Bruno Haible <br...@clisp.org> wrote: > Hi Eric, > > Eric Wong wrote: > > I would've recommended just using a pipe, socket or eventfd; > > How would setting up a pipe or eventfd help with a communication > problem between threads in the same process? I thought these were > for communication between processes.
The "self-pipe trick" is a common idiom in Unix for signal handling; especially when pselect/ppoll aren't available. I seem to recall learning of it reading something by djb. It's perfectly valid to use pipes in single-threaded or multi-threaded, or multi-process situations. POSIX gives well-defined semantics w.r.t. atomicity. I know the (C)Ruby VM uses it internally (or eventfd on Linux); I think CPython's GVL does, too. My gnulib-using cmogstored uses a self-pipe when epoll_pwait isn't available (Though it could probably use EVFILT_SIGNAL on *BSD).
