Hi,
     I have been performance tuning jboss, and have came across an issue 
related to DataSources.   Each time I run a 500 user test, the application 
"pauses" for 200 seconds or so(no responses are seen).   I have tracked this 
down to two separate issues, the first was with the number of Open file 
descriptors.  I am using RHEL3, and this is set to 1024, for an indiviual 
process.  I have moved this to 2048, on the grounds that each user 
connection(we are connecting directly to jboss), consumes one connection, and 
logically since everything in linux is a file, needs one file descriptor.  I no 
longer get the "Too many open files"(note I have checked for increasing numbers 
of open files, but do not see this increasing over time), effectively I have an 
application that requires a lot of open file descriptors.  Now this is 
stabalised. 

    However, I still get the problem with "No managed connections available".   
I have changed all the relevant DataSource maximum connections from a default 
of 20, to a new default maximum of 200(changed in the ds.xml for each 
datasource).   I have monitored the application and am getting around 100 data 
source connections maximum, per data source(ie I should have another 100 
"spare").  

    However, I still have the error that there are no managed connections 
available.   

    Can anyone shed any light on what options I might try next to track this 
down?

      I have included a stack trace from the log file.....




Caused by: org.jboss.util.NestedSQLException: No ManagedConnections available 
within configured blocking timeout ( 30000 [ms] ); - neste
d throwable: (javax.resource.ResourceException: No ManagedConnections available 
within configured blocking timeout ( 30000 [ms] ))
        at 
org.jboss.resource.adapter.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:94)
        at 
org.jboss.ejb.txtimer.GeneralPurposeDatabasePersistencePlugin.insertTimer(GeneralPurposeDatabasePersistencePlugin.java:172)
        at 
org.jboss.ejb.txtimer.DatabasePersistencePolicy.insertTimer(DatabasePersistencePolicy.java:122)
        ... 100 more
Caused by: javax.resource.ResourceException: No ManagedConnections available 
within configured blocking timeout ( 30000 [ms] )
        at 
org.jboss.resource.connectionmanager.InternalManagedConnectionPool.getConnection(InternalManagedConnectionPool.java:266)
        at 
org.jboss.resource.connectionmanager.JBossManagedConnectionPool$BasePool.getConnection(JBossManagedConnectionPool.java:454)
        at 
org.jboss.resource.connectionmanager.BaseConnectionManager2.getManagedConnection(BaseConnectionManager2.java:324)
        at 
org.jboss.resource.connectionmanager.TxConnectionManager.getManagedConnection(TxConnectionManager.java:301)
        at 
org.jboss.resource.connectionmanager.BaseConnectionManager2.allocateConnection(BaseConnectionManager2.java:379)
        at 
org.jboss.resource.connectionmanager.BaseConnectionManager2$ConnectionManagerProxy.allocateConnection(BaseConnectionManager2.
java:812)
        at 
org.jboss.resource.adapter.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:88)
        ... 102 more




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