[Mailman-Users] running External Archiver on background/foreground

Mark Sapiro mark at msapiro.net
Fri Nov 30 19:37:06 CET 2007

Mohamed CHAARI wrote:
>I'm using Mailman for lists management, in a collaboration 
>infrastructure site.
>I configured Mailman so that an external archiver is used, but I 
>hesitate to run this archiver in background or foreground.
>More concretely, in mm_cfg.py conf file, should I put:
>PUBLIC_EXTERNAL_ARCHIVER = 'cat > /var/run/mailman/mail_tmp; 
>/usr/local/bin/external_arch %(listname)s'
>PUBLIC_EXTERNAL_ARCHIVER = 'cat > /var/run/mailman/mail_tmp; 
>/usr/local/bin/external_arch %(listname)s &'
>What do you recommend ? is there a difference, in terms of performance ?
>Is there a risk of system overload, for one of the 2 solutions, when 
>dealing with too big archives ? (I have some archives exceeding 50 M)

The size of the archive is only going to influence
/usr/local/bin/external_arch whatever that is. Its performance/run
time may or may not depend on the size of the archive.

There are potential issues either way (forground or background). The
external archiver command is run with the list locked. This is both
good and bad. It eliminates any potential race condition which might
overwrite /var/run/mailman/mail_tmp with a second message before the
first message is processed, at least if only one list is involved, but
it may keep the list locked for a long time if the external_arch
process is slow. In addition, if the external_arch shoud do something
that locks the list, a deadlock results.


Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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