I use Antora 2.3 since sometime now and I had to introduce more source repositories into my playbook.yaml file as the documentation-site grew.
Currently, I have 50-60 Git repos, each of size around 15 MB, mentioned in the playbook.
Afterwards, my site generation began to crash while parallelly cloning the repositories mentioned in my content.sources[] of playbook.yaml (i.e. exits from the Antora command in Linux shell without any errors).
I tried allocating more memory and received same above issue
node --max-old-space-size=16384 `which antora` --cache-dir=./.cache/antora --generator custom-generate-site playbook.yaml --stacktrace