Child processes inherit all file descriptors

[Spacechild1]

By default, a child process created with fork inherits all open file descriptors (including all open sockets), except for those that have the FD_CLOEXEC flag set. sclang and scsynth should really set the FD_CLOEXEC on all sockets that are bound to a specific port number, otherwise a lingering child process might occupy certain ports, such as the lang port or scsynth port.

Usually, this is not a problem, but some UGens (e.g. VSTPlugin) may internally create child processes. This is particularly bad if the child processes becomes a deamon or zombie process because it may block ports indefinitely. (This once happened to me with a VST plugin on a macOS.)