rsync - May 2005 - multiple simultaneous instances of 'rsync'

Hi all,

   I have a perl-based program that creates lists of files to copy from 
A to B using rsync. The program can be told, when there is more than one 
copy list, to call rsync however many times simultaneously. This all 
works just fine to a point.

   The problem is that even though (in my test) two rsync processes have 
been called (check with 'ps ax | grep rsync') and in the end they both 
work they don't seem to run at the same time, which is my goal. the 
first one to be called runs and the second one seems to wait until the 
first one finishes before starting to copy it's list.

   Some info on my system:

- The test used three partitions on one physical disk under Debian Sarge 
with a 2.6.8 kernel. (Could the delay be because it's on the same disk?) 
All partitions are ext3.
- 'rsync' is: version 2.6.4 protocol version 29
Capabilities: 64-bit files, socketpairs, hard links, symlinks, 
batchfiles, inplace, IPv6, 64-bit system inums, 64-bit internal inums
- perl is: v5.8.4 built for i386-linux-thread-multi

   Thanks for any advice/tips!

Madison

-- 
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Madison Kelly (Digimer)
TLE-BU, The Linux Experience; Back Up
http://tle-bu.thelinuxexperience.com
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On Tue, May 17, 2005 at 11:15:50AM -0400, Madison Kelly
wrote:
> The problem is that even though (in my test) two rsync processes have 
> been called (check with 'ps ax | grep rsync') and in the end they
both
> work they don't seem to run at the same time, which is my goal.
Remember that the receiving side forks into two processes, I'd guess
that you're just be seeing a single run's two processes.  If so, you
need to fix how your script runs the commands at the same time (it needs
to fork(), use exec() to run rsync from the child process, use system()
to run rsync from the parent process, and then have the parent process
use waitpid() on the child pid to get its return status).

..wayne..