psysh appears to (c)lose mysqli connection #677

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1. MonsieurCellophane commented on Jul 2, 2021

   

   MonsieurCellophane

   on Jul 2, 2021

   Last edited by MonsieurCellophane

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   I put together a minimal CLI script illustrating the issue.
   This (given correct credentials: replace username and password in the code) runs to the end if invoked as php cli.php while bombing on the second and third ->ping() (and ->close) if invoked as php cli.php -d. This with either mysqli.reconnect=Off or On in php.ini

   <?php
   $options=getopt("dv",["debug","verbose"],$rst_index);
   $me=$argv[0];
   if(is_array($options)) {
       $i=0;
       while($i<$rst_index){array_shift($argv);$i++;}
       $DBG=array_key_exists('d',$options) || array_key_exists('debug',$options);
       $VERBOSE=array_key_exists('v',$options) || array_key_exists('verbose',$options);
   } else {
       error_log("Error in parsing CLI arguments:",join(',',$argv));
       die("Aborted\n");
   }
   if($DBG) {
       try {
           require('vendor/autoload.php');
       } catch (Exception $e) {
           error_log("In require: " . $e->getMessage() . "\n");
       }
   }
   $PSYSH=function_exists('psy\debug'); 
   $conn=new mysqli('localhost','root','x'); // OK
   $conn->ping();                            // OK
   if ($PSYSH) { eval(\Psy\Sh()); }
   $conn->ping();                            // FAILS with -d
   if ($PSYSH) { eval(\Psy\Sh()); }
   echo $conn->ping();                       //FAILS with -d
   $conn->close();
   
   
2. MonsieurCellophane commented on Jul 2, 2021

   

   MonsieurCellophane

   on Jul 2, 2021

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   Also:

   # php -v
   PHP 7.3.27 (cli) (built: Feb  2 2021 10:32:50) ( NTS )
   Copyright (c) 1997-2018 The PHP Group
   Zend Engine v3.3.27, Copyright (c) 1998-2018 Zend Technologies
       with Zend OPcache v7.3.27, Copyright (c) 1999-2018, by Zend Technologies
   
3. bobthecow commented on Jul 2, 2021

   

   bobthecow

   on Jul 2, 2021

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   Try disabling forking ('usePcntl' => false in psysh config ).
4. bobthecow commented on Jul 3, 2021

   

   bobthecow

   on Jul 3, 2021

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   Yep, confirmed with your repro script. It seems like mysqli doesn't play nice with forking. It's probably that one of the other threads automatically cleaned up the connection while the main thread wasn't looking?

   I've also confirmed that disabling pcntl via the psysh config fixes your issue.
5. MonsieurCellophane commented on Jul 5, 2021

   

   MonsieurCellophane

   on Jul 5, 2021

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   That's it. I can make the same happen, with no psysh in the loop, by opening a connection, forking, using it in children processes and exiting. After the first child terminates, the connection becomes useless for evey other process in the group (parent or child). I get "Mysql has gone away", not "couldn't fetch mysqli" but I think the root cause is the same. Mysql documentation mentions terminating connections on client exit, which could be the cause. I searched to see if signals are involved and, if so, ways to trap them before mysql gets wind of them, but no luck.

   👍React with 👍1Reacted by Justin Hileman
6. bobthecow commented on Feb 21, 2022

   

   bobthecow

   on Feb 21, 2022

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   Updated the Troubleshooting page of the wiki. I'm not sure what else we can do with it from our end, especially since the error happens after the shell exits? ¯_(ツ)_/¯
7. bobthecow

   closed this as completedon Feb 21, 2022