Close client connections on SIGINT/SIGTERM

[kulshekhar]

Fixes #2875

Currently, express doesn't shut down immediately after receiving SIGINT/SIGTERM if it has client connections that haven't timed out. (This is a known issue with node)

This PR intends to fix this behavior such that parse server will close all open connections and initiate the shutdown process as soon as it receives a SIGINT/SIGTERM signal.

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[flovilmart]

One small nit but that should do.
Could you add the link to the node-js issue around for posterity

[flovilmart]

Add trailing:

[kulshekhar]

Something like this?

  function initializeConnections(socket) {
    /* Currently, express doesn't shut down immediately after receiving SIGINT/SIGTERM if it has client connections that haven't timed out. (This is a known issue with node - https://github.com/nodejs/node/issues/2642)

      This intends to fix this behavior such that parse server will close all open connections and initiate the shutdown process as soon as it receives a SIGINT/SIGTERM signal. */

    const socketId = socket.remoteAddress + ':' + socket.remotePort;

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[flovilmart]

Awesome!

[mmarshak]

@flovilmart I integrated a job scheduler in the same server that Parse server use, I am using Kue-Scheduler. In order to prevent stuck jobs with Kue I had my own code that detect when there is SIGINT/SIGTERM and does a clean shutdown of Kue (radis based connection) by calling -

Queue.shutdown( shutDownTimout, function(err){
console.log("Kue Shutdown completed result ", err || "ok" );
process.exit(0);
}

Now Parse handing of SIGINT/SIGTERM is independent of Kue handling of shutdown and one can decided to exist earlier before the other.

It will be very helpful if there was some hook (function) that Parse server will before it actually call process.exit() and allow other connections to close cleanly before Parse call exit().