[hibernate-issues] [Hibernate-JIRA] Updated: (HHH-4068) Hibernate's ReadWriteCache synchronization slow down ehcache

[Dror Bereznitsky (JIRA)]

     [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-4068?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dror Bereznitsky updated HHH-4068:
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    Attachment: screenshot-1.jpg

Threads waiting for the ReadWriteCache monitor

> Hibernate's ReadWriteCache synchronization slow down ehcache 
> -------------------------------------------------------------
>
>                 Key: HHH-4068
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4068
>             Project: Hibernate Core
>          Issue Type: Bug
>            Reporter: shaoxian yang
>         Attachments: screenshot-1.jpg
>
>
> Hi, I am setting up hibernate to work with ehcache. Hibernate has a wrapper to call underlying ehcache.  
>  
> Their wrappers are ReadWriteCache.java, which internally will call Ehcache. The two major methods in ReadWriteCache are synchronized: 
>  
> public synchronized Object get(Object key, long txTimestamp) throws CacheException { 
> public synchronized boolean put( 
> Object key,  
> Object value,  
> long txTimestamp,  
> Object version,  
> Comparator versionComparator, 
> boolean minimalPut)  
>  
>  
> I understand this is to ensure "read/write" strategy to read committed (when write and read thread get in at the same time, read does not get intermediate result and only get the latest committed result).  
>  
> However, isn't this also make concurrent read impossible when there is no write? ).  
>  
> It looks like we need some more advanced read/write lock at ReadWriteCache level. However, the class also have other synchronized methods which make me hesitate: 
>  
> public synchronized SoftLock lock(Object key, Object version) throws CacheException 
> public synchronized void release(Object key, SoftLock clientLock) throws CacheException  
> public synchronized boolean afterUpdate(Object key, Object value, Object version, SoftLock clientLock)  
> throws CacheException 
> public synchronized boolean afterInsert(Object key, Object value, Object version)  
> throws CacheException 
> public synchronized SoftLock lock(Object key, Object version) throws CacheException  
>  
>    
>  
> Basically I want to get the most out of ehcache performance gain. Currently, if I keep issuing the same query which read item from query cache, there is still overhead.
> Can you advise me why we have to use read lock for every read when there is no write?  And is it necessary to acquire lock for any other operation than put/get in ReadWriteCache class?
> Thanks in advance.

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