Use "pcntl_fork" to fork processes

bin/daemon.php

@@ -29,6 +29,7 @@ if (php_sapi_name() !== 'cli') {
 }
 
 use Dice\Dice;
+use Friendica\App\Mode;
 use Friendica\Core\Logger;
 use Friendica\Core\Worker;
 use Friendica\Database\DBA;
@@ -65,6 +66,8 @@ if (DI::mode()->isInstall()) {
 	die("Friendica isn't properly installed yet.\n");
 }
 
+DI::mode()->setExecutor(Mode::DAEMON);
+
 DI::config()->load();
 
 if (empty(DI::config()->get('system', 'pidfile'))) {
@@ -144,34 +147,35 @@ Logger::notice('Starting worker daemon.', ["pid" => $pid]);
 if (!$foreground) {
 	echo "Starting worker daemon.\n";
 
-	// Switch over to daemon mode.
-	if ($pid = pcntl_fork()) {
-		return;     // Parent
-	}
-
-	fclose(STDIN);  // Close all of the standard
-
-	// Enabling this seem to block a running php process with 100% CPU usage when there is an outpout
-	// fclose(STDOUT); // file descriptors as we
-	// fclose(STDERR); // are running as a daemon.
-
 	DBA::disconnect();
 
+	// Fork a daemon process
+	$pid = pcntl_fork();
+	if ($pid == -1) {
+		echo "Daemon couldn't be forked.\n";
+		Logger::warning('Could not fork daemon');
+		exit(1);
+	} elseif ($pid) {
+		// The parent process continues here
+		echo 'Child process started with pid ' . $pid . ".\n";
+		Logger::notice('Child process started', ['pid' => $pid]);
+		file_put_contents($pidfile, $pid);
+		exit(0);
+	}
+
+	// We now are in the child process
 	register_shutdown_function('shutdown');
 
+	// Make the child the main process, detach it from the terminal
 	if (posix_setsid() < 0) {
 		return;
 	}
 
-	if ($pid = pcntl_fork()) {
-		return;     // Parent
-	}
-
-	$pid = getmypid();
-	file_put_contents($pidfile, $pid);
+	// Closing all existing connections with the outside
+	fclose(STDIN);
 
-	// We lose the database connection upon forking
-	DBA::reconnect();
+	// And now connect the database again
+	DBA::connect();
 }
 
 DI::config()->set('system', 'worker_daemon_mode', true);

bin/worker.php

@@ -28,7 +28,7 @@ if (php_sapi_name() !== 'cli') {
 
 use Dice\Dice;
 use Friendica\App;
-use Friendica\Core\Process;
+use Friendica\App\Mode;
 use Friendica\Core\Update;
 use Friendica\Core\Worker;
 use Friendica\DI;
@@ -59,6 +59,8 @@ $dice = $dice->addRule(LoggerInterface::class,['constructParams' => ['worker']])
 DI::init($dice);
 $a = DI::app();
 
+DI::mode()->setExecutor(Mode::WORKER);
+
 // Check the database structure and possibly fixes it
 Update::check($a->getBasePath(), true, DI::mode());
 

index.php

@@ -36,6 +36,8 @@ $dice = $dice->addRule(Friendica\App\Mode::class, ['call' => [['determineRunMode
 
 $a = \Friendica\DI::app();
 
+\Friendica\DI::mode()->setExecutor(\Friendica\App\Mode::INDEX);
+
 $a->runFrontend(
 	$dice->create(\Friendica\App\Module::class),
 	$dice->create(\Friendica\App\Router::class),

src/App/Mode.php

@@ -38,6 +38,11 @@ class Mode
 	const DBCONFIGAVAILABLE   = 4;
 	const MAINTENANCEDISABLED = 8;
 
+	const UNDEFINED = 0;
+	const INDEX = 1;
+	const DAEMON = 2;
+	const WORKER = 3;
+
 	const BACKEND_CONTENT_TYPES = ['application/jrd+json', 'text/xml',
 		'application/rss+xml', 'application/atom+xml', 'application/activity+json'];
 
@@ -47,6 +52,12 @@ class Mode
 	 */
 	private $mode;
 
+	/***
+	 * @var int Who executes this Application
+	 *
+	 */
+	private $executor = self::UNDEFINED;
+
 	/**
 	 * @var bool True, if the call is a backend call
 	 */
@@ -163,6 +174,31 @@ class Mode
 		return ($this->mode & $mode) > 0;
 	}
 
+	/**
+	 * Set the execution mode
+	 *
+	 * @param integer $executor Execution Mode
+	 * @return void
+	 */
+	public function setExecutor(int $executor)
+	{
+		$this->executor = $executor;
+
+		// Daemon and worker are always backend
+		if (in_array($executor, [self::DAEMON, self::WORKER])) {
+			$this->isBackend = true;
+		}
+	}
+
+	/*isBackend = true;*
+	 * get the execution mode
+	 *
+	 * @return int Execution Mode
+	 */
+	public function getExecutor()
+	{
+		return $this->executor;
+	}
 
 	/**
 	 * Install mode is when the local config file is missing or the DB schema hasn't been installed yet.

src/Core/Worker.php

@@ -21,6 +21,7 @@
 
 namespace Friendica\Core;
 
+use Friendica\App\Mode;
 use Friendica\Core;
 use Friendica\Database\DBA;
 use Friendica\DI;
@@ -1180,6 +1181,44 @@ class Worker
 		self::killStaleWorkers();
 	}
 
+	/**
+	 * Fork a child process
+	 *
+	 * @param boolean $do_cron
+	 * @return void
+	 */
+	private static function forkProcess(bool $do_cron)
+	{
+		// Children inherit their parent's database connection.
+		// To avoid problems we disconnect and connect both parent and child
+		DBA::disconnect();
+		$pid = pcntl_fork();
+		if ($pid == -1) {
+			DBA::connect();
+			Logger::warning('Could not spawn worker');
+			return;
+		} elseif ($pid) {
+			// The parent process continues here
+			DBA::connect();
+			Logger::info('Spawned new worker', ['cron' => $do_cron, 'pid' => $pid]);
+			return;
+		}
+	
+		// We now are in the new worker
+		DBA::connect();
+		Logger::info('Worker spawned', ['cron' => $do_cron, 'pid' => getmypid()]);
+
+		DI::process()->start();
+
+		self::processQueue($do_cron);
+
+		self::unclaimProcess();
+
+		DI::process()->end();
+		Logger::info('Worker ended', ['cron' => $do_cron, 'pid' => getmypid()]);
+		exit();
+	}
+
 	/**
 	 * Spawns a new worker
 	 *
@@ -1189,13 +1228,15 @@ class Worker
 	 */
 	public static function spawnWorker($do_cron = false)
 	{
-		$command = 'bin/worker.php';
-
-		$args = ['no_cron' => !$do_cron];
-
-		$a = DI::app();
-		$process = new Core\Process(DI::logger(), DI::mode(), DI::config(), DI::modelProcess(), $a->getBasePath(), getmypid());
-		$process->run($command, $args);
+		// Worker and daemon are started from the command line.
+		// This means that this is executed by a PHP interpreter without runtime limitations
+		if (in_array(DI::mode()->getExecutor(), [Mode::DAEMON, Mode::WORKER])) {
+			self::forkProcess($do_cron);
+		} else {
+			$process = new Core\Process(DI::logger(), DI::mode(), DI::config(),
+				DI::modelProcess(), DI::app()->getBasePath(), getmypid());
+			$process->run('bin/worker.php', ['no_cron' => !$do_cron]);
+		}
 
 		// after spawning we have to remove the flag.
 		if (DI::config()->get('system', 'worker_daemon_mode', false)) {