App Engine Python27 SDK - NDB Query.iter() QueryIterator returns "Deadlock waiting for, pending" error

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Since I am using NDB for my projects, on Python 2.7 SDK, I cannot use Query().iter() normally with Jinja2 templates.

My usual code follows this pattern:

mc_key = ...
instances = memcache.get('instances-%s' % mc_key)
if not instances:
    q_i = MyModel.query(...)
    instances = q_i.iter()
    if instances:
        memcache.set('instances-%s' % mc_key, instances)

And then in Jinja2:

{% for i in instances %}
    {{i.property1}}
{% endfor %}

This also happens when I call the QueryIterator object in the Python code. Adding to the previous Python code:

for i in instances:
    # Do something with i

I always get a "deadlock waiting for " when I loop the iterator.

A working walkaround is:

q_i = MyModel.query()
instances = q_i.iter()
if instances:
    instances = list(instances)

Someone knows why that next() does not work as I expected? Some more elegant and/or efficient solution? Thank you in advance.

asked 1 min ago

Indavelopers

1