![]() getInstace() method first check for whether the instance is null and then initialized the instance and return to the caller. #Deadlock in java how toThis is also a popular multi-threading interview question during core java interviews. In this article, we will see how to find race condition in Java and two sample code patterns which often causes race conditions in Java.Īnd, if you are serious about learning Multithreading in Java then you can also check out these advanced Mulitthreaidng and concurrency courses to become an expert in Multithreading, concurrency, and Parallel programming in Java with a strong emphasis on high performance.Ī classical example of the "check and act" race condition in Java is the getInsta n ce() method of Singleton Class, remember that was one question which we have discussed on 10 Interview questions on Singleton pattern in Java as " How to write thread-safe Singleton in Java ". atomic operations are not subject to race conditions because those operations cannot be interleaved. #Deadlock in java updateIf two threads try to increment count at the same time and if they read the same value because of interleaving of a read operation of one thread to update operation of another thread, one count will be lost when one thread overwrite increment done by another thread. The C lassical example of the Race condition is incrementing a counter since increment is not an atomic operation and can be further divided into three steps like reading, update, and write. Race conditions occur when two threads operate on the same object without proper synchronization and their operation interleaves on each other. Anyway, Race conditions are just o n e of the hazards or risks presented by the use of multi- threading in Java just like deadlock in Java. So whenever a thread needs to access the object, it has to first acquire the lock or monitor of its object, work on the object and then release the lock.Race condition in Java is a type of concurrency bug or issue that is introduced in your program because of parallel execution of your program by multiple threads at the same time, Since Java is a multi-threaded programming language hence the risk of Race condition is higher in Java which demands a clear understanding of what causes a race condition and how to avoid that. The monitor or lock is an internal entity and is associated with every object. We have already mentioned that we use monitors or locks to implement synchronization. As a programmer, we should review the code thoroughly to check for potential race conditions that might occur. The best way to detect race condition is by code review. When we properly synchronize the threads such that at a time only one thread will access the resource, and the race condition ceases to exist. Race conditions occur due to a lack of proper synchronization of threads in the program. The problem arises when multiple threads access the same resource at the same time. One thing to consider is that there is no problem if multiple threads are trying to access a shared resource only for reading. In a multithreaded environment, when more than one thread tries to access a shared resource for writing simultaneously, then multiple threads race each other to finish accessing the resource. Now, let us discuss some basic concepts related to synchronization in Java. Going forward, we will discuss synchronization in Java in detail in this tutorial. When a monitor is being accessed by a particular thread, the monitor is locked and all the other threads trying to enter the monitor are suspended until the accessing thread finishes and releases the lock. When a thread gets the lock, then, we can say the thread has entered the monitor. A monitor can be accessed by only one thread at a time. We use a concept called Monitors to implement synchronization. ![]() To avoid these errors we need to go for synchronization of shared resources so that the access to these resources is mutually exclusive. Most of the time, concurrent access to shared resources in Java may introduce errors like “Memory inconsistency” and “thread interference”. ![]() In this case, JVM ensures that Java synchronized code is executed by one thread at a time. In this case, we do not need to synchronize the resource. If the resource is immutable, then the threads will only read the resource either concurrently or individually. We need synchronization when the shared object or resource is mutable. We use keywords “synchronized” and “volatile” to achieve Synchronization in Java Multi-threading Without SynchronizationĪs Java is a multi_threaded language, thread synchronization has a lot of importance in Java as multiple threads execute in parallel in an application. ![]()
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