Update on OS X (Darwin) hang on my gostd fork of Joker is here: https://github.com/jcburley/joker/issues/19 tl;dr: As of around October 31, Golang changed its runtime code to use “new timer” logic that seems to interact badly with the plugin package and the Command type in os/exec, leading to intermittent hangs running the Joker test suite. The commit is not present in Go 1.13.x (so far), but has been in 1.14 from inception. gostd now excludes plugin, as a candidate package for wrapping, when building on the Darwin OS. This constitutes a workaround, not a fix!