Enqueue Queueable class multiple times

Question

I need to do five different callouts from my trigger. I'm planning to use one Queueable class for all the callout using the parameter passed in the constructor. I'm not sure if it is possible, if it is then can I do parallel enqueue like:

System.enqueueJob(new QueueableClass(newList[0]));
System.enqueueJob(new QueueableClass(newList[0]));
System.enqueueJob(new QueueableClass(newList[0]));
System.enqueueJob(new QueueableClass(newList[0]));

or do I need to chain it. if its not possible then, I guess I need to create new class for each callout.

Answer 1

This pattern is likely to cause tricky-to-debug issues in the future.

When your trigger is invoked via updates made in a Batch Apex class, you will get an exception stating that you've enqueued too many jobs at 2.

Too many queueable jobs added to the queue: 2

As you may know, the limit per transaction is 50 (so if you're enqueuing five Queueables per trigger record - I see newlist[0] in there - you're already in trouble with regular trigger operation). However, an Apex Batch context only allows enqueuing one job, not 50.

As a result, down the road when you write a Batch that directly or indirectly affects this object, you'll start to get these mysterious failures when the trigger runs and tries to enqueue so many Queueables.

For more, see this question and answer.

You should use a chaining pattern here. If your callouts are not idempotent, you also need to be very careful about the possibility of trigger recursion.