Using Finalizers to Work Around Too many queueable jobs added to the queue: 2?

Question

I was testing Finalizer interface with Queueable apex and I think it can also be used to overcome this error: System.LimitException: Too many queueable jobs added to the queue: 2

I created a class QueueTest

public with sharing class QueueTest implements Queueable, Finalizer{

    private List<List<String>> strings;
    public QueueTest(List<List<String>> strings){
        this.strings = strings;
    }
    public void execute(FinalizerContext param1) {
        System.enqueueJob(new QueueTest1());
    }

    public void execute(QueueableContext param1) {
        QueueTest queueTest = new QueueTest(strings);
        System.attachFinalizer(queueTest);
        System.enqueueJob(new QueueTest1());
        System.debug('Queueable executed');

    }
}

and here I am firing two Queueable calls from same QueueTest class. And I dont see any error.

But when I try to fire same back to back queueable from same execute method I get the error Too many queueable jobs added to the queue: 2.

Theoretically both are same, right? Or was finalizer created to overcome such limitations?

Answer 1

Finalizer was meant to handle LimitException situations in general (too much CPU, heap, etc), as well as any uncaught exceptions, so you can recover from the situation. It is not meant to be a workaround for the too many jobs situation specifically. Note that the Finalizer itself is limited to only one additional action (a Batchable, Queueable, or @future).

Inside the execute(QueueableContext) method, execute(BatchableContext), and @future methods, you are limited to just one Queueable job per execute. If you need to do more than one Queueable in an execute, use a Scheduled job if you can, as those have normal synchronous limits (e.g. 50 Queueable/@future, multiple batches, etc).