[Zope] easy questions (1 zcatalog 1 zserver console?)

[Michel Pelletier]

"R. David Murray" wrote:
> 
> On Sun, 19 Mar 2000, alan runyan wrote:
> > 2000-03:20T03:24:27 ERROR(200) ZODB Couldn't load state for
> > '\000\000\000\000\000\000\350\217' <- this happens right before the
> > competing writes. could someone explain what this \xxx\yyy\zzz is?
> 
> I believe that is python's octal representation of an internal object
> index.  The 'could not load state' means the ZODB tried to load
> the object from disk storage and could not complete the operation.
> 
> I'm getting those on my own database and haven't yet had the time
> to track down where they are coming from.  I fear some sort of
> database corruption, but so far the system has continued to function
> despite these errors.

There error occours because there are pickles in your database that
cannot be loaded.  The 'persistent' information for an object in the
database is a 'pickle', or a serialized representation of the object. 
In order for the object be loaded into memory the pickle needs to be
unwound into an object in memory.

However, this serialized representation does *not* contain any active
code, it's just the state of the object.  In order for the object to
truely 'come to life' the pickle must be matched up with the python code
that all objects have in one way or another.

This error occours when the pickle can be read, but no coresponding
python code could be matched up with the object to bring it to life, or,
an error occoured while object was being unpickled.  Unfortunatly, there
aren't any better iagnostic tools to find why these pickles cannot be
unloaded, and for the most part they are now orphaned objects, you
cannot delete them or manage them or remove them from your database.

I can envision some kind of tool like fsck or scandisk that goes through
your database (probably offline) and lets you examine/purge/fix these
kinds of dead objects.  Ty Sarna has come up with an introspectio ntool
called the Tranalyser that would probably be a good place to start.

-Michel

> 
> --RDM
> 
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