3 ms·
Every Python object has a backing dictionary, so if any object has to be shared between threads in a threadsafe fashion, then dictionaries need to be threadsafe
by koenigdavidmj 15y ago
Every Python object has a backing dictionary, so if any object has to be shared between threads in a threadsafe fashion, then dictionaries need to be threadsafe.
- justinsb 15y agoRight. I think that backing dictionary could probably be replaced with a more thread-friendly implementation, even if we have to offer reduced guarantees.
- swolchok 15y agoOr every Python object's backing dictionary needs to use the special threadsafe implementation.
- raymondh 15y agoThis is tricky because dictionaries need to call __hash__ which can run arbitrary Python code, so it's non-trivial to make the dictionary threadsafe.
- kingkilr 15y ago__eq__ as well
- dfox 15y agoIt's perfectly possible and even reasonable to call __hash__ before acquiring lock on the dictionary (and cache keys' hashes for data in the dictionary). On the other hand, when almost every object is backed by dictionary, the locking has to be very fast, which seems to me like almost unsolvable problem.
- lobster_johnson 15y agoJust make __hash__() wrap the underlying dict in a thread-safe one that delegates the calls.
- lobster_johnson 15y agoThat's an argument for revamping the backing dictionary, really. If __hash__() is a problem, make it return a thread-safe proxy that delegates to the object's dictionary.