Question: Is there a way in app that we can detect current running core?

[vuhpham]

I'm running to an issue that I have an Mongo update query in startup code of server:

if (Meteor.isServer) {
 Meteor.startup(function(){
    Posts.find().observeChanges({
        added: function(id, fields) {
            Authors.update({_id: fields.authorId}, {$inc: {count: 1}});
        }
    })
 });
}

I run app with 4 cores server and this added event run 4 times which I expected just 1.
Is there a way in app that we can detect current running core? Or any other best practices to run observerChanges in multicore environment?

[arunoda]

It's very tricky to run these kind of stuff. This is not only for cores,
think what will be happen when you are running multiple servers of your app.

Here's a way to to that.

• Inside every worker there's a env variable called CLUSTER_WORKER_ID.
  Try to create the observer when there is no such worker
• When you are running multiple servers, expose a new env for only one
  server. And check for that env as well.
• So, this observer runs on a single server and single core.

You can even look at some other stuffs like, doing these things as a job
queue or running different app.

On Fri, May 1, 2015 at 1:49 AM Vu Pham notifications@github.com wrote:

I'm running to an issue that I have an Mongo update query in startup code
of server:

if (Meteor.isServer) {
Meteor.startup(function(){
Posts.find().observeChanges({
added: function(id, fields) {
Authors.update({_id: fields.authorId}, {$inc: {count: 1}});
}
})
});
}

I run app with 4 cores server and this added event run 4 times which I
expected just 1.
Is there a way in app that we can detect current running core? Or any
other best practices to run observerChanges in multicore environment?

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Reply to this email directly or view it on GitHub
#51.

[vuhpham]

Thanks @arunoda I think I'd better run this in a microservice then.
However that env variable is nice as well. 👍