[Mailman-Developers] Is the config.pck.last logic correct?

[Barry Warsaw]

On Wed, 2004-02-04 at 14:09, Les Niles wrote:
> Our list server had another crash the other day, this time it
> really toasted a couple of lists. :(  (No, we hadn't yet done any
> of the mitigation steps that we should've, at least none that
> worked....)
> 
> What happens is that some of the config.pck files get trashed by
> having the last part of the file overwritten with nul bytes.  I'm
> assuming that it's a filesystem corruption causing this, perhaps
> involving disk hardware errors.  By the time the problem is
> apparent, the config.pck and config.pck.last files are both trashed
> -- they're identical, with identical timestamps.  I've looked at
> the logic for loading and saving config.pck, and don't see how this
> can happen.  It seems like config.pck.last gets replaced only when
> the list data is saved, which should only happen at some point
> after the list data is successfully loaded.  So there should be
> good data to generate the config.pck, otherwise config.pck.last
> should be left alone.  But there seems to be some flaw in the
> logic, that I can't see, because both files are ending up trashed.
> Then again, I've clearly demonstrated an overwhelming stupidity by
> letting these crashes happen many times until finally something
> really nasty occurred, so maybe I'm just too stupid to look at the
> code.
> 
> Or maybe something entirely different is happening.  If the
> pickle-save itself is corrupted in a way that isn't being caught,
> then I suppose the bad config.pck will happily by turned into an
> equally bad config.pck.last.
> 
> Obviously I don't have a reproducible test case for this, but maybe
> someone has some idea of what's going on, and how to improve the
> robustness. 

Have you tried setting SYNC_AFTER_WRITE=Yes in your mm_cfg.py file?

-Barry