RFR (L): 8024319: Add regression tests on documented GC-related -XX:+Print* options

[denis kononenko]

Hi All,

Could you please review new tests on GC-related -XX:Print options.

Webrev link: 
http://cr.openjdk.java.net/~eistepan/dkononen/8024319/webrev.00/
Bug id: https://bugs.openjdk.java.net/browse/JDK-8024319
Testing: automated
Description:

There is a group of new tests to test the following GC options:

-XX:+-PrintAdaptiveSizePolicy
-XX:+-PrintGCApplicationConcurrentTime
-XX:+-PrintGCApplicationStoppedTime
-XX:+-PrintGCDateStamps
-XX:+-PrintGCDetails
-XX:+-PrintGC
-XX:+-PrintGCTimeStamps
-XX:+-PrintTenuringDistribution

Each of the tested options has a pair of corresponding tests, one is for 
testing an enabled option and another for disabled. The tests are simple 
parsers of GC's logger output and looking for a specific marker 
corresponding to the tested option. The output is provided by another 
process which is implemented in GCTask.java. It's necessary because we 
have to guarantee that GC's log has been completely written and 
committed to the filesystem before we start analyzing it. The most 
obvious solution is to politely finish the writing process. Thus the 
every test spawns an auxiliary process  which produces GC's log file, 
waits for its finish, loads the output and then performs actual testing. 
These steps are implemented with jtreg's annotations and a helper class 
which can be found AbstractPrintGCTest.java. This class encapsulates 
reading GC's log output from the log file and provides that output to 
the tests.

To get GC's logger working GCTask forces the garbage collecting process. 
It attempts to consume all memory available to the young generation by 
creating a lot of unreferenced objects. Sooner or later the garbage 
collector shall be invoked. In favor of performance the task is 
implemented to be ran with a small memory size less or equal to 128 
megabytes. This is excplicitly specified with -Xmx JVM's option in 
jtreg's annotations.

Please note that some options work for specific GCs only. To prevent 
them from being executed against wrong GC jtreg's annotations and groups 
are used.

Thank you,
Denis.