Concurrency fails in Livewire with an unserialize error

I've set up a livewire component and when I pass a variable into a Concurrency call it fails. unserialize(): Error at offset 157 of 387 bytes As I understand it the function is serialized first before being processed.

I suspect this is to do with the limitations of Livewire and how it passes data around interfering with how the concurrency serialization is done. Is anyone able to shed a little light? In the code below replacing the reference to $this->newPiece with a string fixes the problem but removes the ability to make the value dynamic.

class ConcurrentTest extends Component
{
	public $newPiece = 'King';
	public $pieces = ['pawn','bish'];

	public function render()
	{
		return view('livewire.concurrent-test');
	}

	public function mount()
	{
		[$this->pieces[], $this->pieces[]] = Concurrency::run([
			fn() =>  'Draught',
			fn() =>  $this->newPiece
		]);
	}
}

I'm thinking I might have to make my concurrent call a Http post to a separate endpoint but I'd rather avoid that if there's a better solution.

LaryAI

8 months ago

Best Answer

Level 58

The issue you’re encountering is due to how PHP closures (anonymous functions) are serialized when using concurrency helpers (like Laravel’s Bus::batch, Laravel Octane, or similar concurrency libraries). In your code, the closure fn() => $this->newPiece captures the $this context (the Livewire component instance), which is not serializable by default. Livewire serializes the component state between requests, and when it tries to serialize the closure (which references $this), it fails, resulting in the unserialize(): Error at offset... error.

Why does replacing $this->newPiece with a string work?
Because the closure no longer captures the $this context, making it serializable.

Solution

Extract the dynamic value before passing it into the closure.
Assign the value you want to use to a local variable, and then use that variable inside the closure. This way, the closure does not capture the Livewire component instance.

Here’s how you can modify your code:

class ConcurrentTest extends Component
{
    public $newPiece = 'King';
    public $pieces = ['pawn','bish'];

    public function render()
    {
        return view('livewire.concurrent-test');
    }

    public function mount()
    {
        $newPiece = $this->newPiece; // Extract the value to a local variable

        [$this->pieces[], $this->pieces[]] = Concurrency::run([
            fn() => 'Draught',
            fn() => $newPiece // Use the local variable, not $this
        ]);
    }
}

Key Point:
Avoid referencing $this inside closures that will be serialized for concurrency. Always extract the needed data into local variables first.

If you need to update $this->pieces dynamically based on the result, do so after the concurrency call:

public function mount()
{
    $newPiece = $this->newPiece;

    $results = Concurrency::run([
        fn() => 'Draught',
        fn() => $newPiece
    ]);

    $this->pieces[] = $results[0];
    $this->pieces[] = $results[1];
}

Summary:

Don’t reference $this inside closures passed to concurrency helpers.
Extract any needed data into local variables first.
Use those variables inside your closures.

This should resolve the serialization error you’re seeing!