Re: [Fab-user] How to use parallel execution via API

[Jeff Forcier]

On Sun, Jul 15, 2012 at 4:02 PM, Mohamed Lrhazi <address@hidden> wrote:
> Thanks Jeff.
>
> If I enable parallel execution, would my disconnect_all() interrupt
> all dispatched ssh sessions, or just the one in my iteration?

I haven't tested this but I believe the answer is "yes, the latter",
assuming you're calling disconnect_all() inside your task function.

When execute()* runs a task in parallel, it creates a new subprocess
for each host, and that process gets its own distinct copy of Fabric's
global module state. (In fact, that copy of the cache is emptied
before the subprocess run, so that no external connections end up
shared between parent & children.)

* Forgot to make this explicit before, but you *must* use the
execute() function for parallelism to work, simply setting
env.parallel and then calling eg run("foo") will not do what you want.
Have to put run() statements inside a function and hand that function
to execute().

-Jeff

> On Sun, Jul 15, 2012 at 6:42 PM, Jeff Forcier <address@hidden> wrote:
>> On Sun, Jul 15, 2012 at 3:31 PM, Mohamed Lrhazi <address@hidden> wrote:
>>> Is this possible? I went through the docs and it does not show any
>>> examples of such usage, only via command line or a decorator.
>>
>> It could be more explicit, but it's in there if you read carefully :)
>>
>>     http://docs.fabfile.org/en/1.4.3/usage/parallel.html#command-line-flags
>>
>>     "One may also force all tasks to run in parallel by using the
>> command-line flag -P or the env variable env.parallel."
>>
>> So you can tickle env.parallel directly or via 'with settings', and
>> then task executions via execute() will run in parallel. E.g.:
>>
>>     with settings(parallel=True):
>>         execute(mytaskfunction, hosts=[...])
>>
>> In addition, decorators are simply functions themselves and can be
>> used to temporarily wrap otherwise un-decorated functions, so you
>> could also:
>>
>>     execute(parallel(mytaskfunction), hosts=[...])
>>
>> Hope that helps,
>> Jeff
>>
>>>
>>> Is there a way?
>>>
>>> Thanks a lot,
>>> Mohamed.
>>>
>>> _______________________________________________
>>> Fab-user mailing list
>>> address@hidden
>>> https://lists.nongnu.org/mailman/listinfo/fab-user
>>
>>
>>
>> --
>> Jeff Forcier
>> Unix sysadmin; Python/Ruby engineer
>> http://bitprophet.org



-- 
Jeff Forcier
Unix sysadmin; Python/Ruby engineer
http://bitprophet.org