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Bug #78972 Using disconnected PDO connection causes suppressed EPIPE notice
Submitted: 2019-12-16 16:15 UTC Modified: 2020-12-11 14:37 UTC
Avg. Score:5.0 ± 0.0
Reproduced:2 of 2 (100.0%)
Same Version:1 (50.0%)
Same OS:2 (100.0%)
From: xzzll at msn dot cn Assigned: nikic (profile)
Status: Closed Package: PDO Core
PHP Version: 7.3.12 OS: Centos7
Private report: No CVE-ID: None
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From: xzzll at msn dot cn
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 [2019-12-16 16:15 UTC] xzzll at msn dot cn
Errors in some cases when pdo ends the connection.

I can't locate the details of this issue for now because it happens randomly.

The demo code I provided is almost the same as the actual business code, they work persistently under cli and perform close and reopen on timeout connections.

However, the connection may be interrupted automatically due to network fluctuations or server timeouts.When the mysql connection in some processes is persistent and no activity is triggered again, an exception occurs.(My mysql server is remote)

Msg : \Game\Sql\Pdo::close(): send of 5 bytes failed with errno=32 Broken pipe

Since the demo code is more than 20 lines, I scaled it. Please format it and view it. I am very sorry for the trouble.

It is important to note that this problem does not absolutely recur, it happens randomly, and when the problem occurs, it is in a long-term vacant state.

Test script:
namespace test;class Pdo{public static $db;public static $start;public static $timeout;
    public static function init($config){try {
            self::$db = new \PDO('mysql:dbname=' . $config['table'] . ';host=' . $config['server'] . ';port=' . $config['port'] . ';charset=utf8', $config['user'], $config['password'], [
                \PDO::ATTR_PERSISTENT => false,
        } catch (\Throwable $th) {var_dump($th);return;}
        self::$start   = time();self::$timeout = (self::$db->query('show variables like "wait_timeout"')->fetch(MYSQLI_ASSOC))['Value'];
        echo ("-------------------MYSQLConnect timeout=" . self::$timeout . " ServerVersion=" . self::$db->query('select version()')->fetchColumn() . "-------------------");}
    public static function close(){self::$db = null;}
    public static function uinit(){self::close();$time = microtime(true);echo ("-------------------ReConnect:" . $time . "-------------------");self::init(require(__DIR__ . '/think/config/MysqlConfig.php'));echo ("-------------------ConnectOk:" . (microtime(true) - $time) . "-------------------");}
    public static function test(){if (time() - self::$start >= self::$timeout) {$this->uinit();}}
\test\Pdo::init(require_once __DIR__ . '/think/config/MysqlConfig.php');
sleep(\test\Pdo::$timeout + 10); //The time here should actually be very long
\test\Pdo::test(); //error 
/*SyStemNotice:Code:   8
File: /root/Game/think/system/Sql/Pdo.php:29
Msg : \Game\Sql\Pdo::close(): send of 5 bytes failed with errno=32 Broken pipe*/

Expected result:
Ideally, it should close the connection normally, or end directly when the connection is unavailable, so that the code can continue to perform the connection work, but in fact it throws a notice error

Actual result:
Code:   8
File: /root/Game/think/system/Sql/Pdo.php:29
Msg : \Game\Sql\Pdo::close(): send of 5 bytes failed with errno=32 Broken pipe


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 [2020-10-29 13:31 UTC]
-Status: Open +Status: Verified
 [2020-10-29 13:31 UTC]
Here is a reduced reproducer:


set_error_handler(function(...$args) { 
$db = new \PDO('mysql:unix_socket=/var/run/mysqld/mysqld.sock;dbname=test', 'root', '', [ 
$db->exec('SET session wait_timeout=1');
$db = null;

Something worth noting is that the broken pipe error is actually suppressed with error_reporting=0, but of course it can still be seen by a custom error handler. It would be better to suppress it more thoroughly.
 [2020-10-29 13:42 UTC]
-Summary: Pdo close error +Summary: Using disconnected PDO connection causes suppressed EPIPE notice
 [2020-10-29 13:42 UTC]
I don't think we have a good mechanism to suppress this more thoroughly right now.

It should be said that any error handler that does not ignore errors disabled by the current error_reporting level is a buggy error handler. While it would be nice to improve the behavior here on the mysqlnd side, the bug is ultimately in the custom error handler.
 [2020-12-11 14:37 UTC]
-Status: Verified +Status: Closed -Assigned To: +Assigned To: nikic
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