Race condition in building query cache -------------------------------------- Key: HHH-5945 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5945 Project: Hibernate Core Issue Type: Bug Components: caching (L2) Affects Versions: 3.6.1 Environment: Hibernate 3.6.1, EhCache 2.3.0..2.3.2, MSSQL 2005 Developer Edition Reporter: Luca Domenichini Attachments: TestCase.zip Original Estimate: 1h Remaining Estimate: 1h I have this sample program that creates 10 threads that executes the same cached query in a thread-local current session context. Entity ClasseAltezza is a READ_ONLY cached entity. {panel}{noformat} public static void main(String[] args) { List<Thread> threads = new ArrayList<Thread>(); for (int i=0; i<10; i++) { Thread t = new Thread() { @Override public void run() { try { HibernateUtil.beginTransaction(); HibernateUtil.getCurrentSession() .createCriteria(ClasseAltezza.class) .setCacheable(true) .setCacheRegion(ClasseAltezza.class.toString()) .list(); HibernateUtil.commitTransaction(); } catch (Exception ex) { ex.printStackTrace(); HibernateUtil.rollbackTransaction(); } } }; threads.add(t); } for (Thread t : threads) t.start(); } {noformat}{panel} This is the output: {panel}{noformat}org.hibernate.cache.CacheException: net.sf.ehcache.ObjectExistsException: Cache class com.promag.wms.base.persistence.entities.ClasseAltezza already exists at org.hibernate.cache.EhCacheProvider.buildCache(EhCacheProvider.java:101) at org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge.buildQueryResultsRegion(RegionFactoryCacheProviderBridge.java:115) at org.hibernate.cache.StandardQueryCache.<init>(StandardQueryCache.java:78) at org.hibernate.cache.StandardQueryCacheFactory.getQueryCache(StandardQueryCacheFactory.java:44) at org.hibernate.impl.SessionFactoryImpl.getQueryCache(SessionFactoryImpl.java:1173) at org.hibernate.loader.Loader.listUsingQueryCache(Loader.java:2285) at org.hibernate.loader.Loader.list(Loader.java:2268) at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:119) at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1716) at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:347) at com.promag.wms.base.persistence.methods.ClasseAltezzaMethods.getAll(ClasseAltezzaMethods.java:30) at Test$1.run(Test.java:20) Caused by: net.sf.ehcache.ObjectExistsException: Cache class com.promag.wms.base.persistence.entities.ClasseAltezza already exists at net.sf.ehcache.CacheManager.addCache(CacheManager.java:888) at org.hibernate.cache.EhCacheProvider.buildCache(EhCacheProvider.java:94) ... 11 more {noformat}{panel} I see that in Hibernate 3.6.0 there were a synchronized block in method SessionFactory.getQueryCache(String regionName) the prevented the same query region to be built twice as it happens in Hibernate 3.6.1, were the synchronized block is missing.. This is the method in SessionFactoryImpl: {panel}{noformat} public QueryCache getQueryCache(String regionName) throws HibernateException { if ( regionName == null ) { return getQueryCache(); } if ( !settings.isQueryCacheEnabled() ) { return null; } synchronized ( allCacheRegions ) { // THIS SYNCHRONIZED IS MISSING IN 3.6.1!!!! QueryCache currentQueryCache = ( QueryCache ) queryCaches.get( regionName ); if ( currentQueryCache == null ) { currentQueryCache = settings.getQueryCacheFactory().getQueryCache( regionName, updateTimestampsCache, settings, properties ); queryCaches.put( regionName, currentQueryCache ); allCacheRegions.put( currentQueryCache.getRegion().getName(), currentQueryCache.getRegion() ); } return currentQueryCache; } } {noformat}{panel}

Race condition in building query cache -------------------------------------- Key: HHH-5945 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5945 Project: Hibernate Core Issue Type: Bug Components: caching (L2) Affects Versions: 3.6.1 Environment: Hibernate 3.6.1, EhCache 2.3.0..2.3.2, MSSQL 2005 Developer Edition Reporter: Luca Domenichini Assignee: Strong Liu Fix For: 4.0.0.next Attachments: TestCase.zip Original Estimate: 1h Remaining Estimate: 1h I have this sample program that creates 10 threads that executes the same cached query in a thread-local current session context. Entity ClasseAltezza is a READ_ONLY cached entity. {panel}{noformat} public static void main(String[] args) { List<Thread> threads = new ArrayList<Thread>(); for (int i=0; i<10; i++) { Thread t = new Thread() { @Override public void run() { try { HibernateUtil.beginTransaction(); HibernateUtil.getCurrentSession() .createCriteria(ClasseAltezza.class) .setCacheable(true) .setCacheRegion(ClasseAltezza.class.toString()) .list(); HibernateUtil.commitTransaction(); } catch (Exception ex) { ex.printStackTrace(); HibernateUtil.rollbackTransaction(); } } }; threads.add(t); } for (Thread t : threads) t.start(); } {noformat}{panel} This is the output: {panel}{noformat}org.hibernate.cache.CacheException: net.sf.ehcache.ObjectExistsException: Cache class com.promag.wms.base.persistence.entities.ClasseAltezza already exists at org.hibernate.cache.EhCacheProvider.buildCache(EhCacheProvider.java:101) at org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge.buildQueryResultsRegion(RegionFactoryCacheProviderBridge.java:115) at org.hibernate.cache.StandardQueryCache.<init>(StandardQueryCache.java:78) at org.hibernate.cache.StandardQueryCacheFactory.getQueryCache(StandardQueryCacheFactory.java:44) at org.hibernate.impl.SessionFactoryImpl.getQueryCache(SessionFactoryImpl.java:1173) at org.hibernate.loader.Loader.listUsingQueryCache(Loader.java:2285) at org.hibernate.loader.Loader.list(Loader.java:2268) at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:119) at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1716) at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:347) at com.promag.wms.base.persistence.methods.ClasseAltezzaMethods.getAll(ClasseAltezzaMethods.java:30) at Test$1.run(Test.java:20) Caused by: net.sf.ehcache.ObjectExistsException: Cache class com.promag.wms.base.persistence.entities.ClasseAltezza already exists at net.sf.ehcache.CacheManager.addCache(CacheManager.java:888) at org.hibernate.cache.EhCacheProvider.buildCache(EhCacheProvider.java:94) ... 11 more {noformat}{panel} I see that in Hibernate 3.6.0 there were a synchronized block in method SessionFactory.getQueryCache(String regionName) the prevented the same query region to be built twice as it happens in Hibernate 3.6.1, were the synchronized block is missing.. This is the method in SessionFactoryImpl: {panel}{noformat} public QueryCache getQueryCache(String regionName) throws HibernateException { if ( regionName == null ) { return getQueryCache(); } if ( !settings.isQueryCacheEnabled() ) { return null; } synchronized ( allCacheRegions ) { // THIS SYNCHRONIZED IS MISSING IN 3.6.1!!!! QueryCache currentQueryCache = ( QueryCache ) queryCaches.get( regionName ); if ( currentQueryCache == null ) { currentQueryCache = settings.getQueryCacheFactory().getQueryCache( regionName, updateTimestampsCache, settings, properties ); queryCaches.put( regionName, currentQueryCache ); allCacheRegions.put( currentQueryCache.getRegion().getName(), currentQueryCache.getRegion() ); } return currentQueryCache; } } {noformat}{panel}