Hooks sequence problem

Function hooked on pre_get_posts is executed before a function hooked on init action.

I’ve checked WordPress actions sequence and init action is triggered before pre_get_posts, so my logic is functions hooked on init should be executed firstly against functions hooked on pre_get_posts.

I’ve installed a plugin which shows the sequence of executed actions and the init action is executed firstly, which is okay.

I tried to debug it, but unfortunately without success. Here is my debugging flow:
I’ve checked with xdebug breaking points the sequence of actions and functions execution. I set 4 breaking points:

1. do_action( ‘init’ ) at line 353 in wp-settings.php
2. do_action_ref_array( ‘pre_get_posts’, array( &$this ) ) at line 2396 in query.php
3. function A which executes on init
4. function B which executes on pre_get_posts

The result is:

1. do_action( ‘init’ ) is called firstly
2. do_action_ref_array( ‘pre_get_posts’, array( &$this ) ) is called secondly
3. and the strange part is here function B is called before A
4. Function A is called after B

So what can be the reason function B is called before A?

Thank you in advance!