3.1.2 Set the PTY fd to be non-blocking #36
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lhchavez
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nodejs/node#42826 seems to imply that setting O_NONBLOCK on controller side fd is ok, our original issue of fcntl F_DUPFD_CLOEXEC failed: bad file descriptor (os error 9) is probably due to how we set autoClose before
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We have gone back and forth a couple of times, but we _do_ need to set this FD to be non-blocking. Otherwise node will fully consume one I/O thread for each PTY, and node only has four of those. This change makes the controller fd (the one the parent process reads from / writes to) as non-blocking for node. Also, now that the controller fd is non-blocking, we need to pass it through Node's TTY machinery so that it is properly handled. Because of that, Rust is no longer on the hook for closing the FD, since ownership is fully transferred to Node.
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We have gone back and forth a couple of times, but we do need to set this FD to be non-blocking. Otherwise node will fully consume one I/O thread for each PTY, and node only has four of those.
This change makes the controller fd (the one the parent process reads from / writes to) as non-blocking for node.