The problem occurs when both a client application with Access Manager clientsdk.jar and Access Manager server are in the Access Manager JVM instance. When an JavaEE application tries to access IdRepo attributes for any identity, then Access Manager server can hang. The problem is due to the unnecessary synchronization block in SMS ServiceConfigImpl, OrganizationConfigManagerImpl and ServiceConfigManagerImpl in Access Manager SDK. This known issue was address in Access Manager 7.1.
Solution: Upgrade to Access Manager 7.1