Andy Pohl

You might find my [htcondor Docker image](https://github.com/andypohl/htcondor-docker) also useful. There is a branch called R-test with R installed. Also here it is on the [Docker Hub](https://hub.docker.com/r/andypohl/htcondor/).

I've come across something similar and learned that the POSIX threads API is always present to the XCode clang. According to the source code comments in the [AX_PTHREAD autoconf archive...