Execute function on interval only if server is not under heavy load

Question

Execute function on interval only if server is not under heavy load

I'm performing a routine check on my DB every hour or so by doing

setInterval(function() {
  myCheckFunction();
}, 3600000)

I'm thinking of something like :

setInterval(function() {
  server.getConnections(function(err, count) {
    if (count < X) {
      myCheckFunction();
    }
}, 3600000)

To check if there's isn't too much work being done right now.

Is it a good idea ? If so what value could X have ? If not, should I try differently or just do the test, non regarding of the current load ?

I don't expect millions of connections, this is just a proof of concept and my teacher asked me to take care of that kind of things.

Thanks !

Edit: Why do I want to avoid heavy load ? Because the routine check could take a couple of minutes and require a lot of work for the server. It has to contact at least 5 DNS server for each entry in the DB, request HTML code and hash it, then compare answers. The check for one entry can take up to 6 seconds due the the fact that the DNS servers can be Timeout and the DB is hosted separately from the project.

javascript
node.js
express

Answer 1

This is what you are looking for:

toobusy

Answer 2

With this particular requirements, I would perform this check on server side instead.

var checkFunctionCaller = function () {
    //call async function on server side and provide a callback function
    //to be called as server returns an answer
    server.myCheckFunction(function (result) {
        // if server was able to run check - it return 'done' and everything is fine
        if(result === "done") {
          //do nothing
        }
        //otherwise, re-schedule a check in five minutes
        setTimeout(checkFunctionCaller, 5 * 60 * 1000);
    });
}


setInterval(checkFunctionCaller, 3600000);