java concurrency course

Java Concurrency Programming: Concurrenthashmap of Concurrent Containers (reprint)The following part of the content is reproduced from:http://www.haogongju.net/art/2350374New concurrent packages have been added to the JDK5, and concurrent containers have improved concurrency performance through mechanisms relative to the synchronization container. Because the syn

is only the pointer like the free memory side of the object to move the size of the distance.2. Idle list: This applies to memory irregularities, in which case the JVM maintains a memory list that records which memory areas are idle and how large. When assigning space to an object, go to the free list to find the appropriate area and assign it.But the JVM can't always run in a single-threaded state, so inefficient. Because it is not an atomic operation to allocate memory to an object at least,

First, the parallel worldMoore's law expires in the fall of 2004, Intel announced a total cancellation of the 4GHZ program, CPU to multi-core development, top computer scientist Donald, Knus, and the evaluation: in my opinion, this phenomenon (concurrency) is more or less due to the hardware designers have done nothing to cause, They take the responsibility for Moore's law invalidation to software developers.1. Several conceptsSynchronous and asynchro

occurs, the failed thread causes blocking. Normally blocked threads may spin-wait inside the JVM or be suspended by the operating system. Spin waits can cause more CPU slicing to be wasted, while operating system hangs can cause more context switching.Knowing several aspects of performance improvement, and understanding the overhead of performance, applications are subject to trade-offs and assessments based on actual scenarios. Without once and for all optimization schemes, continuous small-sc

shared variable, he is immediately updated to main memory, and when the other thread reads the shared variable, it reads directly from the main memory.Of course, synchronize and locks can guarantee visibility.Order of Ordering: The order in which the program executes is executed in the order of the Code. In the Java memory model, in order to be efficient, the compiler and processor are allowe

First, prefaceRecently began to learn Java concurrent programming, the learning process recorded. Estimation is not so system, mainly should be the introduction of Java API (not related to the most basic concept introduction), want to go into the system study recommended to read a book "Java Concurrency in practice" (s

instance is not successful because the security of this class is important, and the designer makes the following judgments about it. It detects whether the class calling it is loaded by the startup ClassLoader Bootstrap ClassLoader (its classloader is null), thus guaranteeing that the class can only be used by the class specified by the JVM.public static Unsafe Getunsafe () {Class cc = Sun.reflect.Reflection.getCallerClass (2);if (cc.getclassloader () = null)throw new SecurityException ("Unsafe

0. IntroductionIn the computer world, when people talk about concurrency, it means that a series of tasks are executed simultaneously in the computer. This is true if the computer has multiple processors or multicore processors, and if the computer has only one core processor then it is just a superficial phenomenon.All modern operating systems allow tasks to be performed concurrently. You can read the message while listening to music and surfing the

, and finally get.Of course, if the real data is not ready when called to Future.get (), the blocking condition will still occur until the data is ready to be completed. There are, of course, simpler ways: Import java.util.concurrent.ExecutionException; Import Java.util.concurrent.ExecutorService; Import java.util.concurrent.Executors; Import Java.util.concurrent.Future; public class FutureMain2 {

1.JVM Tuning Summary (1): Some concepts: http://www.importnew.com/18694.html2.JVM Tuning Summary (2): Basic garbage collection algorithm: http://www.importnew.com/18740.html3.JVM Tuning Summary (3): Problems with garbage collection: http://www.importnew.com/18747.html4.JVM Tuning Summary (4): Generational garbage collection: http://www.importnew.com/19255.html5.JVM Tuning Summary (5): Typical configuration: http://www.importnew.com/19264.html6.JVM Tuning Summary (6): A new generation of garbage

Java concurrency Programming: core theory Java Concurrency Programming: synchronized and its implementation principles Java concurrency Programming: Synchronized bottom-level optimization (lightweight lock, biased lock)

,NewMutablepoint (M.get (ID))); returnCollections.unmodifiablemap (result);}Here Mutablepoint is a mutable class, which is thread insecure: Public class Mutablepoint { publicint x, y; Public Mutablepoint () {x = 0; y = 0;} Public mutablepoint (Mutablepoint p) { this. x = p.x; this. y = p.y; }}The attentive reader must have found that almost every method in the Monitorvehicletracker class replicates the value of mutablepoint or locations, because the two are n

IntroductionAs we said in the previous article, volatile is guaranteed visibility, ordering, and "partial" atomicity through the lock command. However, in most concurrency problems, it is necessary to ensure the atomicity of the operation, volatile does not have this function, then need to use other means to achieve the purpose of thread safety, in Java programming, we can through the lock, synchronized key

Deep understanding of Java Virtual Machine: JVM advanced features and best practices (in-depth analysis of JVM Based on issues such as memory management and high concurrency) Provides a comprehensive and in-depth analysis of JVM based on core content such as memory management, execution subsystem, programming compilation and optimization, and efficient concurrency