Re: PAR + tmpwatch = mess

Hello Markus,

This looks like RT ticket 101800. 
https://rt.cpan.org/Public/Bug/Display.html?id=101800

I submitted a patch to implement the canary approach in that ticket, but 
it has not yet had a response.

It could do with some review, so maybe try that patch with your system 
and advise if it works or any modifications?

Regards,
Shawn.


On 13/05/2015 1:32, Markus Jansen wrote:
>
> Hi,
>
> on Linux, very often tmpwatch(8) is employed to clean /tmp and 
> /var/tmp periodically (on other systems, e.g. on Solaris 10,
>
> this is not the default) via cron.daily. Whether atime, mtime, or 
> ctime, or a combination of these stamps are used, is a matter of the 
> local configuration.
>
> Unfortunately, this results not in the removal of complete PAR 
> deployment trees in one of these directories, but to single files.
>
> As PAR restitutes the correct mtime after unpacking for most files, 
> functionality may “slowly deteriorate”, worst case depending
>
> on the mtime during packing the PAR executable.
>
> While long-term servers could apply quite some countermeasures (such 
> as using a different location, or periodically “refreshing” their PAR 
> cache),
>
> I fail to see an easy solution for “ordinary” client programs other 
> than setting PAR_CLEAN, thereby slowing startup down.
>
> IMHO the cleanest solution would be to provide tmpwatch with a sort of 
> “wipe all or nothing of a tree” marks.
>
> A possible PAR approach would be to unpack all files without setting 
> the mtime, except for a special “canary bird” file, which would be 
> artificially aged
>
> by a little more than a day. Removing the “canary bird” would then 
> invalidate the cache.
>
> Any opinions are highly appreciated.
>
> Best regards,
>
> Markus
>
> Ericsson <http://www.ericsson.com/>
>
> *MARKUS JANSEN Dipl.-Ing.*
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