My Oracle Support Banner

Java Application Hangs with Java Monitor Blocked at (Doc ID 2511764.1)

Last updated on NOVEMBER 14, 2020

Applies to:

Java SE JDK and JRE - Version 7 and later
Information in this document applies to any platform.


Java applications hang for 5-30 minutes with Java Monitor Blocked at and methods.

This particularly occurs with the Oracle Unified Directory application.  Examining the Java Flight Recorder, several threads show the following stack trace:

If the LDAP server listens on both ldap and ldaps protocol. The ldap port is never marked down, only the ldaps service port reports as down.

On the host, the below command does not return when the Load Balancer shows the ldaps service status is down:
ldapsearch -H ldaps://localhost:<PORT> -b dc=<COMPANY>,dc=<com> -D 'uid=<USERID> dc=<COMPANY>,dc=<com>' -w <PASSWORD> '(uid=<USERID>)'

The openssl commands hang as well.
# openssl s_client -connect localhost:<PORT> -showcerts connect <HOST>:<PORT>


To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

In this Document

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.