[omniORB] Missing Object Reference

[Sai-Lai Lo]

Dmitry,

I don't recall discovering any race condition related to object reference
counting between 2.6.1 and the current release.

One point you want to check is if you have implemented the loader hook
correctly. When your loader hook returns an object reference to the ORB,
the ORB consumes the object reference. In other words, it will call
release() on the object reference when it is done with it. Therefore you
should do a _duplicate() on the object reference before returning in your
loader hook.

Sai-Lai


>>>>> dmitry dolinsky writes:

> We are running to a problem with omniORB 2.6.1. The ORB throws an
> invalid object reference exception on a multiprocessor machine (
> Solaris2.7 ) running for several hours under heavy load. The exception
> was due to the fact that we try to _duplicate() or release() an object
> reference where the reference count was at zero. After spending a fair
> amount of time looking for missing _duplicate and race conditions in our
> code, we did not
> find the cause of the problem.
> Has anyone experienced anything similar? Could this be a bug in omniORB
> 2.6.1 perhaps fixed in a later version? (For a number of reasons we
> can't jump to a later version at this time, BTW). Any advice for
> tracking this down?
> Also, on a very rare occasion we are seeing an error that make us
> suspect that an operation is dispatched to wrong object. This does not
> happen as often as losing the object ref problem, but when this does
> happen, it
> happens at about the same time. We suspect that the two problems may be
> related.
> Here is some more information about what we do. We backported some
> patches for the scavenger from 2.8. Also, our objects persist in the
> database. A limited number of them is in memory at any given time. Those
> that are in
> memory are in the cache maintained by us. When a request for an object
> arrives that is not in memory, we load the object from database,
> register it with ORB, and add it to the cache possibly removing some
> other object
>> From the cache and deleting it (by calling _dispose()). This happens in
> omniORB::loader hook. Typically the problem manifests itself when we are
> calling _dispose(). The object that we have in our cache has the
> reference
> count of zero.

-- 
Sai-Lai Lo                                   S.Lo@uk.research.att.com
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