# Not forking parrallel tasks?

**URL:** <https://forum.ansible.com/t/not-forking-parrallel-tasks/13863>\
**Category:** Ansible Project\
**Tags:** ubuntu\
**Created:** [November 7, 2013, 6:04pm UTC](https://forum.ansible.com/t/not-forking-parrallel-tasks/13863 "2013-11-07T18:04:46Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![Silvio\_Tomatis](https://avatars.discourse-cdn.com/v4/letter/s/5e9695/32.png) [@Silvio\_Tomatis](https://forum.ansible.com/u/Silvio_Tomatis)\
**Post date:** [August 11, 2015, 10:20am UTC](https://forum.ansible.com/t/not-forking-parrallel-tasks/13863/21 "2015-08-11T10:20:41Z")

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Removing the connections as I mentioned in the last message solved the problem only temporarily (and to be honest I don’t know how).  
When the issue resurfaced, I dug a little more and ended up on this thread: [https://groups.google.com/forum/#!msg/ansible-project/8p3XWlo83ho/KlIqch\_UxTEJ](https://groups.google.com/forum/#!msg/ansible-project/8p3XWlo83ho/KlIqch_UxTEJ)

To summarize, I had UserKnownHostsFile /dev/null, so ansible smellt an empty known\_hosts file and run in a serial fashion to allow me to type “yes” atfer each host connection.  
Setting ansible\_host\_key\_checking=0 solved the issue for good for me.

That explains why David’s issue was solved upgrading: ansible 1.3.3 had support for hashed hosts that ansible 1.2.3 hadn’t.  
I really hope the solution proposed in the other thread will be accepted: a warning about the cause of the serial behaviour would have been priceless.

Silvio

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