dependably rely on this
       to maintain their feed rates... they MUST be designed to handle article
       delays and failures.  A server running too close to the edge will
       experience a NASTY cascade failure if it relies on the efficiency of
       the real time feed to maintain the article feed rate.


REALTIME FEEDS
       DSpoolout is capable of maintaining a dnewslink on designated realtime
       feeds.  A feed is specified as being realtime by using the 'realtime'
       option in the dnntpspool.ctl file (see the sample dnntpspool.ctl file).
       This is really only a near-real-time capability, since Diablo buffer's
       writes to outgoing queue files.  For a nominal full feed, the delay is
       approximately 5 seconds.

       The way it works is as follows:  dspoolout starts a dnewslink with the
       -r option on the active outgoing feed file.  DSpoolout also operates
       normally, attempting to start dnewslinks on any existing queue files up
       to a specified limit.  When dspoolout is next run, it flushes and
       rotates as per normal.  The dnewslink -r sitting on the active file
       will get it renamed out from under.  It detects this condition and
       closes/reopens the new active file as well as aattempts to remove the
       old one if it has finished processing it and no errors occured.


SEE ALSO
       diablo(8), dicmd(8), didump(8), diload(8), dnewslink(8), doutq(8),
       dexpire(8), dexpireover(8), diconvhist(8), dilookup(8), dspoolout(8),
       dkp(8), dpath(8), diablo-kp(5), diablo-files(5)

                                                                  DSPOOLOUT(8)