Caution

[valq7711]

Сaution

Only variable itself is thread safe, not its content:
if there is self.x = dict(a ='foo') in one thread and self.x['a'] = 'bar' in another one (without preliminary reinitialization self.x with fresh dict), self.x['a'] will be changed everywhere, even in iceblock, since the latter is a shallow copy.