thread hang on execute call

Hi
i have some worker threads that perform some database intensive
operation after each fixed interval.so they keeps running.
after 2 days all threads got hang on execute call on jdbc driver.
there are around 60000 rows in table.
i get no response and following is

here is stack trace of postgres process

#0 0x003437a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
#1 0x00424451 in recv () from /lib/tls/libc.so.6
#2 0x08145aae in secure_read ()
#3 0x0814c062 in pq_recvbuf ()
#4 0x0814c121 in pq_getbyte ()
#5 0x081ad5fc in PostgresMain ()
#6 0x0818765d in ServerLoop ()
#7 0x0818904f in PostmasterMain ()
#8 0x0814dd18 in main ()

and following is stack trace of java thread

Thread 12912: (state = IN_NATIVE)
- java.net.SocketInputStream.socketRead0(java.io.FileDescriptor,
byte[], int, int, int) @bci=0 (Compiled frame; information may be
imprecise)
- java.net.SocketInputStream.read(byte[], int, int) @bci=84, line=129
(Compiled frame)
- java.io.BufferedInputStream.fill() @bci=175, line=218 (Compiled
frame)
- java.io.BufferedInputStream.read() @bci=12, line=235 (Compiled frame)
- org.postgresql.core.PGStream.ReceiveChar() @bci=4, line=254 (Compiled
frame)
-
org.postgresql.core.v3.QueryExecutorImpl.execute(org.postgresql.core.Query, org.postgresql.core.ParameterList, org.postgresql.core.ResultHandler, int, int, int) @bci=129, line=188 (Interpreted frame)
-
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(org.postgresql.core.Query, org.postgresql.core.ParameterList, int) @bci=199, line=430 (Interpreted frame)
- org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(int)
@bci=14, line=346 (Compiled frame)
- org.postgresql.jdbc2.AbstractJdbc2Statement.execute() @bci=2,
line=339 (Interpreted frame)
- org.apache.commons.dbcp.DelegatingPreparedStatement.execute() @bci=8,
line=168 (Interpreted frame)

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