On Apr 1, 2010, at 5:24 AM, Marc Guenther wrote:
Hi all,
I spent quite some time now on this problem. I found a way to
reproduce it, still I have no idea what to do about it.
Can you share what that is?
What I don't understand, if this is a known bug, and people are
actually experiencing it, why have I never heard about it, and why
is there no fix? This seems to be a major problem.
I also found, that this also happens on WO5.2.3, which makes it even
worse. I wonder why it has never bitten us before. Or maybe it has,
but now some customer discovered some peculiar workflow which
triggers this more often than usual.
I don't recall seeing anything like this for a long time. I suspect
that your customer theory may be true.
Chuck
James and Johann, (or everyone who has this problem), which version
of WO are you using? Are we all talking about 5.4.3 here?
On 25.03.2010, at 21:38, Mike Schrag wrote:
I don't have a patch you can easily apply. The workaround on your
side is to not let the EO in the parent EC garbage collect
(basically, keep a reference to the parent EO around for any EO
that you fault into child EC).
Would a parentEC.setRetainsRegisteredObjects(true) help?
Also there is a EODatabaseContext.disableSnapshotRefCounting()
method, which completely disabled the refcounting mechanism. But I
guess that would run out of memory very fast?
There's not an easy recovery from this -- you have to toss your EC
stack ... or .. maybe you could refetch the snapshot underneath it,
but i think you're probably left with a __retainCount of -1 at that
point, so probably even that won't help you.
No, I don't want this to occur at all :)
Have a happy easter,
Marc
I think this could be fixed pretty easily in wonder by overriding
ERXGenericRecord.__setRetainCount .. When count is set >0, call
back to your EC and retain the object in a dict and when it drops
to 0, release that ref.
On Mar 25, 2010, at 4:25 PM, Brook, James wrote:
Mike,
That sounds all too familiar to me. We are experiencing errors
just like that. We have a feature that creates nested editing
contexts several levels deep and fetches EOs all the way down to
the bottom. Do you know of a workaround, patch or some way to
recover from the bug you mention? I seem to remember a similar bug
years ago in the days when EOF kept strong references. We are
using Wonder.
Sorry for selfishly jumping in. Disappearing snapshots are causing
us lots of pain because whole instances of our application become
useless.
--
James
________________________________________
From: webobjects-dev-bounces
[email protected] [[email protected]
] On Behalf Of Mike Schrag [[email protected]]
Sent: 25 March 2010 20:20
To: Marc Guenther
Cc: [email protected]
Subject: Re: Snapshots mysteriously vanishing?
by any chance was this an EO in a parent editing context that
also existed in a child editingcontext?
I don't think so, but I'm not sure. That particular EO could have
been in all differents ECs at the time, as it's entity is used
all over the place.
Do you have anything specific in mind?
yeah, there's a bug with refcounting of eo's in child ec's if the
parent ec copy of the EO gets garbage collected ... the result of
this bug is disappearing snapshots. this specifically applies to
eo's fetched into a child that were already fetched into the
parent, though, not to peer ec's.
ms
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--
Chuck Hill Senior Consultant / VP Development
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems.
http://www.global-village.net/products/practical_webobjects
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