MaxListenersExceededWarning - Loopback

Question

I am getting the following error:

 (node:18591) MaxListenersExceededWarning: Possible EventEmitter memory 
leak detected. 11 wakeup listeners added. Use emitter.setMaxListeners() to increase limit.

after a script for sending push notifications is executed. I am using "node-gcm" and "apn" npm modules for sending android and ios push notifications respectively. Code that I am using for sending notifications is:

Android:

async.each(tokenBatches, function (batch) {
// Assuming you already set up the sender and message
   sender.send(message, {registrationIds: batch}, function (err, result) {
    // Push failed?
    if (err) {
    // Stops executing other batches
        console.log(err);
    }
    console.log(result);
    });
});

Here, device tokens are passed as a batch of 1000 tokens.

IOS:

provider.send(notification, iosTokens).then((response) => {
   console.log(response);
});

Here, all tokens are sent inside the iosTokens array. These two scripts are run in parallel. What could be wrong in this code? I saw some solutions asking to set max listeners, but I am not getting it right. Is there any way to fix the memory leak error. Any help would be appreciated! Thanks in advance.