Vincent Massol wrote:
Hi JV,
Are you sure about this patch?
It looks like it's adding a synchronize() that was not there before and thus all threads will be waiting on this synchronize. Since checkHibernate is called for all database access I'm worried this could lead to performance issues.
This should not affect performance as the synchronize() will take place only during the first request, when hibernate is initialized.
Has this been tested for performance with a tool like JMeter to simulate multiple users?
Note that I haven't analyzed the patch. I'm just worried that we might be introducing a regression in term of performance.
If the session factory is only created once then maybe it should be created on app init?
+1. We need to initialize things on startup, and not on requests.
Thanks -Vincent
On Apr 10, 2008, at 6:21 PM, jvdrean (SVN) wrote:
Author: jvdrean Date: 2008-04-10 18:21:07 +0200 (Thu, 10 Apr 2008) New Revision: 9071
Modified: xwiki-platform/core/branches/xwiki-core-1.3/xwiki-core/src/main/ java/com/xpn/xwiki/store/XWikiHibernateBaseStore.java Log: XWIKI-2300 : HibernateStore synchronization problem
Applied patch by Raffaello Pelagalli without modification. Added comment.
Modified: xwiki-platform/core/branches/xwiki-core-1.3/xwiki-core/src/ main/java/com/xpn/xwiki/store/XWikiHibernateBaseStore.java =================================================================== --- xwiki-platform/core/branches/xwiki-core-1.3/xwiki-core/src/main/ java/com/xpn/xwiki/store/XWikiHibernateBaseStore.java 2008-04-10 14:45:54 UTC (rev 9070) +++ xwiki-platform/core/branches/xwiki-core-1.3/xwiki-core/src/main/ java/com/xpn/xwiki/store/XWikiHibernateBaseStore.java 2008-04-10 16:21:07 UTC (rev 9071) @@ -510,13 +510,18 @@ */ public void checkHibernate(XWikiContext context) throws HibernateException { - + // Note : double locking is not a recommended pattern and is not guaranteed to work on all + // machines. See for example http://www.ibm.com/developerworks/java/library/j-dcl.html if (getSessionFactory() == null) { - initHibernate(); - - /* Check Schema */ - if (getSessionFactory() != null) { - updateSchema(context); + synchronized(this) { + if (getSessionFactory() == null) { + + initHibernate(); + /* Check Schema */ + if (getSessionFactory() != null) { + updateSchema(context); + } + } } } }
-- Sergiu Dumitriu http://purl.org/net/sergiu/