Craft plugin controller for batch update users break with empty page
It was a php.ini config problem, I put some parameters values up and the update succeeded in less than 2 minutes and completed my users batch update.

So you just need to update the values below and reload your web server (ie: Apache).  

max_execution_time 120 (instead of initial value 30)  
memory_limit 512M (instead of initial value 128M)