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multiple thread problem with EHCache

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drosenbaum

Post subject: multiple thread problem with EHCache

Posted: Fri Oct 29, 2004 2:43 pm

Regular

Joined: Tue Nov 11, 2003 7:35 pm
Posts: 63

Hibernate version: 2.1.6 and EHCache version 1.0

Hi All,

I seem to be having a multiple thread problem instantiating a cache. If multiple threads try to create a cache at the very same moment I get the following exception:

Code:

net.sf.hibernate.cache.CacheException: net.sf.ehcache.ObjectExistsException: Cache WhateverCache already exists

I think this would happen in general but specifially in my case it happens if I try to use a query cache in Hibernate. I am doing the following:

Code:

Query query = session.createQuery("some query"); 
query.setCacheable(true); 
query.setCacheRegion("WhateverCache"); 
return query.list(); 

if this block of code gets executed simultaniously by more than one thread it results in the exception.

The same session is NOT used for both threads, i.e. each thread has its own session.

Is this a bug in Hibernate or EHCache? Perhaps there needs to be some syncronization code somewhere.

Here is more of the stack trace:

Code:

net.sf.hibernate.cache.CacheException: net.sf.ehcache.ObjectExistsException: Cache WhateverCache already exists 
at net.sf.hibernate.cache.EhCache.<init>(EhCache.java:101) 
at net.sf.hibernate.cache.EhCacheProvider.buildCache(EhCacheProvider.java:84) 
at net.sf.hibernate.cache.StandardQueryCache.<init>(StandardQueryCache.java:42) 
at net.sf.hibernate.cache.StandardQueryCacheFactory.getQueryCache(StandardQueryCacheFactory.java:19) 
at net.sf.hibernate.impl.SessionFactoryImpl.getQueryCache(SessionFactoryImpl.java:637) 
at net.sf.hibernate.loader.Loader.list(Loader.java:1011) 
at net.sf.hibernate.hql.QueryTranslator.list(QueryTranslator.java:854) 
at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:1544) 
at net.sf.hibernate.impl.QueryImpl.list(QueryImpl.java:39) 

Thank you,
Daniel

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drosenbaum

Post subject:

Posted: Fri Oct 29, 2004 3:17 pm

Regular

Joined: Tue Nov 11, 2003 7:35 pm
Posts: 63

One thing I would like to add is that I do not have an entry in my ehcache.xml for this cache and therefore the cache gets created as the query executes. If it was in the ehcache.xml file the cache would have already been created at startup of ehcache and the problem would not occur.

Nevertheless I still believe it is a bug in the case where the cache is not in the ehcache.xml file.

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felipe.o.gutierrez

Post subject: Re: multiple thread problem with EHCache

Posted: Thu Feb 26, 2015 10:14 am

Newbie

Joined: Thu Feb 26, 2015 10:09 am
Posts: 1

Hi, I have the same problem. I am using multi threads. My ehcache configuration is ok for one thread, but for multi threads my app has to hit again the database and it does not consult ehcache. What configuration I am missing?

Here is my ehcache.xml. Thanks!

Code:

<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:noNamespaceSchemaLocation="ehcache.xsd" updateCheck="true"
   monitoring="autodetect" dynamicConfig="true">

   <diskStore path="user.dir/ehcache" />

   <defaultCache maxEntriesLocalHeap="10000" eternal="false"
      timeToIdleSeconds="0" timeToLiveSeconds="1800" diskSpoolBufferSizeMB="80"
      maxEntriesLocalDisk="10000000" diskExpiryThreadIntervalSeconds="120"
      memoryStoreEvictionPolicy="LRU" statistics="true">
      <persistence strategy="localTempSwap" />
   </defaultCache>

   <cache name="blockiscsi" maxEntriesLocalHeap="10000" eternal="false"
      timeToIdleSeconds="5" timeToLiveSeconds="10">
      <persistence strategy="localTempSwap" />
   </cache>

   <cache name="org.hibernate.cache.internal.StandardQueryCache"
      maxEntriesLocalHeap="5" eternal="false" timeToLiveSeconds="120">
      <persistence strategy="localTempSwap" />
   </cache>

   <cache name="org.hibernate.cache.spi.UpdateTimestampsCache"
      maxEntriesLocalHeap="5000" eternal="true">
      <persistence strategy="localTempSwap" />
   </cache>
</ehcache>

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