You have 1 worker process. One ansible-playbook process is the control
process, the other is the worker.
On Thu, Jun 11, 2020 at 9:43 AM Jagadeeshkumar Dittakavi <
d.jagadeeshku...@gmail.com> wrote:
> Thank you Matt!
> In the above example I have explicitly passed --forks=1 but still there
> are 2 worker processes(PIDs 69484 and 69520) were spawned, that means
> there will be minimum 2 workers get spawned and we can't limit that to one?
> I understand that there is no control to limit the total number of
> processes will be spawned by the workers.
>
> On Thursday, June 11, 2020 at 7:54:01 PM UTC+5:30, Matt Martz wrote:
>>
>> There are a number of steps involved here.
>>
>> 1. The primary playbook process spawns a worker
>> 2. The worker executes the async_wrapper for the command module
>> 3. The async_wrapper forks to daemonize
>> 4. The async_wrapper executes the transferred module
>> 5. The actual module is contained within what we call AnsiballZ which is
>> a compressed archive, and it extracts and executes the actual python code
>> 6. Actual module executing.
>>
>> `forks` only limits how many workers can be launched by the primary
>> playbook process, not how many processes will be spawned as a result of the
>> worker.
>>
>> On Thu, Jun 11, 2020 at 7:01 AM Jagadeeshkumar Dittakavi <
>> d.jagad...@gmail.com> wrote:
>>
>>> @Matt,
>>>
>>> Got another question in concurrency support in Ansible.
>>> Is there any way to limit the number of processes that could be spawned
>>> on a given host?
>>> My requirement is not to execute the commands/scripts remotely. In my
>>> case, the whole play needs to be executed on locahost only.
>>> I have tried a simple test program and noticed that there are as many as
>>> 6 processes are spawned to execute 'sleep 20' asynchronously.
>>>
>>> Please kindly revert. Thank you inadvance.
>>>
>>> *Command:* ansible-playbook test_playbook.yml --forks=1
>>>
>>>
>>>
>>> *Processes:*
>>>
>>> root 69484 34309 9 04:50 pts/10 00:00:00 /usr/bin/python2
>>> /usr/bin/*ansible*-playbook test_playbook.yml --forks=1
>>>
>>> root 69509 1 0 04:50 ? 00:00:00 /usr/bin/python2
>>> /root/.*ansible*/tmp/*ansible*-tmp-1591876209.82-38354017880191/async_wrapper.py
>>> 198806654079 50
>>> /root/.*ansible*/tmp/*ansible*-tmp-1591876209.82-38354017880191/command.py
>>> _
>>>
>>> root 69510 69509 0 04:50 ? 00:00:00 /usr/bin/python2
>>> /root/.*ansible*/tmp/*ansible*-tmp-1591876209.82-38354017880191/async_wrapper.py
>>> 198806654079 50
>>> /root/.*ansible*/tmp/*ansible*-tmp-1591876209.82-38354017880191/command.py
>>> _
>>>
>>> root 69511 69510 0 04:50 ? 00:00:00 /usr/bin/python2
>>> /root/.*ansible*/tmp/*ansible*
>>> -tmp-1591876209.82-38354017880191/command.py
>>>
>>> root 69512 69511 1 04:50 ? 00:00:00 /usr/bin/python2 /tmp/
>>> *ansible*_f9ckPD/*ansible*_module_command.py
>>>
>>> root 69520 69484 3 04:50 pts/10 00:00:00 /usr/bin/python2
>>> /usr/bin/*ansible*-playbook test_playbook.yml --forks=1
>>>
>>>
>>>
>>>
>>>
>>> *Code:*
>>>
>>> [root@oracle-siha file_copy_test]# cat test_playbook.yml
>>>
>>> - name: Testing processes
>>>
>>> gather_facts: no
>>>
>>> hosts: localhost
>>>
>>> tasks:
>>>
>>> - name: run sleep command
>>>
>>> async: 50
>>>
>>> poll: 0
>>>
>>> command: sleep 20
>>>
>>> register: res
>>>
>>> - name: wait for the completion
>>>
>>> async_status:
>>>
>>> jid: "{{ res.ansible_job_id }}"
>>>
>>> register: output
>>>
>>> until: output.finished
>>>
>>> delay: 5
>>>
>>> retries: 10
>>>
>>>
>>>
>>> On Friday, June 5, 2020 at 9:50:19 AM UTC+5:30, Jagadeeshkumar Dittakavi
>>> wrote:
>>>>
>>>> Thank you Matt for the detailed and quick reply.. Much appreciated the
>>>> support from the community.
>>>>
>>>> On Friday, June 5, 2020 at 12:29:30 AM UTC+5:30, Matt Martz wrote:
>>>>>
>>>>> Yes, it would utilize the threading library in Python. The GIL is a
>>>>> primary cause to the CPU restrictions. Our main process that orchestrates
>>>>> all of the task executions is already heavily CPU bound, so adding
>>>>> additional threads to the same core can cause a decrease in performance.
>>>>> Assuming we create a process model plugin type, other process models are
>>>>> possible, such as using asyncio, concurrent.futures, gevent, etc. But I
>>>>> don't expect this work to be complete any time soon.
>>>>>
>>>>> So for now, consider forking the only process model for the near
>>>>> future.
>>>>>
>>>>> On Thu, Jun 4, 2020 at 1:51 PM Jagadeeshkumar Dittakavi <
>>>>> d.jagad...@gmail.com> wrote:
>>>>>
>>>>>> Thank you for the prompt reply.. Just a curious question: Is the
>>>>>> threading work that is underway based on python threads or pthreads or
>>>>>> any
>>>>>> other threading mechanism? As you mentioned that the threading model is
>>>>>> not
>>>>>> going to be performant, was the reason being the python's GIL?
>>>>>>
>>>>>>
>>>>>> On Friday, June 5, 2020 at 12:01:14 AM UTC+5:30, Matt Martz wrote:
>>>>>>>
>>>>>>> The only current process model is forking. There has been some work
>>>>>>> done to add a threaded process model, but there are some large hurdles
>>>>>>> to
>>>>>>> overcome.
>>>>>>>
>>>>>>> In practice, it is not necessarily more performant, and in many
>>>>>>> cases it was less performant, as it causes more CPU contention on a
>>>>>>> single
>>>>>>> core that is already resource constrained.
>>>>>>>
>>>>>>> On Thu, Jun 4, 2020 at 1:18 PM Jagadeeshkumar Dittakavi <
>>>>>>> d.jagad...@gmail.com> wrote:
>>>>>>>
>>>>>>>> I am a newbie to ansible but I got to explore how to run a tasks in
>>>>>>>> parallel by spawing a thread for each task instead of a process. My
>>>>>>>> requirement is to run the playbook on my localhost and there is no
>>>>>>>> remote
>>>>>>>> task execution needed.
>>>>>>>> I also would like to wait for all threads to complete before I move
>>>>>>>> on to a task that has to be serialised.
>>>>>>>>
>>>>>>>> Can I chose thread vs process when it comes to parallel task
>>>>>>>> execution?
>>>>>>>> If it is possible to spawn threads from ansible, are they
>>>>>>>> equivalent to python greenthreads or pthreads or something else?
>>>>>>>>
>>>>>>>> Thank you in advance!
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> You received this message because you are subscribed to the Google
>>>>>>>> Groups "Ansible Project" group.
>>>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>>>> send an email to ansible...@googlegroups.com.
>>>>>>>> To view this discussion on the web visit
>>>>>>>> https://groups.google.com/d/msgid/ansible-project/0d59cf96-b053-4390-8dbb-663c70403104o%40googlegroups.com
>>>>>>>> <https://groups.google.com/d/msgid/ansible-project/0d59cf96-b053-4390-8dbb-663c70403104o%40googlegroups.com?utm_medium=email&utm_source=footer>
>>>>>>>> .
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Matt Martz
>>>>>>> @sivel
>>>>>>> sivel.net
>>>>>>>
>>>>>> --
>>>>>> You received this message because you are subscribed to the Google
>>>>>> Groups "Ansible Project" group.
>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>> send an email to ansible...@googlegroups.com.
>>>>>> To view this discussion on the web visit
>>>>>> https://groups.google.com/d/msgid/ansible-project/48f0ed5f-83c7-4bf4-a991-94ec78ce832eo%40googlegroups.com
>>>>>> <https://groups.google.com/d/msgid/ansible-project/48f0ed5f-83c7-4bf4-a991-94ec78ce832eo%40googlegroups.com?utm_medium=email&utm_source=footer>
>>>>>> .
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Matt Martz
>>>>> @sivel
>>>>> sivel.net
>>>>>
>>>> --
>>> You received this message because you are subscribed to the Google
>>> Groups "Ansible Project" group.
>>> To unsubscribe from this group and stop receiving emails from it, send
>>> an email to ansible...@googlegroups.com.
>>> To view this discussion on the web visit
>>> https://groups.google.com/d/msgid/ansible-project/f0093a03-d20b-4187-8bca-913e10770f5fo%40googlegroups.com
>>> <https://groups.google.com/d/msgid/ansible-project/f0093a03-d20b-4187-8bca-913e10770f5fo%40googlegroups.com?utm_medium=email&utm_source=footer>
>>> .
>>>
>>
>>
>> --
>> Matt Martz
>> @sivel
>> sivel.net
>>
> --
> You received this message because you are subscribed to the Google Groups
> "Ansible Project" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to ansible-project+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/ansible-project/e87deb71-f620-461f-ac30-2c61931d8a51o%40googlegroups.com
> <https://groups.google.com/d/msgid/ansible-project/e87deb71-f620-461f-ac30-2c61931d8a51o%40googlegroups.com?utm_medium=email&utm_source=footer>
> .
>
--
Matt Martz
@sivel
sivel.net
--
You received this message because you are subscribed to the Google Groups
"Ansible Project" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to ansible-project+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/ansible-project/CAD8N0v8L-y%2BNhAO0G0jjQOeXrD%3DfSBTc%2BUUrmJ9MybdPR1jZGw%40mail.gmail.com.
