mastering concurrency programming with java 8

Writing thread-safe code is essentially managing access to the state , and is usually a shared, mutable state . The so-called sharing refers to a variable is accessed by multiple threads, so-called mutable refers to the value of a variable can be changed in its life cycle.The nature of thread safety depends on how the object is used in the program, not what the object accomplishes. It is easier to design a class as thread-safe from the beginning than to modify it at a later stage.First, the conc

The omission of notify notice is easy to understand, that is, Threada has not started wait time, THREADB has notify, so, THREADB notice is not any response, when threadb exit synchronized code block, Threada starts waiting again and then waits until it is interrupted by another thread.See Example: Https://git.oschina.net/wenjieyatou/threadTestBefore THREADB notifies, the Oktoproceed is set to true so that if Threada misses the notification, it will not enter the while loop, and the wait method w

. IsEmpty ()) { return This. Dotake (); } //if the queue is empty, sleep for a few seconds and try again} thread.sleep (sleep_granularity); } } }4. Conditional queue Packagecn.xf.cp.ch14;/*** function: Use condition queue * Time: 3:32:04 * File: Boundedbuffer.java *@authorAdministrator * *@param*/ Public classBoundedbufferextendsBaseboundedbuffer{ PublicBoundedbuffer (intcapacity) { Super(capacity); } /*** Add Data element *@paramv *@thr

1, if more than one thread accesses the same mutable state variable when not using the appropriate synchronization, then the program will be an error, there are three ways to fix the problem: This state variable is not shared between threads. Modify the state variable to a variable that is immutable. use synchronization when accessing state variables. 2. What is thread-safe? This class is thread-safe when multiple threads access a class, regardless of how the runtime envir

. If operation A is performed before action B and action B is performed before Operation C, then operation a must be performed before Operation C.The following is an English description of happens-before,the Happens-before relation defines when data races take place. An unlock in a monitor happens-before every subsequent lock on the that monitor. A write to a volatile field happens-before every subsequent read of the that field. A call to start () on a thre

@ 20:58:43by outputting The results, we can find several problems. After 1.NotifyThread calls the Notifyall () method, Waitthread does not return immediately from the Wait () method.Because of this time Notifythread did not release the lock. 2. Program 61 Line,notifythread the first release of the lock, however waitthread do not make up, and did not grab this lock. Still in blocked state. 3. Until 67 lines. Notifythread Release the lock once again. Waitthread Gets the lock, which returns from W

1. Several ways to stop a thread 1.1 General Logic stops public class ThreadInterruptTest { public static volatile boolean cancel = true; public static void main(String[] args) throws InterruptedException { Thread thread = new Thread( new Runnable() { @Override public void run() { while (cancel) { System.out.println("still alive"); }

Volatile provides a weak synchronization mechanism to ensure that variable updates are notified to other threads. Volatile variables are not cached in registers or invisible to other processors, so the most recent write value is always returned when reading a volatile variable. You can imagine the following semantics, but volatile is a more lightweight synchronization mechanism.volatile can only ensure visibility, but it does not guarantee atomicity. In other words, it cannot be used in composit

adds an element to the current thread: T1 adds an element to the current thread: T1 added an element the current thread receives notification: t2list size = 5, thread stop exception in Thread "T2" Java.lang.RuntimeExceptionat sync. Waitandnotify$2.run (waitandnotify.java:73) at Java.lang.Thread.run (Unknown Source)　　Code interpretation:The first step: Execute T2 thread, enter the Run method, list.size not equal to 5, lock.wait release lock, T2 process Wait, turn to execute T1Second step: Execut

the old value, do not find the same key is added to the end of the list If it's a red and black tree, Finally go back to determine whether to reach the threshold, such as arrival into the red and black tree structure. Method of Use: Treeifybin (tab, i); The Get () method does not have a lock operation, the steps are as follows: First, locate the I in table[]. If Table[i] exists, continue to find. First, the linked list header is compared, and if yes

can use the set in println, you must first get the iteratortest lock, but this requirement is often overlooked in debug code and in log code .Accordingly, the container's hashcode and equals methods also perform iterative operations indirectly, which occurs when the container is an element or a key value of 01 containers. Similarly, methods such asContainsall,removeall , and Retainall , as well as constructors that use containers as parameters, iterate over the container. All of these indirect

Similar to the multi-tasking scenario of a Web server, it is not possible to use only one thread to provide services externally. This way, efficiency and throughput are too low.However, it is not possible to create a thread with a single request because the cost of creating the thread is very high and the number of threads that the system can create is limited.So the executor appeared.The meaning of executor frame thread poolThread creation too little wasted server resources, in addition to the

of the busy cycleA looping statement designed to consume time22. The method that lets one thread wait for another thread to dieJoin ()23. The thread method that lets you sleepSleep ()24. Write an application called Intsleep, which creates a background thread, continuously prints out Hello, and then sleeps 100ms. After sleeping 2s, the default main thread should interrupt the background thread, which jumps out of the loop after printing out the interruptedpublic class Intsleep {public static voi

second method is similar to the first, except for a nanosecond-time parameter. Copycat This article is from the "Java 7 Concurrency Cookbook" (D-Gua to "Java7 concurrent Sample Set") translation, only as learning materials used. No authorization shall be applied to any commercial act. Small has become The full version of the sample code used in this section. Complete code for the Datasourcesloader cla

Scheduledfuturetask contains 3 variables: Long variable time, which is the task's specific execution times The long variable sequencenumber is the ordinal of the task that is added to the Scheduledthreadpoolexecutor Long member period, which indicates the interval between task execution Here are scheduledthreadpoolexecutor specific steps to perform: The thread gets the scheduledfuturetask that has expired from Delayqueue. An expiration task is a task that has a ti

make Mutableinteger a thread-safe class, as follows:[Java]View PlainCopy Public class Synchronizedinteger { private int value; public synchronized int get () { return value; } public synchronized void set (int value) { this.value = value; } } The set and get methods are synchronized, with the same object lock, so that the Get method can see the change in the value of the set method, so that the value of values obtain

know that some methods of blocking threads will throw interruptedexception to indicate that a thread break occurs, in which case a thread break can be used to terminate the thread's operation: Public classTestinterrupt { Public Static voidMain (string[] args) {BlockingqueueNewLinkedblockingqueue(); Consumer Consumer=NewConsumer (Objectqueue); Thread T=NewThread (consumer); T.start (); //waiting for thread to start Try{Thread.Sleep (1000); } Catch(interruptedexceptio

of the thread-safe classes are relatively thread-safe, which guarantees thread-safe operation of the object individually, and we do not need additional safeguards when calling, but for some specific sequential calls, It may be necessary to use an additional synchronization method at the caller's side to ensure the correctness of the call. Examples include vectors, HashTable, Collections's Synchronizedxxxx () method wrapper collections, and so on."Java