java concurrency in practice amazon

mask the necessary code optimizations in the JVM, so use this keyword when necessary. ------------------------------------------------------------------------------------------excerpted from Http://www.ibm.com/developerworks/cn/java/j-jtp06197.htmlThe Java language contains two intrinsic synchronization mechanisms: synchronous blocks (or methods) and volatile variables . Both of these mechanisms are propo

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

: Copy Code code as follows: Thread.Interrupt (); 8. Perform the example to see the execution effect. Know the reason why When you execute this program, you will find out how the program prints a Date object every second, and when the thread is interrupted. When the sleep () method is invoked, the thread leaves the CPU and stops execution for a period of time. During this time, the thread does not need the CPU, so the CPU can perform other tasks. When a thread in hiber

{ //in a stable state. Attempt to insert a new node if(CurTail.next.compareAndSet (NULL, NewNode)) { //Insert successful, try to push tail node, this step can be helped by another thread if it is not completedTail.compareandset (curtail, newNode); return true; } } } } } }}ABA IssuesIn some algorithms, if the value of V is first changed from a to B, then B becomes a.The

the key value pair for that index is not what we are looking for, the next index position is computed by the Nextindex method until the target key value pair is found or empty. Hash conflict: Elements at the same index position in HashMap are kept in the same index position in a linked list, whereas in Threadlocalmap, the data structure of the linked list is not used, but instead (the current index position + 1) The result of the length modulus as the location of the same index element: The N

"Java concurrency" executor framework mechanism and thread pool configuration usage One, executor frameworkThe executor framework, introduced in Java 5, uses a thread pool mechanism that simplifies concurrent programming operations by controlling the start, execution, and shutdown of threads under the Java.util.cocurrent package. Therefore, after

Thread Starvation DeadlockThe explanation for thread starvation deadlocks in Java Concurrency Programming practice is that when you use a thread pool to perform a task, a deadlock problem can occur if the task relies on other tasks. In a single-threaded executor, if one task submits another task to the same executor and waits for the result of this committed task

ends The Business");Bankservicewindows.unhandle ();}};Thread Jay=new thread () {public void Run () {Bankservicewindows.handle ();System.out.println ("Jay begins to transact business");try {This.sleep (5000);} catch (Interruptedexception e) {E.printstacktrace ();}System.out.println ("Jay ends the Business");Bankservicewindows.unhandle ();}};Tom.start ();Jim.start ();Jay.start ();}}The possible output results are:Tom starts to transact businessJay starts to transact businessJay ends Processing bu

Introduction to the first chapter Pick a book Threads share process-wide resources such as memory handles and file handles, but each thread has its own program counter (Programs Counter), stacks, and local variables. Multiple threads in the same program can also be scheduled to run on multiple CPUs at the same time. Chapter II Thread Safety Pick a book The primary synchronization mechanism in Java is the keyword synchronized, which prov

line of the JIT compiler is just a matter of academic practice for locking double checks.However, since JAVA2, the JMM has undergone a fundamental change, allocating space, initializing, calling the construction method only to complete the working store of the thread, withoutWhen you copy assignments to the primary store, the process is absolutely not visible to other threads. And this field is copied to the main memory area of the process, and there

{ privatefinalnew hashset(); Public threestooges () { stooges.add ("one"); Stooges.add ("both"); Stooges.add ("three"); } Public Boolean Isstooge (String name) { return stooges.contains (name);} }3.4.1 Final DomainIn the Java memory model, the final domain also has a special semantics. The final domain ensures the security of the initialization process, which allows unrestricted access to immutable obje

then the network inside, is the heart of the eternal scar ~ 9. A solution for atomicity, performance issues//In complex scenarios, use multiple atomic classes of objects Public classCachefactorizerImplementsservlet{PrivateBigInteger Lastnumber;PrivateBiginteger[] lastfactors;Private LongHitsPrivate LongCachehits; Public synchronized Long gethits(){returnHits } Public synchronized Double Getcachehitradio(){return(Double) Cachehits/(Double) hits; } Public void Service(ServletRequest req, Ser

Java Concurrency Programming-the 2nd chapter-Thread Safety2. Thread Safety2.1 What is thread safetyThread-Safe classes: When a class is accessed by multiple threads, how these threads are executed alternately, regardless of how they are dispatched in the running environment, does not require the amount of synchronization or synergy in the code portion of the call. This class is a thread-safe classThread-saf

guarantees that any thread reading the domain will see the value that was recently written.The increment operator (+ +) is not atomic. Divide two operations, read the value first, and then write a new value.You can add the synchronized modifier. You can then remove the volatile modifier.Best practice is to use class Atimiclong to perform better than synchronizedWhen multiple threads share variable data, each thread that reads or writes data must perf

Shutdownnow method tries to stop all active tasks that are being performed, pauses processing of the awaited task, and returns a list of tasks waiting to be executed. Thread pool Optimization-intsmaze In general, determining the size of the thread pool requires considerations such as the number of CPUs, memory size, JDBC connectivity, and so on. In the Java Concurrency Programming

Recently, the Java concurrent programming combat-java consurrency in practice has been reviewed, and some of the common tools mentioned in the book are recorded here:I. Latching (door bolt)-CountdownlatchScenario: multithreaded testing, usually in order to accurately timing, requires all the threads ready to start execution, to prevent the cable enters upgradeabl

modify its value directly by reflection.The atomicmarkablereference class describes an The atomicstampedreference class maintains an object reference with an integer "flag" that can be updated atomically. Comparing the atomicmarkablereference class,atomicstampedreference maintains a similar Atomicinteger , this data structure can carry an object reference, and the ability to atomically manipulate both the object and the count.The "ABA Problem" is mentioned in later chapters, and atomicmarkabler

Java concurrency (basic knowledge)-blocking queue and producer consumer Mode1. Blocking Queue BlockingQueue is a thread-safe Queue version. It can be seen from its name that it supports blocking Queue implementation: When requesting data from an empty BlockingQueue, it will block BlockingQueue to a non-empty value. When inserting data into a full BlockingQueue, the thread will block BlockingQueue to be inse

(); Thread T=NewThread (NewMessageloop ()); T.start (); Threadmessage ("Waiting for Messageloop thread to finish"); //Loop until Messageloop//thread Exits while(T.isalive ()) {Threadmessage ("Still Waiting ..."); //Wait Maximum of 1 second//For Messageloop thread//To finish.T.join (1000); if((System.currenttimemillis ()-StartTime) >Patience)t.isalive ()) {Threadmessage ("Tired of waiting!"); T.interrupt (); //shouldn ' t be a long now//--Wait indefinitelyT.join ();

;" +getupdater ("value2"). Incrementandget (data)); System.out.println ("2 ==>" +getupdater ("Value3"). Decrementandget (data)); System.out.println ("True ==>" +getupdater ("Value4"). Compareandset (Data, 4, 5)); } Public Static voidMain (string[] args) {Atomicintegerfieldupdaterdemo demo=NewAtomicintegerfieldupdaterdemo (); Demo.doit (); }} In the example above, the Demodata field value3/value4 is not visible to the Atomicintegerfieldupdaterdemo class, so it is not possible to modify its