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From: "Fitzgibbons, Brad" <bfitzgibbons@techtarget.com>
To: "users@jackrabbit.apache.org" <users@jackrabbit.apache.org>
Date: Wed, 16 Jul 2008 08:13:57 -0400
Subject: RE: RowIterator.next() fails when hasNext() returns true
Thread-Topic: RowIterator.next() fails when hasNext() returns true
Thread-Index: AcjnJLs0/EME44TGRPCQBZRrAJjuFwAGCz7Q
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I'll try to find some time to spin something up, but it's likely to be awhi=
le before I can find the bandwidth to do so.  As soon as I can I'll submit =
a repeatable, non-proprietary example of the problem.

As an aside, I've thoroughly enjoyed working with the JCR standard and Jack=
rabbit.  Thanks for all the work you and others have put into this.

brad

-----Original Message-----
From: Marcel Reutegger [mailto:marcel.reutegger@gmx.net]
Sent: Wednesday, July 16, 2008 5:16 AM
To: users@jackrabbit.apache.org
Subject: Re: RowIterator.next() fails when hasNext() returns true

Hi Brad,

are you able to extract this into simple test program without dependencies =
to your application? that would be great.

regards
  marcel

Fitzgibbons, Brad wrote:
> Yes, it's threadsafe.  Each visit to the URL invokes the resourceQueryAnd=
Print() method.  This method is wrapped in a JTA transaction, and results i=
n the following actions:
>     (1) Execute a new SQL query on the JCR session (using spring-modules =
to provide session).
>     (2) Create a new instance of PropertyIterator which wraps the RowIter=
ator from the query.
>     (3) Perform the loop as shown and print some of the metadata from eac=
h element in the result set.
>         (a) Each call to PropertyIterator.hasNext() delegates to RowItera=
tor.hasNext().
>         (a) Each call to PropertyIterator.next() will marshall data from =
the Row returned by RowIterator.next() into a DTO.
>
> Here's an example of the SQL query (with actual property names and node p=
rimary type changed):
>     select A,B,C,D from custom_type where (A=3D'A1' or A=3D'A2' or A=3D'A=
3')
> and (contains(B, 'XXX') or contains(C, 'XXX')) order by D
>
> Changing the properties in the select clause or the order by clause (but =
leaving the where clause as-is) will sometimes produce iterators that do no=
t have the hasNext/next behavior I've described.
>
>
> -----Original Message-----
> From: Marcel Reutegger [mailto:marcel.reutegger@gmx.net]
> Sent: Monday, July 14, 2008 8:40 AM
> To: users@jackrabbit.apache.org
> Subject: Re: RowIterator.next() fails when hasNext() returns true
>
> Hi,
>
> hmm, let's check something else... what about your class ProfileControlle=
r, is it thread-safe? is it possible that two threads concurrently call has=
Next/next?
> is PropertyIterator in ProfileController an instance variable?
>
> regards
>   marcel
>
> Fitzgibbons, Brad wrote:
>> Yes.  My loop breaks down to this:
>>
>> while (iterator.hasNext()) {
>>    Object obj =3D iterator.next();
>>    ...
>> }
>>
>> However, if I do this instead I get (what appears to be) "normal" behavi=
or (except that getSize() is often much less than the actual result set siz=
e):
>>
>> while (iterator.hasNext()) {
>>     try {
>>         Object obj =3D iterator.next();
>>     } catch (NoSuchElementException excp) { /* masked */ } }
>>
>> Thanks!
>> brad
>>
>> -----Original Message-----
>> From: Marcel Reutegger [mailto:marcel.reutegger@gmx.net]
>> Sent: Monday, July 14, 2008 4:35 AM
>> To: users@jackrabbit.apache.org
>> Subject: Re: RowIterator.next() fails when hasNext() returns true
>>
>> Hi,
>>
>> this seems very strange because LazyScoreNodeIterator always pre-fetches=
 the next node. so whenever you call hasNext() and it returns true LazyScor=
eNodeIterator already has the next node and does not have to fetch it on ne=
xtRow().
>>
>> Can you please double check that you always call hasNext() before you
>> call
>> nextRow() ?
>>
>> regards
>>   marcel
>>
>> Fitzgibbons, Brad wrote:
>>> I'm running into this problem occasionally resulting in the
>>> exception below.  I'm using Jackrabbit 1.4 (with core at 1.4.2).
>>> I'm using the H2PersistenceManager and almost all configuration
>>> values are set to their released default. Document order is turned
>>> off so the query is using a LazyScoreNodeIterator.  I'm running in a
>>> transactional environment, and my entire execution flow is contained
>>> by a single, read-only, JTA transaction.  The single transaction
>>> includes executing the query and all interactions with the returned
>>> RowIterator.  If I ignore the NoSuchElementException's and continue
>>> using the iterator then there are often good results subsequent to
>>> the error.  I've noticed that when these errors occur there are
>>> often far more results than are returned by RowIterator.getSize().
>>> I realize that getSize() is not meant to be an accurate count of all
>>> results, but in most other cases getSize() is greater than the size
>>> of the result set (this may not be helpful).  I'm using
>>  a SQL query that involves the CONTAINS constraint (so lucene) and order=
ing by jcr:score.  Does this warrant a bug submission?  Is there any additi=
onal information which might help?
>>> org.springframework.web.util.NestedServletException: Request processing=
 failed; nested exception is java.util.NoSuchElementException
>>>         at org.springframework.web.servlet.FrameworkServlet.processRequ=
est(FrameworkServlet.java:535)
>>>         at org.springframework.web.servlet.FrameworkServlet.doGet(Frame=
workServlet.java:453)
>>>         at javax.servlet.http.HttpServlet.service(HttpServlet.java:114)
>>>         at javax.servlet.http.HttpServlet.service(HttpServlet.java:91)
>>>         at com.caucho.server.dispatch.ServletFilterChain.doFilter(Servl=
etFilterChain.java:103)
>>>         at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFi=
lterChain.java:181)
>>>         at com.caucho.server.dispatch.ServletInvocation.service(Servlet=
Invocation.java:266)
>>>         at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest=
.java:269)
>>>         at com.caucho.server.port.TcpConnection.run(TcpConnection.java:=
603)
>>>         at com.caucho.util.ThreadPool$Item.runTasks(ThreadPool.java:721=
)
>>>         at com.caucho.util.ThreadPool$Item.run(ThreadPool.java:643)
>>>         at java.lang.Thread.run(Thread.java:619)
>>> Caused by: java.util.NoSuchElementException
>>>         at org.apache.jackrabbit.core.query.lucene.QueryResultImpl$Lazy=
ScoreNodeIterator.getScore(QueryResultImpl.java:351)
>>>         at org.apache.jackrabbit.core.query.lucene.RowIteratorImpl.next=
Row(RowIteratorImpl.java:153)
>>>         at com.techtarget.content.data.jcr1.ElementDaoImpl.nextElement(=
ElementDaoImpl.java:722)
>>>         at com.techtarget.content.data.jcr1.PropertyIterator.next(Prope=
rtyIterator.java:47)
>>>         at com.techtarget.content.data.jcr1.PropertyIterator.next(Prope=
rtyIterator.java:21)
>>>         at com.techtarget.content.web.controller.ProfileController.reso=
urceQueryAndPrint(ProfileController.java:125)
>>>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>>>         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAcce=
ssorImpl.java:39)
>>>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMe=
thodAccessorImpl.java:25)
>>>         at java.lang.reflect.Method.invoke(Method.java:597)
>>>         at org.springframework.web.bind.annotation.support.HandlerMetho=
dInvoker.doInvokeMethod(HandlerMethodInvoker.java:305)
>>>         at org.springframework.web.bind.annotation.support.HandlerMetho=
dInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:131)
>>>         at org.springframework.web.servlet.mvc.annotation.AnnotationMet=
hodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:3=
08)
>>>         at org.springframework.web.servlet.mvc.annotation.AnnotationMet=
hodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:295)
>>>         at org.springframework.web.servlet.DispatcherServlet.doDispatch=
(DispatcherServlet.java:874)
>>>         at org.springframework.web.servlet.DispatcherServlet.doService(=
DispatcherServlet.java:808)
>>>         at org.springframework.web.servlet.FrameworkServlet.processRequ=
est(FrameworkServlet.java:523)
>>>         at org.springframework.web.servlet.FrameworkServlet.doGet(Frame=
workServlet.java:453)
>>>         at javax.servlet.http.HttpServlet.service(HttpServlet.java:114)
>>>         at javax.servlet.http.HttpServlet.service(HttpServlet.java:91)
>>>         at com.caucho.server.dispatch.ServletFilterChain.doFilter(Servl=
etFilterChain.java:103)
>>>         at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFi=
lterChain.java:181)
>>>         at com.caucho.server.dispatch.ServletInvocation.service(Servlet=
Invocation.java:266)
>>>         at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest=
.java:269)
>>>         at com.caucho.server.port.TcpConnection.run(TcpConnection.java:=
603)
>>>         at com.caucho.util.ThreadPool$Item.runTasks(ThreadPool.java:721=
)
>>>         at com.caucho.util.ThreadPool$Item.run(ThreadPool.java:643)
>>>         at java.lang.Thread.run(Thread.java:619)
>>>
>>> Brad Fitzgibbons
>>> Senior Software Engineer
>>> Tech Target
>>> The Most Targeted IT Media
>>> http://www.techtarget.com/
>>>
>>>
>>>
>>
>
>