Bug #75710 [Opn]: single-char vars get lost

Edit report at https://bugs.php.net/bug.php?id=75710&edit=1 ID: 75710 Updated by: nikic@php.net Reported by: benjamin dot roth at jaumo dot com Summary: single-char vars get lost Status: Open Type: Bug Package: Scripting Engine problem Operating System: Ubuntu PHP Version: 7.1.12 Block user comment: N Private report: N New Comment: How often are you seeing this issue? Which extensions are you using? In particular interested in anything using shared memory, such as opcache and apcu. Previous Comments: ------------------------------------------------------------------------ [2018-04-26 12:07:21] benjamin dot zikarsky at jaumo dot com We triggered this bug again today. Now on PHP 7.2.4. Many long-running processes (to be more specific: Gearman worker running an Amp-loop) started throwing exceptions: "Undefined variable: m" in this source-file: https://github.com/aws/aws-sdk-php/blob/master/src/Api/Serializer/RestSerializer.php#L112 This source-file is obviously completely unrelated to Amp or our custom codebase. Also it can be assumed to be rather battletested as it is part of the AWS SDK for PHP. We are reasonable sure that the same process ran through the same function multiple times before the error without throwing the exception. ------------------------------------------------------------------------ [2018-04-08 19:10:52] benjamin dot roth at jaumo dot com If a $var is 'null' one line after its creation. How could that be caused by _any_ userland code? ------------------------------------------------------------------------ [2018-04-07 22:14:34] cmb@php.net > Our observations have been made when serving PHP requests with > amp/aerys. Would it be possible that the strange behavior is caused by amphp/aerys in the first place? ------------------------------------------------------------------------ [2017-12-20 08:18:20] benjamin dot roth at jaumo dot com Description: ------------ 1. I am not 100% if I got the right category for that. 2. I was NOT able to reproduce that intentionally but we obsorved that many, many times in production. 3. This only happens in long-running PHP environments. It does NOT happen with PHPFPM as every request creates a separate PHP runtime. Our observations have been made when serving PHP requests with amp/aerys. 4. It does not happen in EVERY long-running process, but WHEN it happens, the current process is affected until it dies Symptom: Single-char vars are instantly dropped / unset. E.g. ---- $f = new Foo(); $f->bar(); ---- Results in ---- [E_NOTICE] Undefined variable: f ---- and ---- Call to a member function bar() on null ---- This does never happen when using variable names with a couple of chars. I didn't find out the exact limit, but as of now I have only seen single-char-vars in logs. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=75710&edit=1