code review request: 7092627: use agentvm mode instead of samevm in regtests

[Weijun Wang]

Here is the webrev:

    http://cr.openjdk.java.net/~weijun/7092627/webrev.00/

The major reason for this change is that in samevm mode, sometimes a 
test leaves garbage here or there and jtreg cannot do a successfull 
cleanup and every test following it in the same testsuite fails. By 
using agentvm, jtreg can create a new VM for these tests and let the 
test go on.

We do notice some issues in switching from samevm to agentvm. One of 
them is com/sun/jdi/sde/MangleStepTest.java, which fails on all 
platforms once agentvm is turned on. 
java/util/logging/ParentLoggersTest.java fails on all solaris 64 bit 
platforms (solaris-x64 and solaris-sparcv9) . They are moved to othervm 
mode and bugs are created to track the problem. There are other formerly 
unstable tests that become more unstable, and anyway they need to be fixed.

The agentvm mode accepts a concurrency option that allows multiple 
testing VMs running at the same time. The current value is set to 1. 
Since JPRT already runs multiple tests on the same client, it's probably 
not a good idea to run even more. The major purpose of this code change 
is to enhance stability but not performance.

Also, setting the concurrency number higher seems to make agentvm mode 
unstable. In our experiments, 80% of the tests see a 20% time saving 
when the number is changed from 1 to 2. But the other 20% consumes much 
more time, some hang for ever.

Thanks
Max


-------- Original Message --------
*Change Request ID*: 7092627
*Synopsis*: use agentvm mode instead of samevm in regtests

   Product: java
   Category: java
   Subcategory: test

=== *Description* 
============================================================
agentvm mode is an enhanced samevm mode that allows automatic new VM 
creation when there is any unrecoverable error during test execution. It 
also allows tests running in multiple VMs simultaneously.