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NodeJS child_process spawning experiments (blocking/streaming/signals)
child_process_experiments's Introduction
NodeJS child process experiments
- spawning child (and sub) processes
- blocking processes (stream + timers)
- sending signals
- pipes for stdin/stdout+stderr are established between the parent Node.js process and the spawned child
- holding process/shell open:
- timers + stream (of data, via TCP sockets) hold it
- spawn(process.execPath, args) -> holds (stream)
- process.stdout.on('data') -> holds (stream)
- same applies to parent or child process
- setTimeout(() => { /* code */ }, 1000) - holds (timer)
- process.on('SIGINT') -> doesnt hold (not a stream, an event)
- WHY:
- child process waits to read all of its input
- the child will not continue until the stream has been closed via end() or kill().
- process.stdin.end() OR process.kill('SIGINT')
- can pass kill event down stack i.e. parent -> child -> baby
- 'EXIT' event - emitted after the child process ends
- IF nothing holding process will always run at end of script
- ELSE signal could manually have exited it, will have signal.
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