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Posted to users@openjpa.apache.org by Andrei Tchijov <an...@tchijov.com> on 2009/03/17 13:45:55 UTC
Strange "ClassCast" Exception (and even stranger way it disappear)
Out of blue, I started to get following exception:
http://n2.nabble.com/file/n2491173/ClassCastException.txt
ClassCastException.txt .
To the best of my understanding, problem occur when I am trying to access
@OneToMany field defined as following:
@OneToMany( mappedBy = "object", cascade = ALL )
@MapKey(name = "name")
private Map<String,PLSRelationship> relationships;
What was particularly weird, I have quite a few objects in the data base and
this exception was happening only when I was trying to access particular 2
of these objects. It was quite persistent too. It always was happening
when I was trying to access these 2 particular objects.
I was trying to figure out what was so special about these 2 objects and the
only thing I could see was that "@Version" field in records representing one
of PLSRelationship "related" to objects which were giving me an exception
were non null ( it was "1" ). On the wimp, I have reset value of all
"@Version" fields to null and now it works without any problems.
I would greatly appreciate if some one can shade some light on this issue.
Obviously, I am doing something wrong and manage to get my data base into
state which OpenJPA did not like much. The problem is that I have no idea
what exactly I did wrong (and how to prevent it from happening).
You comments will be highly appreciated,
Andrei
P.S. I am running OpenJPA 1.2.0 with mySQL. All classes are enchanted
during build time (using ant task).
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Re: Strange "ClassCast" Exception (and even stranger way it
disappear)
Posted by Andrei Tchijov <an...@tchijov.com>.
Sorry, I have wrote this e-mail fist thing in the morning before I
got my cup of coffee.
Maybe this is a solution to all OpenJPA problems? We should Enchant
entities instead of Enhancing them. It works in WoW :)
On Mar 17, 2009, at 10:44 , Kevin Sutter (via Nabble) wrote:
> Couldn't resist... :-)
>
> On Tue, Mar 17, 2009 at 7:45 AM, Andrei Tchijov <an...@...> wrote:
>
> >
> > P.S. I am running OpenJPA 1.2.0 with mySQL. All classes are
> enchanted
> > during build time (using ant task).
>
>
> Enchanted? I love it! I know you meant "enhanced" (instead of
> "enchanted"), but I think I like the idea of enchanting the Entities
> even
> better than enhancing the Entities. :-) Now, if these mailing
> lists could
> embed a little picture of a wizard or something, then this reply
> would be
> complete. Thanks for the laugh.
>
> Kevin
>
>
> >
> > --
> > View this message in context:
> > http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2491173.html
> > Sent from the OpenJPA Users mailing list archive at Nabble.com.
> >
> >
>
>
> This email is a reply to your post @ http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2491771.html
> You can reply by email or by visting the link above.
>
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Re: Strange "ClassCast" Exception (and even stranger way it
disappear)
Posted by Kevin Sutter <kw...@gmail.com>.
Couldn't resist... :-)
On Tue, Mar 17, 2009 at 7:45 AM, Andrei Tchijov <an...@tchijov.com> wrote:
>
> P.S. I am running OpenJPA 1.2.0 with mySQL. All classes are enchanted
> during build time (using ant task).
Enchanted? I love it! I know you meant "enhanced" (instead of
"enchanted"), but I think I like the idea of enchanting the Entities even
better than enhancing the Entities. :-) Now, if these mailing lists could
embed a little picture of a wizard or something, then this reply would be
complete. Thanks for the laugh.
Kevin
>
> --
> View this message in context:
> http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2491173.html
> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>
>
Re: Strange "ClassCast" Exception (and even stranger way it disappear)
Posted by Andrei Tchijov <an...@tchijov.com>.
I have stopped my application, opened mysql and used "UPDATE ..." to
set appropriate columns to "null".
I do have "@ManyToOne" defined like this
@ManyToOne
private PLSObject object;
On Mar 17, 2009, at 10:50 , Michael Dick wrote:
> Hi Andrei
>
> What do you mean by reseting the version field to null?
>
> The application should not update the version field (nor should it
> need to).
> OpenJPA will update the version for you automatically, if the
> application is
> calling setVersion(1) then that could cause problems. Off the top of
> my head
> I don't think it would manifest as a ClassCastException though.
>
> Do you have the corresponding @ManyToOne annotation on
> PLSRelationship?
>
> -mike
>
>
> On Tue, Mar 17, 2009 at 7:45 AM, Andrei Tchijov <an...@tchijov.com>
> wrote:
>
>>
>> Out of blue, I started to get following exception:
>> http://n2.nabble.com/file/n2491173/ClassCastException.txt
>> ClassCastException.txt .
>>
>> To the best of my understanding, problem occur when I am trying to
>> access
>> @OneToMany field defined as following:
>>
>> @OneToMany( mappedBy = "object", cascade = ALL )
>> @MapKey(name = "name")
>> private Map<String,PLSRelationship> relationships;
>>
>>
>> What was particularly weird, I have quite a few objects in the data
>> base
>> and
>> this exception was happening only when I was trying to access
>> particular 2
>> of these objects. It was quite persistent too. It always was
>> happening
>> when I was trying to access these 2 particular objects.
>>
>> I was trying to figure out what was so special about these 2
>> objects and
>> the
>> only thing I could see was that "@Version" field in records
>> representing
>> one
>> of PLSRelationship "related" to objects which were giving me an
>> exception
>> were non null ( it was "1" ). On the wimp, I have reset value of all
>> "@Version" fields to null and now it works without any problems.
>>
>> I would greatly appreciate if some one can shade some light on this
>> issue.
>> Obviously, I am doing something wrong and manage to get my data
>> base into
>> state which OpenJPA did not like much. The problem is that I have
>> no idea
>> what exactly I did wrong (and how to prevent it from happening).
>>
>> You comments will be highly appreciated,
>>
>> Andrei
>>
>> P.S. I am running OpenJPA 1.2.0 with mySQL. All classes are
>> enchanted
>> during build time (using ant task).
>> --
>> View this message in context:
>> http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2491173.html
>> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>>
>>
Re: Strange "ClassCast" Exception (and even stranger way it
disappear)
Posted by Michael Dick <mi...@gmail.com>.
Hi Andrei
What do you mean by reseting the version field to null?
The application should not update the version field (nor should it need to).
OpenJPA will update the version for you automatically, if the application is
calling setVersion(1) then that could cause problems. Off the top of my head
I don't think it would manifest as a ClassCastException though.
Do you have the corresponding @ManyToOne annotation on PLSRelationship?
-mike
On Tue, Mar 17, 2009 at 7:45 AM, Andrei Tchijov <an...@tchijov.com> wrote:
>
> Out of blue, I started to get following exception:
> http://n2.nabble.com/file/n2491173/ClassCastException.txt
> ClassCastException.txt .
>
> To the best of my understanding, problem occur when I am trying to access
> @OneToMany field defined as following:
>
> @OneToMany( mappedBy = "object", cascade = ALL )
> @MapKey(name = "name")
> private Map<String,PLSRelationship> relationships;
>
>
> What was particularly weird, I have quite a few objects in the data base
> and
> this exception was happening only when I was trying to access particular 2
> of these objects. It was quite persistent too. It always was happening
> when I was trying to access these 2 particular objects.
>
> I was trying to figure out what was so special about these 2 objects and
> the
> only thing I could see was that "@Version" field in records representing
> one
> of PLSRelationship "related" to objects which were giving me an exception
> were non null ( it was "1" ). On the wimp, I have reset value of all
> "@Version" fields to null and now it works without any problems.
>
> I would greatly appreciate if some one can shade some light on this issue.
> Obviously, I am doing something wrong and manage to get my data base into
> state which OpenJPA did not like much. The problem is that I have no idea
> what exactly I did wrong (and how to prevent it from happening).
>
> You comments will be highly appreciated,
>
> Andrei
>
> P.S. I am running OpenJPA 1.2.0 with mySQL. All classes are enchanted
> during build time (using ant task).
> --
> View this message in context:
> http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2491173.html
> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>
>
Re: It is getting out of hands!!!
Posted by Andrei Tchijov <an...@tchijov.com>.
Sorry for delay. I will try to reduce my code to manageable test
case. Unfortunately I can not promise that I will be able to do it
any time soon. Things are working without @Version and I have to spend
my time on other things.
I will try to rebuild our stuff with 1.2.1 and see if the problem went
away.
Thanks for your time.
Andrei
On Mar 18, 2009, at 15:14 , Kevin Sutter wrote:
> Andrei,
> I'm sorry you are experiencing issues with your scenario. But, we
> will
> probably need additional information to help decipher the problem.
> We have
> many, many testcases that use @Version in the Entities. And, 95% of
> our
> testing is with enhanced Entities (either statically or
> dynamically). So,
> my guess is that there's something unique with your particular
> scenario.
>
> In the previous string of notes, you had provided a snippet of
> code. Can
> you provide a failing example or testcase that demonstrates the
> problem? We
> just need something more to go off to determine the source of the
> problem.
>
> Thanks,
> Kevin
>
> On Tue, Mar 17, 2009 at 11:59 AM, Andrei Tchijov
> <an...@tchijov.com> wrote:
>
>>
>> Somehow DB got into this situation again (identical stack traces). I
>> end-up
>> removing (commenting out) @Version field from PSLBase class and now
>> it
>> works
>> (without any changes to DB).
>>
>> I think it points quite conclusively that something is not right
>> with the
>> way @Version field influence enhanced code. I will be more then
>> happy to
>> admit that I am doing something wrong, but I would like to know what
>> exactly
>> I am doing wrong.
>>
>>
>> Andrei
>> --
>> View this message in context:
>> http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2492567.html
>> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>>
>>
Re: It is getting out of hands!!!
Posted by Kevin Sutter <kw...@gmail.com>.
Andrei,
I'm sorry you are experiencing issues with your scenario. But, we will
probably need additional information to help decipher the problem. We have
many, many testcases that use @Version in the Entities. And, 95% of our
testing is with enhanced Entities (either statically or dynamically). So,
my guess is that there's something unique with your particular scenario.
In the previous string of notes, you had provided a snippet of code. Can
you provide a failing example or testcase that demonstrates the problem? We
just need something more to go off to determine the source of the problem.
Thanks,
Kevin
On Tue, Mar 17, 2009 at 11:59 AM, Andrei Tchijov <an...@tchijov.com> wrote:
>
> Somehow DB got into this situation again (identical stack traces). I
> end-up
> removing (commenting out) @Version field from PSLBase class and now it
> works
> (without any changes to DB).
>
> I think it points quite conclusively that something is not right with the
> way @Version field influence enhanced code. I will be more then happy to
> admit that I am doing something wrong, but I would like to know what
> exactly
> I am doing wrong.
>
>
> Andrei
> --
> View this message in context:
> http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2492567.html
> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>
>
It is getting out of hands!!!
Posted by Andrei Tchijov <an...@tchijov.com>.
Somehow DB got into this situation again (identical stack traces). I end-up
removing (commenting out) @Version field from PSLBase class and now it works
(without any changes to DB).
I think it points quite conclusively that something is not right with the
way @Version field influence enhanced code. I will be more then happy to
admit that I am doing something wrong, but I would like to know what exactly
I am doing wrong.
Andrei
--
View this message in context: http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2492567.html
Sent from the OpenJPA Users mailing list archive at Nabble.com.
Re: Strange "ClassCast" Exception (and even stranger way it
disappear)
Posted by Andrei Tchijov <an...@tchijov.com>.
I am looking at the snippet of code I have created and I start to wonder if
PLSEntity should be decorated with @MappedSuperclass instead of @Entity.
Could it be the reason for all this shenanigans?
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Re: Strange "ClassCast" Exception (and even stranger way it
disappear)
Posted by Andrei Tchijov <an...@tchijov.com>.
It looks like e-mail did not get my attachment. Here it is
http://n2.nabble.com/file/n2492089/PLSClasses.txt PLSClasses.txt
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Re: Strange "ClassCast" Exception (and even stranger way it
disappear)
Posted by Andrei Tchijov <an...@tchijov.com>.
See below:
On Mar 17, 2009, at 11:07 , Kevin Sutter (via Nabble) wrote:
> Andrei,
> More questions than answers, but let's see where this takes us...
>
> On Tue, Mar 17, 2009 at 7:45 AM, Andrei Tchijov <an...@...> wrote:
>
> >
> > Out of blue, I started to get following exception:
> > http://n2.nabble.com/file/n2491173/ClassCastException.txt
> > ClassCastException.txt .
> >
>
> Thanks for the call stacks. These do show that the
> ClassCastException is
> coming from one of the inserted methods due to the enhancement process
> (pcReplaceField). So, at least we know that the enhancement
> processing is
> taking place.
>
>
> > To the best of my understanding, problem occur when I am trying to
> access
> > @OneToMany field defined as following:
> >
> > @OneToMany( mappedBy = "object", cascade = ALL )
> > @MapKey(name = "name")
> > private Map<String,PLSRelationship> relationships;
>
>
> Is your "object" side of the relationship configured with a
> corresponding
> @ManyToOne? I can't see how this would manifest itself as a
> ClassCastException, but just checking.
>
Yes. There is corresponding "@ManyToOne"
@ManyToOne
private PLSObject object;
>
> >
> > What was particularly weird, I have quite a few objects in the
> data base
> > and
> > this exception was happening only when I was trying to access
> particular 2
> > of these objects. It was quite persistent too. It always was
> happening
> > when I was trying to access these 2 particular objects.
> >
> > I was trying to figure out what was so special about these 2
> objects and
> > the
> > only thing I could see was that "@Version" field in records
> representing
> > one
> > of PLSRelationship "related" to objects which were giving me an
> exception
> > were non null ( it was "1" ). On the wimp, I have reset value of all
> > "@Version" fields to null and now it works without any problems.
>
>
> Reset these fields via SQL direct to the database? You shouldn't be
> able to
> directly set the @Version field via your program. Here again, I'm not
> seeing the correlation to the ClassCastException...
I did reset it via SQL.
>
> Since you reset this Version field, I would assume that the Version
> field
> now has "valid" data in it? That is, each time the Entities get
> committed,
> the Version field should be incremented. Have you verified that the
> Version
> field seems to working as expected?
It seems to be working (numbers in this field do grow). I will need to
do some additional testing to see if it is really "+1" per-commit.
>
> Is there any chance that the definition of this Version field
> changed during
> this exercise? For example, maybe it was changed from a Timestamp
> to a
> Long? And, the contents of the database records for these two
> objects had
> an invalid value for the corresponding type? Just an idea.
No. This is how it looks from mySQL point of view
+--------------+--------------+------+-----+-------------------
+-----------------------------+
| Field | Type | Null | Key | Default |
Extra |
+--------------+--------------+------+-----+-------------------
+-----------------------------+
| ID | int(11) | NO | PRI | NULL
| |
| version | int(11) | YES | | NULL
| |
| created | timestamp | NO | | CURRENT_TIMESTAMP | on
update CURRENT_TIMESTAMP |
| owner_ID | int(11) | NO | | NULL
| |
| DTYPE | int(11) | NO | | NULL
| |
| name | varchar(256) | NO | | NULL
| |
| className | varchar(256) | YES | | NULL
| |
| container_ID | int(11) | YES | | NULL
| |
| object_ID | int(11) | YES | MUL | NULL
| |
| flags | int(11) | YES | | 0
| |
+--------------+--------------+------+-----+-------------------
+-----------------------------+
and this is how it is defined in Java
@SuppressWarnings("unused")
@Version
private int version;
I do not know if it is relevant, but I have 2 classes mapped into the
same table ( they both subclasses of the same class ). PLSRelationship
is one of these classes and another class ( PLSObject ) is the one
which contains "@ManyToOne" field which seems to be a problem.
I have attached to this e-mail snippet of code which combines extracts
from all relevant classes
>
> I'm stating the obvious here, but ClassCastExceptions normally
> happen due to
> incorrect ClassLoaders being used. Either the Class is not
> available, or a
> different ClassLoader was used for a given instance of the Class.
> Since we
> seem to tripping over the Version field, we're probably attempting
> to load
> the instance data for comparison purposes and then hit the
> ClassCastException.
The problem is that the very same code used to deal with many objects
of the same class. And exception only gets thrown on very few (and
once it start happening, always the same) of them
I do have copy of DB with "bad" versions. If you can think of any
additional tests, I can try to run them.
>
> Any of these ideas help with narrowing down the problem?
>
> Kevin
>
>
> >
> > I would greatly appreciate if some one can shade some light on
> this issue.
> > Obviously, I am doing something wrong and manage to get my data
> base into
> > state which OpenJPA did not like much. The problem is that I have
> no idea
> > what exactly I did wrong (and how to prevent it from happening).
> >
> > You comments will be highly appreciated,
> >
> > Andrei
> >
> > P.S. I am running OpenJPA 1.2.0 with mySQL. All classes are
> enchanted
> > during build time (using ant task).
> > --
> > View this message in context:
> > http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2491173.html
> > Sent from the OpenJPA Users mailing list archive at Nabble.com.
> >
> >
>
>
> This email is a reply to your post @ http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2491894.html
> You can reply by email or by visting the link above.
>
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Re: Strange "ClassCast" Exception (and even stranger way it
disappear)
Posted by Kevin Sutter <kw...@gmail.com>.
Andrei,
More questions than answers, but let's see where this takes us...
On Tue, Mar 17, 2009 at 7:45 AM, Andrei Tchijov <an...@tchijov.com> wrote:
>
> Out of blue, I started to get following exception:
> http://n2.nabble.com/file/n2491173/ClassCastException.txt
> ClassCastException.txt .
>
Thanks for the call stacks. These do show that the ClassCastException is
coming from one of the inserted methods due to the enhancement process
(pcReplaceField). So, at least we know that the enhancement processing is
taking place.
> To the best of my understanding, problem occur when I am trying to access
> @OneToMany field defined as following:
>
> @OneToMany( mappedBy = "object", cascade = ALL )
> @MapKey(name = "name")
> private Map<String,PLSRelationship> relationships;
Is your "object" side of the relationship configured with a corresponding
@ManyToOne? I can't see how this would manifest itself as a
ClassCastException, but just checking.
>
> What was particularly weird, I have quite a few objects in the data base
> and
> this exception was happening only when I was trying to access particular 2
> of these objects. It was quite persistent too. It always was happening
> when I was trying to access these 2 particular objects.
>
> I was trying to figure out what was so special about these 2 objects and
> the
> only thing I could see was that "@Version" field in records representing
> one
> of PLSRelationship "related" to objects which were giving me an exception
> were non null ( it was "1" ). On the wimp, I have reset value of all
> "@Version" fields to null and now it works without any problems.
Reset these fields via SQL direct to the database? You shouldn't be able to
directly set the @Version field via your program. Here again, I'm not
seeing the correlation to the ClassCastException...
Since you reset this Version field, I would assume that the Version field
now has "valid" data in it? That is, each time the Entities get committed,
the Version field should be incremented. Have you verified that the Version
field seems to working as expected?
Is there any chance that the definition of this Version field changed during
this exercise? For example, maybe it was changed from a Timestamp to a
Long? And, the contents of the database records for these two objects had
an invalid value for the corresponding type? Just an idea.
I'm stating the obvious here, but ClassCastExceptions normally happen due to
incorrect ClassLoaders being used. Either the Class is not available, or a
different ClassLoader was used for a given instance of the Class. Since we
seem to tripping over the Version field, we're probably attempting to load
the instance data for comparison purposes and then hit the
ClassCastException.
Any of these ideas help with narrowing down the problem?
Kevin
>
> I would greatly appreciate if some one can shade some light on this issue.
> Obviously, I am doing something wrong and manage to get my data base into
> state which OpenJPA did not like much. The problem is that I have no idea
> what exactly I did wrong (and how to prevent it from happening).
>
> You comments will be highly appreciated,
>
> Andrei
>
> P.S. I am running OpenJPA 1.2.0 with mySQL. All classes are enchanted
> during build time (using ant task).
> --
> View this message in context:
> http://n2.nabble.com/Strange-%22ClassCast%22-Exception-%28and-even-stranger-way-it-disappear%29-tp2491173p2491173.html
> Sent from the OpenJPA Users mailing list archive at Nabble.com.
>
>