PDOPool does not reconnect on connection timeout.

[intellent]

1. What did you do? If possible, provide a simple script for reproducing the error.

Created a MySQL PDOPool to fetch connections with PDOPool::get() and put them back with PDOPool::put($con) after the HTTP response has been served. wait_timeout of the DBMS is very low (60 seconds), but this problem also occurs with larger values, only later.

2. What did you expect to see?

I expect PDOPool::get() to return a working connection and check for terminated connections.

3. What did you see instead?

After some successful connections and waiting for the connection timeout to occur PDOPool::get() returns a terminated connection resulting in error 2006 MySQL server has gone away

4. What version of Swoole are you using?

Swoole => enabled
Author => Swoole Team team@swoole.com
Version => 4.6.4
Built => Apr 8 2021 18:15:20
coroutine => enabled with boost asm context
epoll => enabled
eventfd => enabled
signalfd => enabled
spinlock => enabled
rwlock => enabled
mutex_timedlock => enabled
pthread_barrier => enabled
async_redis => enabled

Directive => Local Value => Master Value
swoole.enable_coroutine => On => On
swoole.enable_library => On => On
swoole.enable_preemptive_scheduler => Off => Off
swoole.display_errors => On => On
swoole.use_shortname => On => On
swoole.unixsock_buffer_size => 8388608 => 8388608

5. What is your machine environment used?

Linux 1100dd632f36 4.19.121-linuxkit #1 SMP Thu Jan 21 15:36:34 UTC 2021 x86_64 Linux

PHP 8.0.3 (cli) (built: Apr 1 2021 15:27:33) ( NTS )
Copyright (c) The PHP Group
Zend Engine v4.0.3, Copyright (c) Zend Technologies

[intellent]

I’ve tried working around this issue by catching the PDOException 2006 MySQL server has gone away. How can I remove a terminated connection from PDOPool?

[sy-records]

If an exception occurs, you can put null back into the pool.

try {

} catch (\Throwable $e) {
    $pool->put(null);
}

[TorstenDittmann]

@intellent just wanna mention how I solved this exact problem here #4131 (comment)