Current default number of test jobs is derived from the number of hardware threads available. When there is 2 GB or less memory available per hardware thread, many tests start to run out of memory.

JDK-8212028 did, among other things, the consistent calculation of test jobs. It basically moved the calculation of test jobs that is done for Hotspot jtregs to the global configuration for all test jobs. This allows langtools tests to run on large machines without problems.

Backporting the entire JDK-8212028 is risky, so pulling out the TEST_JOBS related change is in order.

The alternative/workaround is to override TEST_JOBS manually for each machine.