Option to send messages in bulk

[tankorbox]

I see your idea in _messages on ChannelWrapper is data preserving. But i realized that the performance is low (in my system only ~300msgs/s rate from producer to RabbitMQ) - One message can only be sent after previous message has callback return. Any option to send message in bulk asynchorous without waiting others. Or you can suggest me some properly way to do this. Thank you so much.

[jwalton]

You can send multiple messages without waiting for the callback to return. For example:

for(const message of messages) {
    await channel.publish(...);
}

Will send each message sequentially, waiting for each to be finished, but:

for(const message of messages) {
    channel.publish(...).catch(err => console.log("Bad things happened. :(");
}

Will fire off all your messages at once, since we're not awaiting each one. You could also do something like:

await Promise.all(messages.map(message => channel.publish(...)));

Which will send a big block of messages all at once, wait for all of them to be successfully delivered, and error back if any one of them fails (although, you don't know which ones failed in this case).

[tankorbox]

Thank you so much for responses. I successfully apply new implement to send multiple messages. The app's performance improved perfectly. But I have a problem. when a large number of request call sendToQueue, node app reached max heap and die. Would you mind raising any solution for this case?
And I have one question about your code implementation. Why did you call publishQueueMessage recursive. It may be more heavier than using loop??

[jwalton]

_publishQueuedMessages isn't really recursive - it calls itself from inside the Promise().then(), which is always resolved after a call to setImmediate(), so it's not as if this is going to blow the stack or anything. But, reaching max heap certainly sounds bad. :P

[jwalton]

Fixed by #84.