ext/mysqli: mysqli double increments num_active_persistent when using real_connect

Description

The following code:

<?php

$use_real_connect = true;

$host = "p:localhost";
$user = "root";
$password = "password";

for ($i = 0; $i < 100; $i++)
{
  if ($use_real_connect)
  {
    $mysql = mysqli_init();
    mysqli_real_connect($mysql, $host, $user, $password);
  }
  else
  {
    $mysql = mysqli_connect($host, $user, $password);
  }
  mysqli_close($mysql);
}

$stats = mysqli_get_links_stats();
var_dump($stats);

Resulted in this output:

array(3) {
  ["total"]=>
  int(0)
  ["active_plinks"]=>
  int(99)
  ["cached_plinks"]=>
  int(1)
}

But I expected this output instead:

array(3) {
  ["total"]=>
  int(0)
  ["active_plinks"]=>
  int(0)
  ["cached_plinks"]=>
  int(1)
}

The code gives the correct output if you turn off the $use_real_connect flag.

This is caused by the persistent branch of mysqli_common_connect incrementing num_inactive_persistent (mysqli_nonapi.c:179 in tag php-8.5.8) when a persistent connection is reused based on the connection hash, then jumping to the end: label, and incrementing it again under this condition:

// mysqli_nonapi.c:296
if (persistent && (new_connection || is_real_connect)) {
    MyG(num_active_persistent)++;
}

Because mysql_close has already been called on the persisted connection, we get a total increase in active persistent connections by 1.

I'm not entirely sure why || is_real_connect is needed in that check, it looks to me like new_connection still covers the persistent case.

EDIT: The consequence of this issue is that if you make a persistent connection a ton of times (say in a long-running php-fpm process), and then make a different connection that doesn't yet exist in the connections hash table, you will always fail with the error Too many open persistent links with a massively huge number of active persistent connections. Note that this does not actually leak connections to the server, you still are capped properly by at most mysqli.max_persistent.

PHP Version

PHP 8.5.8 (cli) (built: Jul  6 2026 16:48:54) (NTS)
Copyright (c) The PHP Group
Built by https://github.com/docker-library/php
Zend Engine v4.5.8, Copyright (c) Zend Technologies
    with Zend OPcache v8.5.8, Copyright (c), by Zend Technologies

Operating System

Debian 13.5

Beginne mit ext/mysqli/mysqli_nonapi.c, insbesondere mit mysqli_common_connect und der Zählung der persistenten Verbindungen rund um die genannten Zeilen. Führe den bereitgestellten Reproducer mit aktiviertem real_connect aus und überprüfe anschließend, dass wiederholte Wiederverwendung active_plinks bei 0 und cached_plinks bei 1 belässt, ohne das Verhalten von non-real_connect zu ändern.