Executing jobs in Laravel via the queue is an asynchronous operation - generally once jobs are pushed onto the queue, their order of execution depends on how they're popped from the queue by the queue workers. This means that Laravel doesn't guarantee a specific order of execution when concurrently processing multiple job chains.
However, if the order of these chains is important, they should ideally be combined into a single chain. Jobs in a chain are executed in the order they are listed, and if one job fails, the rest of the chain will not be executed.
Here is an example:
Bus::chain([
new JobA(),
new JobB(),
new JobC(),
// add more Jobs here
])->dispatch();
In this chain, JobB would not be started until JobA has completed successfully, and JobC won't start until JobB completes successfully.
If you have multiple chains and need to ensure one chain is finished before starting another, you could dispatch the next chain in the final job of the previous chain.
class FinalJobOfFirstChain implements ShouldQueue
{
// ...
public function handle()
{
// ... do job's work
// Dispatch next chain.
Bus::chain([
new Job1OfSecondChain(),
new Job2OfSecondChain()
])->dispatch();
}
}
This way, the second Bus chain won't start until the first chain is finished, because the first job of the second chain is being dispatched from the final job of the first chain.
Remember: If a particular order of job execution is critical, consider whether these jobs are good candidates for queueing. Critical ordering requirements and asynchronous processing are sometimes at odds with each other.
