Thread Dump showing thread who has locked DatabaseConnectionFactory:

"EventQueueProcessor" prio=5 tid=0x008262d0 nid=0x3b runnable [239ff000..239ffc28]
        at java.net.SocketInputStream.socketRead0(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:129)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java:183)
        at java.io.BufferedInputStream.read(BufferedInputStream.java:201)
        - locked <0x8183b8a8> (a java.io.BufferedInputStream)
        at org.postgresql.core.PGStream.ReceiveChar(PGStream.java:166)
        at org.postgresql.core.QueryExecutor.executeV3(QueryExecutor.java:127)
        - locked <0x8183b8c8> (a org.postgresql.core.PGStream)
        at org.postgresql.core.QueryExecutor.execute(QueryExecutor.java:100)
        at org.postgresql.core.QueryExecutor.execute(QueryExecutor.java:43)
        at org.postgresql.jdbc1.AbstractJdbc1Connection.execSQL(AbstractJdbc1Connection.java:887)
        at org.postgresql.jdbc1.AbstractJdbc1Connection.openConnectionV3(AbstractJdbc1Connection.java:505)
        at org.postgresql.jdbc1.AbstractJdbc1Connection.openConnection(AbstractJdbc1Connection.java:214)
        at org.postgresql.Driver.connect(Driver.java:139)
        at java.sql.DriverManager.getConnection(DriverManager.java:512)
        - locked <0xf1b8f260> (a java.lang.Class)
        at java.sql.DriverManager.getConnection(DriverManager.java:171)
        - locked <0xf1b8f260> (a java.lang.Class)
        at org.opennms.netmgt.config.DatabaseConnectionFactory.getConnection(DatabaseConnectionFactory.java:1120)
        - locked <0x328b2758> (a java.util.LinkedList)
        at org.opennms.netmgt.xmlrpcd.XmlRpcNotifier.getNodeLabel(XmlRpcNotifier.java:355)



pstack showing the FD of java->pgsql socket read call:

-----------------  lwp# 59 / thread# 59  --------------------
 ff33d2d8 read     (36, 939a18, 2000)
 feccbc30 JVM_Read (36, 939a18, 2000, feccb5c8, ff364278, ff36c950) + 68
 30edac88 Java_java_net_SocketInputStream_socketRead0 (826364, 239ff100, 239ff0fc, 239ff0f8, 0, 2000) + 1e8


pfiles showing port number of the java->psql socket read call:

  54: S_IFSOCK mode:0666 dev:304,0 ino:16062 uid:0 gid:0 size:0
      O_RDWR
        SOCK_STREAM
        SO_SNDBUF(49152),SO_RCVBUF(49152)
        sockname: AF_INET 127.0.0.1  port: 50912
        peername: AF_INET 127.0.0.1  port: 5432

...after greping through the pfiles output of 17 postmaster processes, found
the one that has socket 50912 open:

   8: S_IFSOCK mode:0666 dev:304,0 ino:13881 uid:0 gid:0 size:0
      O_RDWR
        SOCK_STREAM
        SO_REUSEADDR,SO_KEEPALIVE,SO_SNDBUF(49152),SO_RCVBUF(49152)
        sockname: AF_INET 127.0.0.1  port: 5432
        peername: AF_INET 127.0.0.1  port: 50912

pstack of this postmaster process:

3029:   /usr/local/pgsql/bin/postmaster -D /usr/local/pgsql/data
 fefbca1c recv     (8, 283df0, 2000, 0)
 000f7420 pq_getbyte (285c00, 328598, 1, 6, 5cbd8, 5cc30) + 38
 00156a38 SocketBackend (ffbff1d8, 49, 0, 49, 0, 2) + 4
 00156d28 ReadCommand (ffbff1d8, 0, ffffffff, fffffff8, 0, 2ad800) + 20
 00159c94 PostgresMain (4, 2c3850, 2c3830, 6, 0, 0) + a7c
 0012e414 BackendRun (2d2038, 1084, 916e0, 0, ff1d2000, 1000) + 5b8
 0012dc60 BackendStartup (2d2038, 2b3b0c, 0, 0, 2b3800, 5) + 150
 0012bfdc ServerLoop (2, 2b3800, 2b3800, ffbffb98, ffbffc38, 286000) + 304
 0012b7c8 PostmasterMain (0, 2bffe8, 2c7aa0, 2bf000, 2be400, 23f000) + b10
 000f89cc main     (3, 2bffe8, ffbffe2c, 2be6dc, ff1d0140, ff1d0180) + 220
 00039d44 _start   (0, 0, 0, 0, 0, 0) + 5c


Conclusion java is doing a read on this socket, and postmaster is doing a recv.