RFR: 8234382: Test tools/javac/processing/model/testgetallmembers/Main.java using too small heap

[Per Liden]

Hi,

Please review this one-liner test fix.

The test tools/javac/processing/model/testgetallmembers/Main.java is 
assuming that a 256M heap is enough to hold its live-set, but this is 
only true under some conditions. There are a number of JVM flags that, 
when used, can break this assumption. For example, choice of GC, 
compressed oop, object alignment, and other options affecting the heap 
layout or allocation strategy. Under ideal conditions, the test is 
already fairly close to using the whole heap, so it doesn't take that 
much to push it over the edge. For example, the following combinations 
all fail:

-XX:+UseSerialGC -XX:-UseCompressedOops
-XX:+UseParallelGC -XX:-UseCompressedOops
-XX:+UseZGC (always has -XX:-UseCompressedOops)
-XX:+UseG1GC -XX:-UseCompressedOops -XX:ObjectAlignmentInBytes=16

I suggest we bump the max heap size to something like 512M, to give the 
test more headroom and make it less sensitive to exact choice of JVM flags.

Bug: https://bugs.openjdk.java.net/browse/JDK-8234382
Webrev: http://cr.openjdk.java.net/~pliden/8234382/webrev.0

/Per