Hello Mradoune,
I got something similar, in that case we were running with Tomcat, I guess you can try to customize:
-TraceOneMethodOfClass: org.apache.catalina.session.StandardSession expire
(Z) V SimpleDecrementor "Tomcat: Number of sessions"
TraceOneMethodOfClass: org.apache.catalina.session.StandardSession
SimpleIncrementor "Tomcat: Number of sessions"
Gustavo.