memory slowly leaking with high amount of tasks

[iasjennen]

hello,
I have the following use case:

a Spatie\Async\Pool instance runs permanently and processes a big amount of tasks.

This runs flawlessly, however over the course of days / weeks and processing >100000 tasks the main process requires more and more memory (>2GB).

I suspect the indefinite keeping of the history of finished processes and results causes the "memory leak", see src/Pool.php

...
$this->finished[$process->getPid()] = $process;
...
$this->results[] = $process->triggerSuccess();
...

I suggest to add explicit functions to do the house keeping, eg:

	public function clearFinished() {
		$thid->finished = [];
	}

	public function clearResults() {
		$thid->results = [];
	}

what do you think?

[iasjennen]

after a couple of days of testing i can confirm:
This was the source of the memory leak and regularly wiping the finished / results prevents the issue from happening.

Tested inside application code by wiping every 1000 jobs:

				if((intval($id) % 1000) == 0){
					$this->pool->clearResults();
					$this->pool->clearFinished();
					$this->cliOutput->printLine('wiped task worker results');
				}

[iasjennen]

@Nielsvanpach please review, when you have time

[Nielsvanpach]

We're open to accept a PR for this!