Python - Cachetools LRUCache KeyError
If your application is threaded and you're getting a "KeyError" while using the non-decorator version of cachetool's LRUCache, then you need to put whatever is manipulating the cache object inside of a lock. Also, since LRUCache is modified when values are gotten from it, you will also need to make sure you're locking when you get values from cache too. If you can use the decorator version of LRUCache, that's preferred since it has built-in locking.Here's an example of the error:
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| [2016-08-10 22:36:30 +0000] [1] [ERROR] [blah/blah_user] "my_key" | |
| Traceback (most recent call last): | |
| File "/usr/local/lib/python3.4/site-packages/thriftpy/server.py", line 92, in handle | |
| self.processor.process(iprot, oprot) | |
| File "/usr/local/lib/python3.4/site-packages/thriftpy/thrift.py", line 244, in process | |
| self.handle_exception(e, result) | |
| File "/usr/local/lib/python3.4/site-packages/thriftpy/thrift.py", line 241, in process | |
| result.success = call() | |
| File "/usr/local/lib/python3.4/site-packages/thriftpy/thrift.py", line 205, in call | |
| *(args.__dict__[k] for k in api_args) | |
| File "/opt/service/blah/dispatcher.py", line 932, in get | |
| return blah.to_thrift() | |
| File "/opt/service/blah/model.py", line 383, in to_thrift | |
| profile = self.profile | |
| File "/opt/service/blah/model.py", line 360, in profile | |
| return service_callers.get_profile(TProfileIdentifiers(id=str(self.profile_id))) | |
| File "/opt/service/blah/util.py", line 121, in func_wrapper | |
| return func(*args, **kwargs) | |
| File "/usr/local/lib/python3.4/site-packages/dogpile/cache/region.py", line 1053, in decorate | |
| should_cache_fn) | |
| File "/usr/local/lib/python3.4/site-packages/dogpile/cache/region.py", line 657, in get_or_create | |
| async_creator) as value: | |
| File "/usr/local/lib/python3.4/site-packages/dogpile/core/dogpile.py", line 158, in __enter__ | |
| return self._enter() | |
| File "/usr/local/lib/python3.4/site-packages/dogpile/core/dogpile.py", line 98, in _enter | |
| generated = self._enter_create(createdtime) | |
| File "/usr/local/lib/python3.4/site-packages/dogpile/core/dogpile.py", line 149, in _enter_create | |
| created = self.creator() | |
| File "/usr/local/lib/python3.4/site-packages/dogpile/cache/region.py", line 630, in gen_value | |
| self.backend.set(key, value) | |
| File "/usr/local/lib/python3.4/site-packages/dogpile/cache/backends/memory.py", line 76, in set | |
| self._cache[key] = value | |
| File "/usr/local/lib/python3.4/site-packages/cachetools/lru.py", line 19, in __setitem__ | |
| cache_setitem(self, key, value) | |
| File "/usr/local/lib/python3.4/site-packages/cachetools/cache.py", line 51, in __setitem__ | |
| self.popitem() | |
| File "/usr/local/lib/python3.4/site-packages/cachetools/lru.py", line 33, in popitem | |
| return (key, self.pop(key)) | |
| File "/usr/local/lib/python3.4/site-packages/cachetools/abc.py", line 36, in pop | |
| raise KeyError(key) | |
| KeyError: "my_key" |