Use sqlite3 in web worker doesn't work

[Piero87]

hi,
i'm trying to access to a sqlite3 db inside the web worker, i use this sqlite3 library:

https://github.com/mapbox/node-sqlite3

this is what i do:

var Worker = require('webworker-threads').Worker;
var worker = new Worker(function(){
  postMessage("I'm working before postMessage('ali').");
  this.onmessage = function(event) {
    console.log("before sqlite3");
    var sqlite3 = require('sqlite3').verbose();
    var db = new sqlite3.Database('MyDB.db');
    console.log("after sqlite3");
  };
});

worker.postMessage('test');

this is the result:

before sqlite3

and then block, how i can solve the problem? i do something wrong?

[audreyt]

Hi, currently we do not support require() in threads, there is only importScripts, which only supports pure-JavaScript modules (via browserify, webpack, onejs etc), and it cannot write to the filesystem.

Perhaps you could move the SQLite-access functions to the main thread, and postMessage from within the worker to access it?

[Piero87]

so you mean pass this: var db, to the worker?

[audreyt]

I mean something like:

var Worker = require('webworker-threads').Worker;
var sqlite3 = require('sqlite3').verbose();
var worker = new Worker(function(){
  this.postMessage(...) // query to db
  this.onmessage = function(event) {
      // ...handler result from SQLite3...
  };
});

var db = new sqlite3.Database('MyDB.db');
worker.onmessage = function (event) {
   // ... do something with db ...
}

Basically doing all DB filesystem operations in the main threads, and have the worker do CPU-intensive work. Something like https://github.com/mozilla/jschannel might be useful to make postMessage easier to reason with.