Two cases we have seen the commit queue running out memory. The unittest source files are rather memory intensive, in the 4-5 GB range. With a j36 build, its entirely possible to OOM from compiles.

slack thread 1
task 1

slack thread 2
task 2

We may need to reduce j for this build, or create a jlink like option for unittest compile jobs. Another consideration is turning off GDB_INDEX which increase the link jobs by several GBs, although in the cases mentioned it seems unittest compile jobs are the main culprit.