![]() ![]() It’s suggested to use a private readonly static object to lock. A reference to a waiting-queue, which contains the threads that are waiting for notification of a change in the state of the lock-object.A reference to a ready-queue, which contains the threads that are ready to obtain the lock. ![]() A reference to the thread that currently holds the lock (through the specific lock-object).So, one specific lock needs to use a specific object, and if two separate locks are needed, two separate objects need to be used Monitor.Enter() acquires an exclusive lock based on the lock-object, and Monitor.Exit() releases the lock. The Monitor based locks are uniquely identified with an object. NET specific class used for exclusive locks. Use the other synchronization constructs for specific needs, for example, when you want to allow a specific number (more than one) of threads to access a critical section of code. It’s almost always advised to use lock() over other synchronization constructs, as chances of writing error-prone multi-threaded code is much less. The compiler translates the lock statement into a Monitor.Enter() and Monitor.Exit() pair. NET, the lock() is constructed with Monitor class internally. It can lock a section of code that needs to be handled in thread-safe way. The lock() keyword is the most widely used construct for thread synchronization. Let's now dive into some code in C# and see examples of some the above-mentioned synchronization constructs. ConcurrentDictionary: thread-safe collection of key-value pairs.ConcurrentStack: thread-safe LIFO collection.ConcurrentQueue: thread-safe FIFO collection.ConcurrentBag: thread-safe collection of unordered items.Some of the very useful thread-safe collections are That means, they can be read or be written safely even when multiple threads are accessing them concurrently. The last synchronization technique we have are the thread safe or concurrent collections.NET Framework 4.0 introduced a new bunch of collections under the namespace, that are thread-safe by nature. The volatile keyword, Thread.VolatileRead, Thread.VolatileWrite. ![]() There are three types of nonblocking synchronization constructs: ![]() By using this particular technique, we are able to protect access to a common field with specific access rules. Monitor.Wait(), Monitor.Pulse(), Monitor.PulseAll()Īnother synchronization technique we have is called nonblocking synchronization.Event wait handles ( ManualResetEvent, AutoResetEvent, CountdownEvent).Thread interaction (or thread signaling) means that a thread can pause and wait until a notification is received from another thread. ReaderWriterLock / ReaderWriterLockSlimĪpart from locks, we also have the notion of Signaling Constructs for synchronization.There are also two different types of nonexclusive locks available: Nonexclusive locks, on the other hand, allow a limited number of threads to access a single resource or piece of code at the same time. lock(), Monitor.Enter() - Monitor.Exit(): Actually lock is just syntactic sugar of the Monitor.Enter - Monitor.Exit construct in C#.There are two different types of exclusive locks available: Until the thread finishes executing that code, no other thread will be able to enter (e.g. There are two types of locks: exclusive and nonexclusive.Įxclusive locks only allow one thread to access a certain piece of code exclusively. So, only one thread (person) can enter the block of code (room) protected with a lock at any given point in time. The next person needs to wait until the previous person comes out and gives back the key. Locks create something like a room with a lock, for which only one key is there and only the person with the key can enter. Using locks we can lock a section of code that needs to be handled in a thread-safe way, or commonly known as a “critical section” of code. A lock limits the number of threads that can perform any kind of activity on a certain piece of code. In today's Part 4 of this small series on Threading, Tasks, Async Code and Synchronization Techniques we are going to explore details on the various synchronization techniques supported for protecting access on a sensitive block of code between multiple threads and see some examples of the constructs we use in C#.Īs we saw in the previous article, the first and most important technique we have is the use of the lock keyword. ![]()
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