[TYPO3-dev] malformed cached config files

[Helmut Hummel]

Hi Roland,

On 27.10.11 13:25, Roland Hager wrote:
> Hi List,
>
> We recently had some problems with malformed cached config files[1].
> We had
>     - unfinished files which gives us a syntax error
>     - corrupted files with some bytecode in it.

Thanks for bringing up this topic.
I also observe problems with (re-)creating these files.
The scenario you describe also happend (luckily only) once recently in a 
high load cluster environment, similar to the one you described. Since 
this happend only once, we did not dig into it any further, but since 
you also mention suh problems, it's probably worth doing so.


There is a race conditions between the checks if the files are available 
and the place where they are actually required. What I observe 
regularily in the php error log, that requiring the temp_cached files 
fail (failed opening required ...)

In general this process not protected against parallel execution.
So in high load scenarios it may happen, that the cache-files will be 
written more than once at the same time. Hopfully the file system 
locking works properly then...

> Obviously this only happens when the config cache has to be regenerated.
> Sometimes the error occurs although no one cleared the config cache
> manually. So under which conditions the config cache files will be
> regenerated?

As you probably already know now, they're only regenerated when they are 
not found. And they are only deleted, if extensions are installed or the 
extension cache is cleared manually.

Kind regards,
Helmut

-- 
Helmut Hummel
TYPO3 Security Team Leader, TYPO3 v4 Core Team Member

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