results get stored to a tempfile. it has been recently fixed. Huge "prints" 
are still a problem and are discouraged, but now you can have a result as 
big as you wish.

On Thursday, May 12, 2016 at 5:19:04 AM UTC+2, Andre Kozaczka wrote:
>
> I'm curious what workarounds folks have come up with regarding this issue. 
>
> On Monday, February 29, 2016 at 1:41:41 PM UTC-5, Boris Aramis Aguilar 
> Rodríguez wrote:
>>
>> Hi, there is an issue driving me crazy with the web2py scheduler:
>>
>> If you return something that has a huge size then it will always timeout; 
>> even if the scheduler task correctly finishes. Let me explain with an 
>> example:
>>
>> def small_test():
>>     s = 's'*1256018
>>     another_s = s
>>     #print s
>>     #print another_s
>>     #print 'FINISHED PROCESS'
>>     return dict(s = s, another_s = another_s, f = 'finished')
>>
>> small_test is the function to execute, as you can see a string full of 
>> 's' 1256018 times is. Simple
>>
>> So when you enqueue the scheduler every time the output is the same: 
>> http://prnt.sc/a9iarj (screenshot of the TIMEOUT)
>>
>> As you can see from the screenshot, the process actually finished; while 
>> logging the scheduler output shows the following:
>>
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:   work to do 1405
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:    new scheduler_run 
>> record
>> INFO:web2py.scheduler.PRTALONENETLAPP-SRV#24475:new task 1405 
>> "small_test" portal/default.small_test
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475: new task allocated: 
>> portal/default.small_test
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:   task starting
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:    task started
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:    new task report: 
>> COMPLETED
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:   result: {"s": 
>> "ssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss$
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:    freeing workers 
>> that have not sent heartbeat
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:    freeing workers 
>> that have not sent heartbeat
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:    freeing workers 
>> that have not sent heartbeat
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:........recording 
>> heartbeat (RUNNING)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:    task timeout
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475: recording task report 
>> in db (TIMEOUT)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475: status TIMEOUT, 
>> stop_time 2016-02-29 11:56:52.393706, run_result {"s": 
>> "sssssssssssssssssssssssssss$
>> INFO:web2py.scheduler.PRTALONENETLAPP-SRV#24475:task completed (TIMEOUT)
>> DEBUG:web2py.scheduler.PRTALONENETLAPP-SRV#24475:looping...
>> INFO:web2py.scheduler.PRTALONENETLAPP-SRV#24475:nothing to do
>>
>>
>>
>> As you can see there is a TaskReport object in the queue with a COMPLETED 
>> status (I know this because I read the scheduler.py code of web2py) So I'm 
>> pretty sure the task finishes quite fast but then it hangs.
>>
>> So I did another test, that doesn't directly use the scheduler but only 
>> calls the executor method from the scheduler and usess process; just like 
>> the scheduler would:
>>
>> from gluon.scheduler import Task
>> from gluon.scheduler import executor
>> t = Task(app='portal', function='small_test', timeout = 120)
>> import logging
>> logging.getLogger().setLevel(logging.DEBUG)
>> import multiprocessing
>> queue = multiprocessing.Queue(maxsize = 1)
>> out = multiprocessing.Queue()
>> t.task_id = 123
>> t.uuid = 'asdfasdf'
>> p = multiprocessing.Process(target=executor, args=(queue, t, out))
>> p.start()
>> p.join(timeout = 120)
>> p.is_alive()
>>
>>
>> when the join finishes waiting (2 minutes) if you check for p.is_alive() 
>> it always returns True; but when you do a queue.get() and then instantly 
>> check for p.is_alive() the process finishes!!!!! 
>>
>> So i noticed the problem is from multiprocessing library, due to the fact 
>> that it can't handle lots of data from a queue (which seems kind of strange 
>> for my case, but I don't know how it is implemented); anyways i found this 
>> bug: http://bugs.python.org/issue8237 and 
>> http://bugs.python.org/issue8426
>>
>> The interesting part is it is actually documented (I didn't knew that):
>>
>> https://docs.python.org/2/library/multiprocessing.html#multiprocessing-programming
>>
>> But in my current implementation this will happen quite often, I'll work 
>> on a work-around but I would really like that web2py scheduler could handle 
>> large data output from my processes for me, but well that is my wish and I 
>> would like to have some guidance on this issue and avoid a work-around.
>>
>> Anyway, this should be documented somewhere in web2py too (that probably 
>> could had saved me a week of code reading and debugging); or it should be 
>> managed somehow (I wouldn't naturally expect an output limit besides the 
>> database implementation).
>>
>

-- 
Resources:
- http://web2py.com
- http://web2py.com/book (Documentation)
- http://github.com/web2py/web2py (Source code)
- https://code.google.com/p/web2py/issues/list (Report Issues)
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