Core

Markus Klein wrote:

Steps to reproduce

1. rm -rf typo3temp/*
2. Open BE, Page module
3. Click on some random page in the tree
4. Clear the configuration cache via toolbar icon
5. Click on some page again in the tree

An extdirect exception popups at the bottom of the BE
[...]
(the affected class looks rather random, but it is always the same line 244)

I cannot reproduce this on my system, but saw these warnings on a customer system lately.
While this is very likely a race condition in the file backend, I'm still asking myself how this happens and if the temp file is missing during that operation or if some directory is not present.

Markus Klein wrote:

You can continue at this point to work in BE, but
if you clear the configuration cache again and
quickly click on a page in the tree, the complete BE fails.

If the classes cache is inconsistent, everything breaks currently.
See #55029

Needs to be fixed!

Thanks for your response Helmut.

Without knowing the code right now, do the cache backends use any locking at all?

Important one... just ran into this issue with extensions using type hints in backend hooks pointing e.g. to t3lib_TCEmain and that class alias not being available...

I randomly get some error and warning messages if I want to use the EM.

PHP Warning:  rename(/mypath/typo3temp/Cache/Data/cache_classes/530ce35ad4603.temp,/mypath/typo3temp/Cache/Data/cache_classes/typo3_cms_core_compatibility_loadedextensionsarray) [<a href='function.rename'>function.rename</a>]: No such file or directory in /mypath/typo3/sysext/core/Classes/Cache/Backend/SimpleFileBackend.php on line 244
PHP Warning:  rename(/mypath/typo3temp/Cache/Data/cache_classes/530ce35b64123.temp,/mypath/typo3temp/Cache/Data/cache_classes/clearcachemenu) [<a href='function.rename'>function.rename</a>]: No such file or directory in /mypath/typo3/sysext/core/Classes/Cache/Backend/SimpleFileBackend.php on line 244
PHP Warning:  rename(/mypath/typo3temp/Cache/Data/cache_classes/530ce35b68f43.temp,/mypath/typo3temp/Cache/Data/cache_classes/typo3_cms_backend_toolbar_livesearchtoolbaritem) [<a href='function.rename'>function.rename</a>]: No such file or directory in /mypath/typo3/sysext/core/Classes/Cache/Backend/SimpleFileBackend.php on line 244
PHP Fatal error:  Class 'TYPO3\CMS\Backend\Sprite\AbstractSpriteHandler' not found in /mypath/typo3/sysext/backend/Classes/Sprite/SimpleSpriteHandler.php on line 40
PHP Fatal error:  Class 'TYPO3\CMS\Core\Resource\Driver\AbstractDriver' not found in /mypath/typo3/sysext/core/Classes/Resource/Driver/AbstractHierarchicalFilesystemDriver.php on line 35
PHP Fatal error: Class 'TYPO3\CMS\Core\Resource\ResourceStorage' not found in /mypath/typo3temp/Cache/Code/cache_core/ext_localconf_ff0939e805d9053eba290499baf8d6edbd4fb258.php on line 38

Please see the blueprint for solving this: http://wiki.typo3.org/Blueprints/LockingForCaches

I have written a bash script to provoke the error

#!/bin/bash

i="0" 
url="http://introductionpackage.dev.dfau/index.php?id=51" 

while true
do
        rm -R typo3temp/Cache
        i=$[$i+1]
        curl -s -o - $url | grep -o "Fatal error:.*</i>" && echo "Request $i failed" &
        i=$[$i+1]
        curl -s -o - $url | grep -o "Fatal error:.*</i>" && echo "Request $i failed" &
        wait
done
wait

Please replace the url variable with one that matches your site. Run this script from the site root. It tests frontend requests but the issue is present there too.