As Hotspot Express testing effort, I saw there are a lot of failures due to hanging in a particular app across Linux and Solaris platforms. The time it took varies from minutes to a couple of hours.
But after I attached Jconsole to the hanging processes, the app resumed running for a short while and then hanged again.

Note the failures do not happen to the regular product VM, but only to the VM that will be used in HS Express below.

Java Version:
Java(TM) SE Runtime Environment (build 1.6.0_02-b05)
Java HotSpot(TM) Tiered VM (build 20070615124853.et151817.baseline, mixed mode)

Flags: 1) "-server -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+ShowMessageBoxOnError -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+DisableExplicitGC -Xmx256m",
2) "-d64 -XX:+UseSerialGC -XX:+ShowMessageBoxOnError -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+DisableExplicitGC"

Host #1: jtg-t2000-5.sfbay (got interrupted with Jconsole)
Please contact the submitter for the logins.

log/core dump directory:
/bt/VolanoTestrun.27295.-server

Host #2: jtg-x4100-03.sfbay

log/core dump directory:
/bt/VolanoTestrun.2995.-d64