feat(cron): Warn on excessive memory consumption in background jobs

Signed-off-by: Joas Schilling <coding@schilljs.com>

cron.php

@@ -149,8 +149,22 @@ try {
 			}
 
 			$logger->debug('CLI cron call has selected job with ID ' . strval($job->getId()), ['app' => 'cron']);
+
+			$memoryBefore = memory_get_usage();
+			$memoryPeakBefore = memory_get_peak_usage();
+
 			$job->execute($jobList, $logger);
 
+			$memoryAfter = memory_get_usage();
+			$memoryPeakAfter = memory_get_peak_usage();
+
+			if ($memoryAfter - $memoryBefore > 10_000_000) {
+				$logger->warning('Used memory grew by more than 10 MB when executing job ' . get_class($job) . ' : ' . \OCP\Util::humanFileSize($memoryAfter). ' (before: ' . \OCP\Util::humanFileSize($memoryBefore) . ')', ['app' => 'cron']);
+			}
+			if ($memoryPeakAfter > 300_000_000) {
+				$logger->warning('Cron job used more than 300 MB of ram after executing job ' . get_class($job) . ': ' . \OCP\Util::humanFileSize($memoryPeakAfter) . ' (before: ' . \OCP\Util::humanFileSize($memoryPeakBefore) . ')', ['app' => 'cron']);
+			}
+
 			// clean up after unclean jobs
 			\OC_Util::tearDownFS();
 			$tempManager->clean();