OSB strange blocked threads while hammering a server

I was pounding with requests a service with TRACING and LOGGING enabled, at debug level. This seemps to create a lot of contention. Avoid using tracing in any critical environment (prod).

"[ACTIVE] ExecuteThread: '82' for queue: 'weblogic.kernel.Default (self-tuning)'" daemon prio=10 tid=0x00002aaacc3cc000 nid=0x1086 waiting for monitor entry [0x000000004b404000]
   java.lang.Thread.State: BLOCKED (on object monitor)
 at org.apache.xmlbeans.impl.store.Path.getCompiledPath(Path.java:136)
 - waiting to lock <0x0000000767e381f0> (a java.lang.Class for org.apache.xmlbeans.impl.store.Path)
 at org.apache.xmlbeans.impl.store.Path.getCompiledPath(Path.java:130)
 at org.apache.xmlbeans.impl.store.Cursor._selectPath(Cursor.java:902)
 at org.apache.xmlbeans.impl.store.Cursor.selectPath(Cursor.java:2634)
 - locked <0x00000007f8276f38> (a org.apache.xmlbeans.impl.store.Locale)



"[ACTIVE] ExecuteThread: '61' for queue: 'weblogic.kernel.Default (self-tuning)'" daemon prio=10 tid=0x00002aaaba01d800 nid=0xa59 waiting for monitor entry [0x0000000049ff0000]
   java.lang.Thread.State: BLOCKED (on object monitor)
 at com.bea.logging.RotatingFileStreamHandler.publish(RotatingFileStreamHandler.java:75)
 - waiting to lock <0x0000000797c61b08> (a weblogic.logging.FileStreamHandler)
 at java.util.logging.Logger.log(Logger.java:478)
 at com.bea.logging.BaseLogger.log(BaseLogger.java:51)
 at weblogic.logging.WLLogger.log(WLLogger.java:40)
 at com.bea.logging.LoggingService.log(LoggingService.java:250)
 at com.bea.wli.sb.messages.ServiceLogger.enterPipelinePair(ServiceLogger.java:1693)
 at com.bea.wli.sb.pipeline.LoggingTracingStep.traceEnter(LoggingTracingStep.java:211)

to be investigated.... If you find the same issue, please scream.