RFR(S): 8132723, 8132724: Add tests which check that soft/weak references to humongous objects should work correctly

[Jon Masamitsu]

Kirill,

Test looks good.

One enhancement you might consider (not necessarily for this
integration) is to print out "adr" and the g1 region for "adr" if the
test fails.  I'm guessing you can get the g1 region from WB.  If the 
test fails
and you have the list of g1 regions (it would be in the hs_err log file),
the first thing you might want to do is look up the g1 region to
see if there is anything unexpected about it.  Just something to
consider.

Jon


On 11/24/2015 11:05 AM, Kirill Zhaldybin wrote:
> Hi!
>
> Could you please review the following patch that adds a test that 
> checks that soft/weak references to humongous objects work correctly?
>
> The test checks that weak and soft references behave correspondingly
> to actual object behavior:
> 1. If an object is collected a weak/soft reference .get() should
> return null.
> 2. If an object is not collected a weak/soft reference .get() should
> not return null.
>
> Two White Box API methods were added:
> 1. g1BelongsToHumongousRegion which checks that address belongs to
> humongous region
> 2. g1BelongsToFreeRegion which checks that address belongs to free region
> These methods do not  impact G1 performance/stability since they don't 
> change anything in G1 execution.
>
> The only used method from gc/testlibrary is waitTillCMCFinished, which 
> is under review here -
> http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2015-November/015643.html 
>
>
> CR: https://bugs.openjdk.java.net/browse/JDK-8132723
>     https://bugs.openjdk.java.net/browse/JDK-8132724
>
> Webrev:
>     main: 
> http://cr.openjdk.java.net/~kzhaldyb/webrevs/JDK-8132724/webrev.02/main/
>     hotspot: 
> http://cr.openjdk.java.net/~kzhaldyb/webrevs/JDK-8132724/webrev.02/hotspot/
>
> Thank you.
>
> Regards, Kirill