If you’re simply locking an object, I’d prefer to use synchronized Example: Lock.acquire(); doSomethingNifty(); // Throws a NPE! Lock.release(); // Oh noes, we never release the lock! You have to explicitly do try{} finally{} everywhere. Whereas with synchronized, it’s super clear and impossible to get wrong: synchronized(myObject) { doSomethingNifty(); } That said, Locks may be … Read more
Here goes my humble attempt to explain the concept to newbies around the world: (a color coded version on my blog too) A lot of people run to a lone phone booth (they don’t have mobile phones) to talk to their loved ones. The first person to catch the door-handle of the booth, is the … Read more
You are specifically asking about how they internally work, so here you are: No synchronization private int counter; public int getNextUniqueIndex() { return counter++; } It basically reads value from memory, increments it and puts back to memory. This works in single thread but nowadays, in the era of multi-core, multi-CPU, multi-level caches it won’t … Read more
First – most classes will never need to be thread-safe. Use YAGNI: only apply thread-safety when you know you actually are going to use it (and test it). For the method-level stuff, there is [MethodImpl]: [MethodImpl(MethodImplOptions.Synchronized)] public void SomeMethod() {/* code */} This can also be used on accessors (properties and events): private int i; … Read more
The Theory In theory, when a thread tries to lock a mutex and it does not succeed, because the mutex is already locked, it will go to sleep, immediately allowing another thread to run. It will continue to sleep until being woken up, which will be the case once the mutex is being unlocked by … Read more
I’ll cover each point separately. Some evil code may steal your lock (very popular this one, also has an “accidentally” variant) I’m more worried about accidentally. What it amounts to is that this use of this is part of your class’ exposed interface, and should be documented. Sometimes the ability of other code to use … Read more
The lock statement is translated by C# 3.0 to the following: var temp = obj; Monitor.Enter(temp); try { // body } finally { Monitor.Exit(temp); } In C# 4.0 this has changed and it is now generated as follows: bool lockWasTaken = false; var temp = obj; try { Monitor.Enter(temp, ref lockWasTaken); // body } finally … Read more