intermittent jps_info_validation_combination_14 timeout

The following test failure was spotted in the 2014-04-17 RT_Baseline nightly:

tmtools/jps/format-jar-absolute/jps_info_validation_combination_14

    This test failed due to "java.io.IOException: Stream closed" when
    server side was trying to send "Posting command: class
    tmtools.share.distributed.protocol.request.ShutDownRequest" to the
    client side. The client side failure mode is a timeout.

    The client side log shows:

[2014-04-18T09:44:34.91] * Got command: class tmtools.share.distributed.protocol.request.ShutDownRequest
[2014-04-18T09:44:34.92] Shutting down client
[2014-04-18T10:14:38.57] * Command class tmtools.share.distributed.protocol.request.ShutDownRequest executed successfully
[2014-04-18T10:14:38.58]

    so why did it take 30 minutes from printing "Shutting down client"
    to printing "... ShutDownRequest executed successfully"?