[jbossseam-issues] [JBoss JIRA] Created: (JBSEAM-3519) Excessive JNDI lookups for "java:comp/UserTransation"

[Jay Balunas (JIRA)]

Excessive JNDI lookups for "java:comp/UserTransation"
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                 Key: JBSEAM-3519
                 URL: https://jira.jboss.org/jira/browse/JBSEAM-3519
             Project: Seam
          Issue Type: Bug
          Components: Core, Performance and Scalability
    Affects Versions: 2.1.0.CR1
            Reporter: Jay Balunas
            Assignee: Shane Bryzak
            Priority: Critical
             Fix For: 2.1.1.CR1


NOTE: There are more details to this on the seam-dev email list and its archives.  Below is the primary email that broke down the behavior.

A single user making a single request to the Seam wiki example's user forum front page performs 114 JNDI lookups for "java:comp/UserTransation".  This means that not only are 144 instances of IntialContext created, but we have 114 actual lookups as well.  This is nearly linear with 2 requests creating 228 JNDI lookups + some for ajax4jsf caching calls as described below.  Extrapolating to the 25 user test that would be 25x114=2850 jndi lookups for each round of requests. 

At least for the wiki page I am testing there were no other JNDI lookups.

Who is looking up "java:comp/UserTransation"
--------------------------------------------------------
All of these calls can be traced to Transaction.instance().  I broke down all of the calls to Transaction.instance() during a single request to the user forum page on the wiki.  

81 - seam.util.Work.workInTransaction(Work.java:34) via (TransactionInterceptor.java:34)
  1 - SeamPhaseListener.handleTransactionsBeforePhase(SeamPhaseListener.java:319)
  3 - SeamPhaseListener.begin(SeamPhaseListener.java:591)                          
  3 - SeamPhaseListener.begin(SeamPhaseListener.java:594)                          
  3 - SeamPhaseListener.commitOrRollback(SeamPhaseListener.java:611)       
  3 - SeamPhaseListener.commitOrRollback(SeamPhaseListener.java:614)       
  8 - ManagedPersistenceContext.joinTransaction(ManagedPersistenceContext.java:120)
  6 - Contexts.flushAndDestroyContexts(Contexts.java:331)                          
  6 - ManagedPersistenceContext.close(ManagedPersistenceContext.java:192)        
-------------
114 - Total

I then broke it down by which JSF lifecycle phase it was done in.

Phase Breakdown:
------------------
3   - During RESTORE_VIEW                    
2   - Between RESTORE_VIEW and RENDER_RESPONSE
91 - During RENDER_RESPONSE                  
18 - After RENDER_RESPONSE                  
----------
114 total

I then did the same break down on a second follow up request with the same session

Second Request showed a different distribution:
------------------------------------------------
3   - During RESTORE_VIEW                          
2   - Between RESTORE_VIEW and RENDER_RESPONSE     
91 - During RENDER_RESPONSE                      
5   - After RENDER_RESPONSE                        
3   - During 2nd RESTORE_VIEW                      
0   - Between 2nd RESTORE_VIEW and RENDER_RESPONSE 
1   - During 2nd RENDER_RESPONSE                   
3   - After 2nd RENDER_RESPONSE                    
3   - During 3rd RESTORE_VIEW                      
0   - Between 3rd RESTORE_VIEW and RENDER_RESPONSE 
1   - During 3rd RENDER_RESPONSE                   
16 - After 3rd RENDER_RESPONSE                   
------------          
128 total

The extra 14 lookups are all during the extra 2 mini requests.  They all pass through this ajax4jsf class "org.ajax4jsf.resource.ResourceLifecycle.invokePhaseListener(ResourceLifecycle.java:[199/201])".  I'm assuming that these extra calls are related to page fragment caching and/or resources that are provided through the ajax4jsf InternetResourceService.  Christian can you confirm?

Conclusions:
---------------------
We obviously need to find more ways to improve this behavior.  The primary offender is "Work.java" (see: http://fisheye.jboss.org/browse/Seam/trunk/src/main/org/jboss/seam/util/Work.java?r=8624#l34 ).  This single line is checking if the transaction is currently active.  81 time it is active and processing continues as normal.  Is there a way we can cache this value for the length of the request (either the transaction, or the result)?  Caching the result could be bad if something changed during the request, so we would need the actual transaction.

Also many of the lookups were the result of EL processing during the RENDER_RESPONSE phase.  Ideally these would primarily be read-only requests or close to it.  Could there be a way to disable the transactional calls for items somehow tagged read only?  I have not give that much thought yet so it might need some flushing out ;-)

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