Parallel Poller Run

Hi,
       I want to know that, is there any check in poller.php to avoid 
       parallel poller run. I have seen the code of poller.php the only check 
       I could find was the limit on the time since the last poller run. (60 or 300 sec.) 
       depending on the cron settings. 
       My concern is that if for some reason a poller instance does not finish in (60 or 300 sec.)
       another poller instance would start running after (60 or 300 sec.)
        I would really appriciate if someone can shed light on this issue.

Best Regards
Rizwan
 		 	   		  
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