have you tried disabling the collection-desriptor tweaking in RelationshipPrefetcherImpl#prepareRelationshipSettings() ?
public void prepareRelationshipSettings()
{
setCascadeRetrieve(getObjectReferenceDescriptor().getCascadeRetrieve());
getObjectReferenceDescriptor().setCascadeRetrieve(false); // comment it
}jakob
John wrote:
I sensed that, but I'm not sure the penalty for loading an object twice is is bad as the penalty I was getting. A lot of places in our code assume the object reference is loaded on a required relationship. One thread was prefetching and turned off auto-retrieve, then another came in and thought that was the right value and set it back to that. So from then on none of the objects had the relationship loaded and I got NullPointerException everywhere.
I suppose that multiple loads could be more of an issue with the global cache, but with cache-per-broker I'm not sure if that's an issue. At least to me double-load isn't as big a deal as the NPE's. I had to discontinue using prefetch in the couple of places I was using it. (Not sure that's the worst thing anyway, since I don't know that it helped a whole lot.)
John
===== Original Message From Jakob Braeuchi <[EMAIL PROTECTED]> ===== hi john,
John wrote:
Has there been any solution to this issue (OJB188)? This bit me in the
butt,
but of course it took quite a bit of digging and debugging to realize this
is
what was happening. Why exactly is the value changed while prefetching?
auto-retrieve is disabled during prefetching of a relationship to avoid loading the same obj multiple times.
jakob
I have a patched version of OJB that was based on HEAD from the middle of
August, so I haven't been able to update for a while (don't want to
repatch).
It seems that there have been some changes to OJB since then with regards
to
(proxy) prefetching, autoretrieve, etc, especially in how those are
configured
in the repository. Are these summarized anywhere?
John Marshall Connectria
============================================= Date: Fri, 11 Jul 2003 18:19:33 +0200 From: Jakob Braeuchi <[EMAIL PROTECTED]> Subject: Potential problem with prefetch-relationships ? Content-Type: text/plain; charset=ISO-8859-1; format=flowed
hi theo,
during prefetch auto-retrieve is disabled. when an other thread uses the relationship-desriptor it will find auto-retrive off. this is a known problem but i do not have a solution for it :(
jakob
Theo Niemeijer wrote:
Hi all, I seemed to have stumbled on a potential problem with the "prefetch relationship" option in PB query.
After using prefetchRelationship for retrieval of big list of results, and at the same time performing other queries, I seemed to have lost the "auto-retrieve" attribute on the collection descriptor.
The result was that subsequent queries did not retrieve that collection anymore, probably because the "auto-retrieve" was disabled.
The problem is quite hard to reproduce, but my guess is that different threads modified the repository descriptor in the wrong sequence, by means of the setCascadeRetrieve method used in prepareRelationshipSettings.
I might be wrong, because I simply do not oversee all aspects of OJB. But am I right to view this as a potential problem in "concurrency situations" like websites ? I do not feel too comfortable that OJB makes these "temporary" changes to the repository model.
Cheers, Theo Niemeijer
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