javascript - How does a Node.js server process requests? -

let's assume have following code. i'm using expressjs, don't think server part different vanilla node.js.

var express=require('express');  var settings=json.parse(fs.readfilesync('settings.json','utf8')); // run once (when server starts)?  app.get('*',function(req,res){   res.write(fs.readfilesync('index.html')); // block other requests?    settimeout(function(){      someslowsynctask(); // block other requests?   },1000);    res.end(); }); 

in example above, first readfilesync run once when server starts, or run each time server receives request?

for second readfilesync, prevent node processing other requests? in other words, other requests have wait until readfilesync finishes before node processes them?

edit: added settimeout , someslowsynctask. block other requests?

you should avoid synchronous methods on server. available convenience single user utility scripts.

the first 1 runs once since synchronous method. * route not setup until after returns.

the second run when http request comes server. , yes, block whole server duration of synchronous call (i/o cost open , read contents of file). don't that.

there plenty of articles on internet around understanding node event loop. example, here , here