Reconciliation Exhausts LDAP Connection Pool

Symptom

SystemOut.log:

[4/9/13 22:01:33:688 CEST] 0000003a Cache A DYNA1070I: Cache
instance "services/cache/ldap_lt_cache" is full and has reached the
maximum configured size of 20000 entries. Space on the JVM heap for new
entries will now be made by evicting existing cache entries using the
LRU algorithm. Please consider enabling the disk offload feature for the
cache instance to prevent the discard of cache entries from memory.
[4/9/13 22:29:49:169 CEST] 0000001a ThreadMonitor W WSVR0605W: Thread
"SIBJMSRAThreadPool : 6" (00000056) has been active for 718434
milliseconds and may be hung. There is/are 2 thread(s) in total in the
server that may be hung.
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java:167)
at com.sun.jndi.ldap.pool.Connections.get(Connections.java:137)
at com.sun.jndi.ldap.pool.Pool.getPooledConnection(Pool.java:129)

Javacore:

3XMTHREADINFO "SIBJMSRAThreadPool : 2"
J9VMThread:0x00000000320B2000, j9thread_t:0x0000010017B0A3A0,
java/lang/Thread:0x0000000041EDC828, state:CW, prio=5
3XMTHREADINFO1 (native thread ID:0x3CB00A1, native
priority:0x5, native policy:UNKNOWN)
3XMTHREADINFO3 Java callstack:
4XESTACKTRACE at java/lang/Object.wait(Native Method)
4XESTACKTRACE at
java/lang/Object.wait(Object.java:167(Compiled Code))
4XESTACKTRACE at
com/sun/jndi/ldap/pool/Connections.get(Connections.java:137(Compiled
Code))
4XESTACKTRACE at
com/sun/jndi/ldap/pool/Pool.getPooledConnection(Pool.java:129(Compiled
Code))
4XESTACKTRACE at
com/sun/jndi/ldap/LdapPoolManager.getLdapClient(LdapPoolManager.java:310
(Compiled Code))
4XESTACKTRACE at
com/sun/jndi/ldap/LdapClient.getInstance(LdapClient.java:1572(Compiled
Code))