c# - Multi-threaded application crash - possible memory corruption? -

i have multi-threaded application in c# uses lock() access dictionary. there 2 threads, consumer , producer. locking mecanism simple. application runs under heavy load weeks without problem.

today crashed. digged windbg see exception , keynotfound when accessing dictionary.

what problems cause crash? should consider memory corruption may occur or not?

making locking fined-grained cause this. example:

    bool haskey(string key) {         lock (_locker) {             return _dictionary.containskey(key);         }     }     int getvalue(string key) {         lock (_locker) {             return _dictionary[key];         }     } 

and using this:

    void kaboom() {         if (haskey("foo")) {             int value = getvalue("foo");             // etc..         }     } 

that won't work, dictionary change between haskey , getvalue call. entire operation needs locked. , yes, goes wrong once month or so.

    bool trygetvalue(string key, out int value) {         lock (_locker) {             if (!haskey(key)) return false;             value = getvalue(key);             return true;         }     }