java program works fine in RHEL 5, hangs in RHEL 6

Issue

The hang can occur randomly at different locations in the Java code but always ends up hung in SocketInputStream.available waiting on a network call to complete:

        at java.net.PlainSocketImpl.socketAvailable(Native Method)
        at java.net.PlainSocketImpl.available(PlainSocketImpl.java:454)
        - locked <0x00007f2bb1046580> (a java.net.SocksSocketImpl)
        at java.net.SocketInputStream.available(SocketInputStream.java:217)
        at java.io.BufferedInputStream.available(BufferedInputStream.java:381)
        - locked <0x00007f2bb1014000> (a java.io.BufferedInputStream)
        at electric.http.InboundHTTPResponse.close(InboundHTTPResponse.java:188)