RFR: 8347126: gc/stress/TestStressG1Uncommit.java gets OOM-killed

[Aleksey Shipilev]

One of my testing nodes caught the OOM kill for the VM carrying the test. The default configuration turns the VM that test runs as the driver into a memory hog. On 48-core / 64G machine, the test configured itself to take 13 workers each allocating 1G. This ballooned the heap size to 13G -- e.g. about 25% of host memory  -- which is well beyond the usual footprint for a single test VM (~2GB). Naturally, this runs into a high chance of being OOM killed under high test parallelism.

The solution is cut down the heap size we run with, and balance the number of workers a bit more finely. I looked around at sibling tests and 1G seems to be a common heap size for these tests.

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/22954/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22954&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347126
  Stats: 4 lines in 1 file changed: 1 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/22954.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22954/head:pull/22954

PR: https://git.openjdk.org/jdk/pull/22954