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Top Forums UNIX for Dummies Questions & Answers nohup has a terrible bad performance compared with interactive command, why? Post 302289552 by viniciov on Friday 20th of February 2009 12:19:35 AM
Old 02-20-2009
Question nohup has a terrible bad performance compared with interactive command, why?

I have a strange situation. I'm running a shell script containing several data uploads (using Oracle sqlloader utility). This script is being run on a Red Hat server.

I tried to run it in background:

$ nohup upload.sh &

This script uploads some thousands files. After several hours I checked what the nohup.out was showing and I was quite surprised to see it was very and extremely slow, because it just processed around less than a hundred files. Probably it would took more than 3 days to complete...

I ran the script interactively, I mean direct from command line showing output to screen. Surprise! the script ran several times better that when using nohup, finishing less than an hour.

I suspicted this was because the process using nohup has a slower priority than the one being run interactively. That was not true, both processes had the same priority.

Why this behaviour? I'm not a linux expert. Please help.

Thanks
 

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UP2DATE(8)							   Red Hat, Inc.							UP2DATE(8)

NAME
rhnsd - a program for quering the Red Hat Network for updates and information SYNOPSIS
rhnsd [OPTION]... DESCRIPTION
rhnsd is a daemon process that runs in the background and periodically polls the Red Hat Network to see if there are any queued actions available. If any are queued, it runs them. rhnsd is typically started from the init scripts in /etc/init.d/rhnsd when it's time to poll the Red Hat Network servers for available updates and actions. The default interval is every 120 minutes. The minimum polling interval is 60 minutes. To check for updates, rhnsd runs an external program called rhn_check. This is a small application that actually makes the network connec- tion to Red Hat Networks. The rhnsd daemon does not listen on any network ports, nor does it ever talk to the network directly. Any network activity is done via the rhn_check utility. rhnsd can be configure by editing the /etc/sysconfig/rhn/rhnsd config file. This is actually the configuration file the rhnsd init script /etc/init.d/rhnsd uses. -i, --interval Specify the interval that rhnsd should wait between checking the Red Hat Network. Default is 120 minutes, the minimum is 60 minutes. This can also be specified in /etc/sysconfig/rhn/rhnsd -v, --verbose output more information about what rhnsd is doing. -f, --foreground force the rhnds process to run in the foreground instead of automatically backgrounding itself, as it does by default. FILES /etc/sysconfig/rhn/rhnsd Configuration settings for the rhnsd daemons init script. /usr/sbin/rhn_check The external program launched by rhnsd to connect to the Red Hat Network and retrieve any actions that have queued up. /etc/sysconfig/rhn/systemid A certification that authenticates the client machine to the Red Hat Network. Generated via the up2date or rhnreg_ks utility. SEE ALSO
The rhnsd daemon is tightly coupled with Red Hat Network. Visit <http://www.redhat.com/network> for access or to sign up. rhn_check(8), up2date(8), up2date-config(8), AUTHORS
Written by Preston Brown <pbrown@redhat.com> and Cristian Gafton <gafton@redhat.com> REPORTING BUGS
Report bugs to <http://bugzilla.redhat.com>. COPYRIGHT
Copyright (C) 1999, 2000 Red Hat, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU- LAR PURPOSE. 4th Berkeley Distribution Fri Feb 9 2001 UP2DATE(8)
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