For most of the Drush commands it is not too difficult to get XDebug and Drush working togethr and catch staff in your IDE, e.g. PhpStorm.
However, I ran into a deadlock when Drush is calling itself for a sub-process. This happens e.g. if you execute
drush @site updatedb because this will invoke a second PHP task for the cache-clear all command. This second PHP task wants to connect to the Xdebug port as well which is still in use by the parent PHP task. This results in a deadlock: the child is waiting for the XDebug port to become available and the parent task is waiting for the child task - for ever or until Ctrl-C.
Is there a way around this?