feat: Make pool size a setting per job queue

When a child process is assigned a task, the pool is restocked to this
amount. So this is the number of idle processes at any time. The total
number of processes can be higher if there are busy ones.

Author: stephanschuler

Classes/Worker.php

@@ -15,6 +15,8 @@
 use function array_shift;
 use function fputs;
 
+use function max;
+
 use const STDERR;
 use const STDOUT;
 
@@ -30,9 +32,11 @@ final class Worker
     private array $pool = [];
 
     /**
-     * A pool size of 1 means one standby while 1 is working.
+     * When a child process is assigned a task, the pool is restocked to this
+     * amount. So this is the number of idle processes at any time. The total
+     * number of processes can be higher if there are busy ones.
      */
-    protected int $poolSize = 1;
+    private readonly int $poolSize;
 
     public function __construct(
         protected readonly string $command,
@@ -42,6 +46,7 @@ public function __construct(
         protected readonly Lock $lock
     ) {
         $this->loop = EventLoop\Loop::get();
+        $this->poolSize = max(0, (int) ($queueSettings['poolSize'] ?? 1));
     }
 
     public function prepare(): void