Requirejs does not load module synchronously when a context based config is used

[khirakawa]

StackOverflow link

When using context based configs, requirejs does not load modules synchronously as suggested by the docs:

"... when running in Node, module loading will be loaded using sync IO calls, and loader plugins should resolve calls to their load method synchronously."

Here's my test case:

A.js

define([], function() {
    return {test: "test"};
}

spec.js

var requirejs = require('requirejs');

var localReq = requirejs.config({
    baseUrl: "./",
    context: "context1"
})

describe("context test", function () {
    it("should not throw error", function () {
        for (var i = 0; i < 100; i++) {
            console.log(localReq("A"), i);
        }
    });
});    

When I run the test mocha spec.js, I get the following error:

Uncaught Error: Tried loading "A" at /Users/khirakawa/work/test/node_modules/mocha/bin/A.js then tried node's require("A") and it failed with error: Error: Cannot find module 'A'

Interestingly, {test: 'test1'} gets logged 100 times, which seem to suggest that synchronous loading is happening, but there also seems to be something else going on that causes this issue.

Some other observations:

• If I use an absolute path to A, then it works just fine. i.e. localReq("/Users/khirakawa/work/test/A.js")
• If I use the default context of "_", it works just fine.
• I also ran into a similar behavior with jasmine, suggesting that this is more of a requirejs issue.
• I also modified tests/node/syncRequire/main.js to use a context. The test failed.

Here's my modified main.js test

var requirejs = require('../../../r.js');

var localReq = requirejs.config({
    nodeRequire: require,
    context: "A"
});

var a = localReq('a');

console.log('syncRequire A ' + (a.name === 'a' ? 'PASSED' : 'FAILED'));
console.log('syncRequire A ' + (a.getB().name === 'b' ? 'PASSED' : 'FAILED'));

a is undefined.

Would be great to know why this happens. Thanks!

[jrburke]

This error:

Uncaught Error: Tried loading "A" at /Users/khirakawa/work/test/node_modules/mocha/bin/A.js then tried node's require("A") and it failed with error: Error: Cannot find module 'A'

Seems to indicate that it tried to load, but was just at the wrong path. I think the issue is that baseUrl: __dirname in the requirejs config is needed. Otherwise, './' will match the current directory of whatever runs the test, which looks like it might be mocha's bin directory.

Closing as I think that is the issue, but feel free to continue discussion here and we can reopen if there is another issue.

[lddubeau]

@jrburke , I can reproduce this problem even when using __dirname. One thing though, which I've just discovered now, is that the problem is intermittent. You can do 5 runs without error and the 6th is going to fail. The first time I tried to reproduce this issue (days ago), I was able to reproduce it every single time. Today I get many runs without an issue so there's probably a timing component (maybe the load on my machine changed between the two times I tried). It is also more likely to occur with longer loops.

And here is something that I find puzzling. Even if the interpretation of baseUrl's value were to change during the run, all the calls that load A are of the synchronous form. So they should fail immediately, no? But the error is appearing after all localReq calls have successfully returned a value. So where is the error coming from?

[jrburke]

@lddubeau if you have a test case I can try, that will likely be the easiest way to get to the issue.

[lddubeau]

@jrburke Sure! Here's a repo with what I've been running. It is essentially the same as khirakawa's A.js and spec.js tests except that:

1. My A.js returns "foo" instead of an object.
2. I use __dirname.
3. My loop goes to 1000 instead of 100.

[jrburke]

Putting this in 2.1.12 bucket for further triage, not sure if it will make 2.1.12 though, or the root cause yet.