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From "Joshua Hyde (Issue Comment Edited) (JIRA)" <j...@apache.org>
Subject [jira] [Issue Comment Edited] (JCR-2596) multiple instances of jackrabbit-standalone cause "file backing binary value not found" from org.apache.jackrabbit.util.TransientFileFactory
Date Fri, 04 Nov 2011 14:09:00 GMT

    [ https://issues.apache.org/jira/browse/JCR-2596?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13144039#comment-13144039
] 

Joshua Hyde edited comment on JCR-2596 at 11/4/11 2:07 PM:
-----------------------------------------------------------

I came here via JCR-2609, and we're seeing that issue on the IBM WAS JRE:

[{me} bin]# ./java -version
java version "1.6.0"
Java(TM) SE Runtime Environment (build pxa6460sr7ifix-20100220_02(SR7+IZ69890+IZ70326))
IBM J9 VM (build 2.4, JRE 1.6.0 IBM J9 2.4 Linux amd64-64 jvmxa6460sr7-20100219_54097 (JIT
enabled, AOT enabled)
J9VM - 20100219_054097
JIT  - r9_20091123_13891
GC   - 20100216_AA)
JCL  - 20091202_01

[ Edit: for sake of clarity, the affected application isn't JBoss CMS, as described in JCR-2609,
but an application of our own making sitting on top of JackRabbit, but the stacktraces look,
line-for-line, the same, and we do have multiple JackRabbit instances running on the same
physical box. ]
                
      was (Author: jrh3k5):
    I came here via JCR-2609, and we're seeing that issue on the IBM WAS JRE:

[{me} bin]# ./java -version
java version "1.6.0"
Java(TM) SE Runtime Environment (build pxa6460sr7ifix-20100220_02(SR7+IZ69890+IZ70326))
IBM J9 VM (build 2.4, JRE 1.6.0 IBM J9 2.4 Linux amd64-64 jvmxa6460sr7-20100219_54097 (JIT
enabled, AOT enabled)
J9VM - 20100219_054097
JIT  - r9_20091123_13891
GC   - 20100216_AA)
JCL  - 20091202_01
                  
> multiple instances of jackrabbit-standalone cause "file backing binary value not found"
from org.apache.jackrabbit.util.TransientFileFactory
> --------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: JCR-2596
>                 URL: https://issues.apache.org/jira/browse/JCR-2596
>             Project: Jackrabbit Content Repository
>          Issue Type: Bug
>          Components: jackrabbit-jcr-commons
>    Affects Versions: 2.0
>         Environment: any
>            Reporter: Adrien Lamoureux
>
> running 2 or more instances of jackrabbit-standalone causes file deletions in the temporary
folder used by another standalone instance. (when garbage collected)
> To reproduce, run 2 or more instances, create files in each, and then stop one of them
and attempt read cached files by the other. The one that stopped will garbage collect files
used by the other. This may be hard to reproduce, as it doesn't seem to be guaranteed to have
a collision on file names. The problem "went away" when I forced each instance to use a different
temporary folder. But this is not a permanent solution.
> Ex:
> java -Dhostname=standalonejcr -Djava.io.tmpdir=/tmp1 -Xmn100M -Xms500M -Xmx500M -jar
jackrabbit-standalone-2.0.0.jar -p 8000 -r jcr-repository 
> java -Dhostname=standalonejcr -Djava.io.tmpdir=/tmp2 -Xmn100M -Xms500M -Xmx500M -jar
jackrabbit-standalone-2.0.0.jar -p 8001 -r jcr-repository 
> Original Emails: (to jackrabbit dev mailing list)
> >>>>>>>>>>>
> Wed, Apr 7, 2010 at 11:21 AM
> subject	clustered environment, 2 different jvms, TransientFileFactory, storing file blobs
in db
> Hello,
> I would normally file a bug on jira, but its very difficult to setup/reproduce, so I'm
looking for insight first on how temp files/blobs are implemented in jackrabbit.
> We currently run 2 different "standalone" instances of jackrabbit version 2.0.0, each
in their own JVM and setup the same way in using <cluster>. 
> Our application connects to one of the standalone instances remotely(webdavex) for authoring
content, and sends publish instructions (via JMS/activemq) to the other.
> The problem though, is that BLOBInTempFile.getStream is occasionaly throwing : "file
backing binary value not found", and one of the instances sometimes can't read the file.
> I've searched and found this information:
> http://mail-archives.apache.org/mod_mbox//jackrabbit-dev/200603.mbox/<90a8d1c00603150237t4c81df4fx178fcd726a93fe@mail.gmail.com>
> So apparently, when files are read/written, you create a temporary cache, but TransientFileFactory
runs as a singleton within a single JVM correct?
> So can I assume that one of the "singletons", (there will be 2??) will delete files that
were created by the other at some DIFFERENT random time when the garbage collector runs?
> I've also attached your Repository.xml that we use for both (with different cluster ids
of course)
> Adrien
> Thanks
> Is there some way to avoid this??
> I've attached our repository.xml for you to look at, both are setup the same way for
e
> Thanks.
> >>>>>>>>>>>>
> from	Stefan Guggisberg 
> reply-to	dev@jackrabbit.apache.org
> to	dev@jackrabbit.apache.org
> date	Thu, Apr 8, 2010 at 12:59 AM
> subject	Re: clustered environment, 2 different jvms, TransientFileFactory, storing file
blobs in db
> On Wed, Apr 7, 2010 at 8:21 PM, Adrien Lamoureux
> wrote:
> > Hello,
> > I would normally file a bug on jira, but its very difficult to
> > setup/reproduce, so I'm looking for insight first on how temp files/blobs
> > are implemented in jackrabbit.
> > We currently run 2 different "standalone" instances of jackrabbit version
> > 2.0.0, each in their own JVM and setup the same way in using <cluster>.
> > Our application connects to one of the standalone instances
> > remotely(webdavex) for authoring content, and sends publish instructions
> > (via JMS/activemq) to the other.
> > The problem though, is that BLOBInTempFile.getStream is occasionaly throwing
> > : "file backing binary value not found", and one of the instances sometimes
> > can't read the file.
> > I've searched and found this information:
> > http://mail-archives.apache.org/mod_mbox//jackrabbit-dev/200603.mbox/<90a8d1c00603150237t4c81df4fx178fcd726a93fe@mail.gmail.com>
> > So apparently, when files are read/written, you create a temporary cache,
> > but TransientFileFactory runs as a singleton within a single JVM correct?
> yes
> > So can I assume that one of the "singletons", (there will be 2??) will
> > delete files that were created by the other at some DIFFERENT random time
> > when the garbage collector runs?
> no, unless java.io.File#createTempFile invoked from 2 different jvm's
> would create
> colliding temp files. but that's impossible according to the javadoc [0]:
> <quote>
> [...] is guaranteed that:
> 1. The file denoted by the returned abstract pathname did not exist
> before this method was invoked
> [...]
> </quote>
> cheers
> stefan
> [0] http://java.sun.com/javase/7/docs/api/java/io/File.html#createTempFile(java.lang.String,
> java.lang.String, java.io.File)
> >>>>>>>>>>>>
> from	Thomas Müller 
> reply-to	dev@jackrabbit.apache.org
> to	dev@jackrabbit.apache.org
> date	Thu, Apr 8, 2010 at 1:52 AM
> subject	Re: clustered environment, 2 different jvms, TransientFileFactory, storing file
blobs in db
> Hi,
> Stefan is right, File.createTempFile() doesn't generate colliding
> files. However, there is a potential problem with the
> TransientFileFactory. Consider the following case:
> - The file "bin-1.tmp" is created (BLOBInTempFile line 51).
> - The TransientFileFactory adds a PhantomReference "A" in its queue.
> - BLOBInTempFile.delete() or dispose() is called, the file "bin-1.tmp"
> is deleted.
> - A new file is created, and also called "bin-1.tmp" is created
> (BLOBInTempFile line 51)
>  (that's possible because File.createTempFile can re-use file names).
> - The TransientFileFactory adds a second PhantomReference "B" in its
> queue, pointing
>  to a different file with the same name.
> - The first (only the first) BLOBInTempFile is no longer referenced.
> - The TransientFileFactory.ReaperThread gets PhantomReference "A" and
>  deletes this file. But the file is still used and referenced ("B").
> I'm not sure if this is what is happening in your case, but it is a
> potential problem.
> Could you log a bug?
> There are multiple ways to solve the problem. I think the best
> solution is to not use File.createTempFile() and instead use our own
> file name factory (with a random part, and an counter part).
> Regards,
> Thomas

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