Extracting return value in gevent from a method which returns 2 values

Question

Note: I am getting this error in unit testing. Haven't been able to deploy it to dev/prod. could it be anything to do with app context? how to create one in py.test?

I recently converted a code which was doing multiple io calls to multithreaded. I used gevent to do so. Here is simplified version of the code (removing all necessary identifiable information)

ge_results = {}

if random_condition_is_true():
    ge_results['first_key'] = Greenlet.spawn(another_service.fetch_data, ids, another_id)
    

ge_results['second_key'] = Greenlet.spawn(some_other_method, ids)

if another_condition_is_true():
    ge_results['third_key'] = Greenlet.spawn(third_method_call_which_returns_two_values, ids=ids)

results = gevent.joinall(list(ge_results.values()))

if 'first_key' in ge_results:
    first_key = ge_results['first_key'].value

if 'third_key' in ge_results:
    third_data_set = ge_results['third_key'].value[1]

The issue is happening on third_data_set. The third_method_call_which_returns_two_values method return 2 values, and i am trying to assign second value to third_data_set but i am unable to do so.

When i look into this value using pdb, I see these values

(Pdb) xx = greenlets_result_map['third_key']
(Pdb) xx
<Greenlet at 0x7f3350203a70: third_method_call_which_returns_two_values(AA1(..., qwe=[d,d,d,d], data_i_want=[DataIWant(BB=BB1(...)>

Here it is visible that I receive a Greenlet object which has AA1 object. Which then has data_i_want. But i am unable to get it.

When i do xx.value it says NoneType. If i try xx[1].value, i get error that its not subscriptable

I am not sure how to get this value.

Just to be clear, methods which are returning only one value are working perfectly fine with greenlets_result_map['key'].value code.

Update

An interesting thing that i have noticed that if a method has been called then the greenlet has _run value otherwise method name.

For example, here is the output of ge_results['first_key']

(Pdb) ge_results['first_key']
(Pdb) <Greenlet at 0x7f3350203830: _run>

See there is _run here. But here is the output for ge_results['second_key']

(Pdb) ge_results['second_key']
(Pdb) <Greenlet at 0x7f3350203950: some_other_method([])>

See it doesn't have _run. Am i not joining them all?

Extracting return value in gevent from a method which returns 2 values

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