Hi, After 1 or 2 days of normal execution, the server hangs: I can't login by ssh or access to the web console (or any other application running on JBoss). The log of JBoss just stop without any exception. This problem started when I configured the pool size of may MDB with the @Pool annotation. I have more than 50 MDBs. Because of my performance problems (of throuput) I try to configure differents pool size on each MDBs. So, I'd configured \server\default\deploy\jca-jboss-beans.xml, with 2048. And put diferents values on each MDB. @ActivationConfigProperty(propertyName = "maxMessages", propertyValue = "1"), @ActivationConfigProperty(propertyName = "maxSession", propertyValue = "50")}) @Pool (value=PoolDefaults.POOL_IMPLEMENTATION_STRICTMAX,maxSize=50,timeout=20000) The sum of the all maxSize is around 1000. I've no problem of database connection. I've no OutOfMemory exception. I've no exception on my logs. My server is running on a VirtualBox 4, with 8 processors (the host has 16) with 6GB of RAM (the host has 16GB). I guess about a multithreading problem or a pool administration bug, but I can't found any solution. Can anybody help me? Thanks in advance. Martín PD: Server information: Version: 5.1.0.GA (build: SVNTag=JBoss_5_1_0_GA date=200905221100) Version Name: The Oracle Built on: May 22 2009 JVM Environment Free Memory: 2067 MB Max Memory: 2995 MB Total Memory: 2995 MB #Threads: 2206 JVM Version: 1.5.0_22-b03 (Sun Microsystems Inc.) JVM Name: Java HotSpot(TM) 64-Bit Server VM #CPU: 8 OS: Linux 2.6.32.39 (amd64)