To expand on this Linux threads, NPTL and fork() all call clone() under modern Linux and glibc. The flags on that call and mostly what is inherited or dropped

To expand on this Linux threads, NPTL and fork() all call clone() under modern Linux and glibc. The flags on that call and mostly what is inherited or dropped is the main difference. Add in pid remapping with namespaces in containers and it is common for people to go on wild goose chases if they assume that the legacy fork() model is in play.