JDBC Driver under load

Has anyone used the JDBC driver under heavy load?

We're having a problem on one of our production machines that on some
occasions under heavy load Postgres JDBC connections seem to be dying /
locking up. Here's an example trace:

An I/O error occured while reading from backend - Exception:
java.net.SocketException: Connection reset by peer: Connection reset by peer
Stack Trace:
java.net.SocketException: Connection reset by peer: Connection reset by peer
        at java.net.SocketInputStream.socketRead(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:86)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java:186)
        at java.io.BufferedInputStream.read(BufferedInputStream.java:204)
        at org.postgresql.PG_Stream.ReceiveChar(PG_Stream.java:181)
        at org.postgresql.Connection.openConnection(Connection.java:160)
        at org.postgresql.Driver.connect(Driver.java:122)

or

An I/O error occured while reading from backend - Exception:
java.net.SocketException: Broken pipe: Broken pipe
Stack Trace:
java.net.SocketException: Broken pipe: Broken pipe
        at java.net.SocketInputStream.socketRead(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:86)
        at java.io.BufferedInputStream.fill(BufferedInputStream.java:186)
        at java.io.BufferedInputStream.read(BufferedInputStream.java:204)
        at org.postgresql.PG_Stream.ReceiveChar(PG_Stream.java:181)
        at org.postgresql.Connection.openConnection(Connection.java:160)
        at org.postgresql.Driver.connect(Driver.java:122)
...
        at org.postgresql.PG_Stream.ReceiveChar(PG_Stream.java:184)
        at org.postgresql.Connection.openConnection(Connection.java:160)
        at org.postgresql.Driver.connect(Driver.java:122)

any ideas where to start looking?

-mike