EZP-32184: Added warning about possible memory leaks for reindex command

eZ/Bundle/EzPublishCoreBundle/Command/ReindexCommand.php

@@ -6,6 +6,7 @@
  */
 namespace eZ\Bundle\EzPublishCoreBundle\Command;
 
+use Symfony\Component\Console\Style\SymfonyStyle;
 use function count;
 use const DIRECTORY_SEPARATOR;
 use Doctrine\DBAL\Connection;
@@ -209,6 +210,20 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             );
             $this->searchIndexer->createSearchIndex($output, (int) $iterationCount, !$commit);
         } else {
+            $io = new SymfonyStyle($input, $output);
+            $io->warning(<<<EOT
+                For optimal performance, before running this command, make sure that:
+                - the xdebug extension is disabled,
+                - you're running the command in "prod" environment,
+                - memory limit for big databases is set to "-1" or an adequately high value,
+                - --iteration-count is low enough (default: 50),
+                - number of processes for parallel batch operations is high enough (default: 'auto' is a good choice).
+            EOT);
+
+            if (!$io->confirm('Continue?', true)) {
+                return 0;
+            }
+
             $output->writeln('Re-indexing started for search engine: ' . $this->searchIndexer->getName());
             $output->writeln('');