Add max processes config value

app.js

@@ -2,11 +2,14 @@
 /* eslint no-console: ["error", { allow: ["log", "error"] }] */
 
 const cluster = require('cluster');
+const config = require('./app/models/config-model');
 const numCPUs = require('os').cpus().length;
 
+const numProcesses = Math.min(config.server['max processes'], numCPUs);
+
 if (cluster.isMaster) {
     // Fork workers.
-    for (let i = 0; i < numCPUs; i++) {
+    for (let i = 0; i < numProcesses; i++) {
         cluster.fork();
     }
 

config/default-config.json

@@ -1,6 +1,7 @@
 {
     "app name": "Enketo Smart Paper for KoBoCAT",
     "port": "8005",
+    "max processes": 16,
     "offline enabled": true,
     "id length": 8,
     "linked form and data server": {

tutorials/10-configure.md

@@ -25,6 +25,10 @@ Just used in home page `"Enketo for [your service name]"`..
 
 The port on which your app is run, e.g. `"8005"`. Any unique assignable port will do. Generally you can leave this alone as you'll use a reverse proxy to map the public port.
 
+#### max processes
+
+The max number of processes Enketo will serve. Enketo will not serve more processes than the number of cpus available. Defaults to `16`.
+
 #### offline enabled
 
 Enable or disable offline functionality. Is either `false` or `true`.