Stream data of backup for less memory usage

src/Service/BackupService.php

@@ -21,15 +21,22 @@ class BackupService
             $fileName = sprintf('%s_%s_backup.sql', $db, $date);
         }
 
-        $filesystem = new Filesystem();
         $process = new Process([
             'mysqldump',
             '-u', $this->credentials->getUser(),
             $db,
         ]);
         $process->setEnv(['MYSQL_PWD' => $this->credentials->getPassword()]);
-        $process->run();
-        $filesystem->dumpFile($fileName, $process->getOutput());
+        $process->start();
+
+        $stream = fopen($fileName, 'w+');
+        foreach ($process as $type => $data) {
+            if ($process::OUT === $type) {
+                fwrite($stream, $data);
+            } else { // $process::ERR === $type
+                echo "\nError: " . $data;
+            }
+        }
 
         return $fileName;
     }