Ask Your Question

Mistral IndexError in line 290

asked 2016-01-21 19:28:14 -0500

michael@plexxi gravatar image

I'm running mistral version 0.1.2 on a workflow that does both fork/join and with-item multiple executions. Mistral is failing with the following: File "/opt/mistral/virtualenv/lib/python2.7/site-packages/mistral/workflow/", line 290, in _triggers_join in_t_ex = in_t_execs[-1] IndexError: list index out of range

Looking at that code I'm seeing the following comments:

# TODO(rakhmerov): Method signature is incorrect given that
# we may have multiple task executions for a task. It should
# accept inbound task execution rather than a spec.
def _triggers_join(self, join_task_spec, inbound_task_spec):


# TODO(rakhmerov): Temporary hack. See the previous comment.
      in_t_ex = in_t_execs[-1]

Is there a known bug or deficiency here?

Thanks! - Michael

edit retag flag offensive close merge delete

1 answer

Sort by ยป oldest newest most voted

answered 2016-07-17 07:35:18 -0500

michal-gershenzon gravatar image

Adding this answer in case someones reads this in the future.

This issue is solved on master(Newton) : (

It is also possible to fix it with one line in Liberty: On the Mistral VM in file: /usr/lib/python2.7/site-packages/mistral/workflow/

Change Line 284 from:

       in_t_ex = in_t_execs[-1]

To this:

       in_t_ex = in_t_execs[-1] if in_t_execs else None
edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Get to know Ask OpenStack

Resources for moderators

Question Tools

1 follower


Asked: 2016-01-20 19:41:06 -0500

Seen: 66 times

Last updated: Jul 17 '16