Cannot write session to redis storage

[Max Wagner]

Hallo,

we use the amphp/http-server to run a Long-running PHP Webserver. For session handling we use the amphp/http-server-session package and this package to store session data in redis. Our system and solution works like expected, but after some time (6h-1d) the following error occurs when trying to create a new session and store it in redis:

Call to a member function write() on null
#0 [internal function]: Amp\Redis\RespSocket->Amp\Redis\{closure}()  
#1 /usr/share/app/vendor/amphp/amp/lib/Coroutine.php(67): Generator->current()  
#2 /usr/share/app/vendor/amphp/amp/lib/functions.php(96): Amp\Coroutine->__construct()
#3 /usr/share/app/vendor/amphp/redis/src/RespSocket.php(70): Amp\call()  
#4 /usr/share/app/vendor/amphp/redis/src/RemoteExecutor.php(74): Amp\Redis\RespSocket->write()  
#5 [internal function]: Amp\Redis\RemoteExecutor->Amp\Redis\{closure}()  
#6 /usr/share/app/vendor/amphp/amp/lib/Coroutine.php(67): Generator->current()  
#7 /usr/share/app/vendor/amphp/amp/lib/functions.php(96): Amp\Coroutine->__construct()  
#8 /usr/share/app/vendor/amphp/redis/src/RemoteExecutor.php(80): Amp\call()  
#9 /usr/share/app/vendor/amphp/redis/src/RemoteExecutor.php(55): Amp\Redis\RemoteExecutor->enqueue()  
#10 [internal function]: Amp\Redis\RemoteExecutor->Amp\Redis\{closure}()  
#11 /usr/share/app/vendor/amphp/amp/lib/Coroutine.php(118): Generator->send()
#12 /usr/share/app/vendor/amphp/amp/lib/Internal/Placeholder.php(46): Amp\Coroutine->Amp\{closure}()
#13 /usr/share/app/vendor/amphp/amp/lib/Coroutine.php(151): Amp\Coroutine->onResolve()
#14 /usr/share/app/vendor/amphp/amp/lib/functions.php(96): Amp\Coroutine->__construct()
#15 /usr/share/app/vendor/amphp/redis/src/RemoteExecutor.php(62): Amp\call()
#16 /usr/share/app/vendor/amphp/redis/src/Redis.php(1101): Amp\Redis\RemoteExecutor->execute()
#17 [internal function]: Amp\Redis\Redis->Amp\Redis\{closure}()
#18 /usr/share/app/vendor/amphp/amp/lib/Coroutine.php(67): Generator->current()
#19 /usr/share/app/vendor/amphp/amp/lib/functions.php(96): Amp\Coroutine->__construct()
#20 /usr/share/app/vendor/amphp/redis/src/Redis.php(1110): Amp\call()
#21 /usr/share/app/vendor/amphp/redis/src/Mutex/Mutex.php(170): Amp\Redis\Redis->eval()
#22 [internal function]: Amp\Redis\Mutex\Mutex->Amp\Redis\Mutex\{closure}()
#23 /usr/share/app/vendor/amphp/amp/lib/Coroutine.php(67): Generator->current()
#24 /usr/share/app/vendor/amphp/amp/lib/functions.php(96): Amp\Coroutine->__construct()
#25 /usr/share/app/vendor/amphp/redis/src/Mutex/Mutex.php(199): Amp\call()
#26 /usr/share/app/vendor/amphp/http-server-session/src/Session.php(147): Amp\Redis\Mutex\Mutex->acquire()
#27 [internal function]: Amp\Http\Server\Session\Session->Amp\Http\Server\Session\{closure}()
#28 /usr/share/app/vendor/amphp/amp/lib/Coroutine.php(67): Generator->current()
#29 /usr/share/app/vendor/amphp/amp/lib/functions.php(96): Amp\Coroutine->__construct()
#30 /usr/share/app/vendor/amphp/http-server-session/src/Session.php(328): Amp\call()
#31 [internal function]: Amp\Http\Server\Session\Session->Amp\Http\Server\Session\{closure}()
#32 /usr/share/app/vendor/amphp/amp/lib/Coroutine.php(118): Generator->send()
#33 /usr/share/app/vendor/amphp/amp/lib/Success.php(41): Amp\Coroutine->Amp\{closure}()
#34 /usr/share/app/vendor/amphp/amp/lib/Coroutine.php(151): Amp\Success->onResolve()
#35 /usr/share/app/vendor/amphp/amp/lib/functions.php(96): Amp\Coroutine->__construct()
#36 /usr/share/app/vendor/amphp/http-server-session/src/Session.php(329): Amp\call()
#37 /usr/share/app/vendor/amphp/http-server-session/src/Session.php(163): Amp\Http\Server\Session\Session->synchronized()
#38 OWN_CLASS_FOR_SESSION_OPENING(48): Amp\Http\Server\Session\Session->open()

Here is our setup for the session driver:

$sessionSerializer = new CompressingSerializeSerializer();
$host = 'someHost';
$port = 6379;
$pass = 'somePassword';

$redisConfig = Config::fromUri('redis://' . $host . ':' . $port);
if ($pass) {
	$redisConfig = $redisConfig->withPassword($pass);
}

$remoteExecutorFactory = new RemoteExecutorFactory($redisConfig);
$redisSessionStorage = new RedisStorage($remoteExecutorFactory, $sessionSerializer, $sessionConfig->getTtlSeconds());
$sessionStorage = $redisSessionStorage;
$keyedMutex = new Mutex($remoteExecutorFactory);
$idGenerator = new DefaultIdGenerator();
$sessionDriver = new Driver($keyedMutex, $sessionStorage, $idGenerator);

Until now i could not find a setup to manually force this error.
Thank you in advance!

[Niklas Keller]

This might happen if the connection gets closed.

[Max Wagner]

What would be the best way to keep the connection alive over time? Using a loop to recreate the driver every few minutes / hours?

[Niklas Keller]

@maxwagner-dev It should reconnect automatically. If you see this failure it fails permanently I guess?

[Max Wagner]

@kelunik Yes, this error occurred multiple times / one time a day over the last 14 days of testing.

[Niklas Keller]

Please try it again with https://github.com/amphp/redis/releases/tag/v1.0.4.

[Max Wagner]

@kelunik I have implemented your latest release. It's running without any error over the last two days.

You can close the issue.
Thank you very much for the fast solution.

[Niklas Keller]

@maxwagner-dev Thanks for confirming it works as expected now. If you'd like to support our work, you can sponsor us, especially if you're using Amp commercially. :-)