TYPO3 Core

Because of problems with PHP on IIS and PHP-Sessions the exec() function, that runs convert/combine crashes the IIS and cmd.exe and convert.exe gonna hang in the process list of Windows.
So nobody can use imagemagick for thumbnails, image manipulation etc after crashing.

The problem with PHP, IIS and Sessions is, that PHP can't correctly run an external command when having an open session. This is true for all php 4 + 5 versions.

The solution for this is to close the Session before executing the exec function.
Session_Write_Close();
exec....
Session_Start();

I came to the solution while reading this forum-thread:
http://kuerzer.de/ghNGsvMhx

I suggest to make an option in the installtool for this problem, especially for IIS users.

Occures in:
t3lib/class.t3lib_diff.php
t3lib/class.t3lib_iconworks.php
t3lib/class.t3lib_stdgraphic.php
t3lib/thumbs.php

at every exec() function that executes convert/combine
(issue imported from #M3731)