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

[Aleksey Shipilev]

On Tue, 7 Jan 2025 18:08:33 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> 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.

On my M1, the test now configures to much more reasonable heap size.


# Before
0s: Using 7 workers, each allocating: ~936M

# After
0s: Using 10 workers, each allocating: ~81M

-------------

PR Comment: https://git.openjdk.org/jdk/pull/22954#issuecomment-2575932718