concurrency and multithreading

PackageGz.itcast.e_thread;Importjava.io.IOException;Importjavax.servlet.ServletException;ImportJavax.servlet.http.HttpServlet;Importjavax.servlet.http.HttpServletRequest;ImportJavax.servlet.http.HttpServletResponse;/*** Multithreading concurrency issues for Servlets *@authorAPPle **/ Public classTheraddemoextendsHttpServlet {intCount = 1; Public voiddoget (httpservletrequest request, httpservletresponse re

solves this problem for us. After the online pool submits the callable task, a future object is returned, using which we can know the status of the callable task and get the result of the execution callable returned. The future provides a get () method so that we can wait for callable to end and get its execution results.What is Futuretask?Futuretask is a fundamental implementation of the future, and we can use it with executors to handle asynchronous tasks. Usually we do not need to use the Fu

class mywaitnotify3{ monitorobject mymonitorobject = new Monitorobject (); Boolean wassignalled = false; public void dowait () { synchronized (mymonitorobject) {while (!wassignalled) { try{ Mymonitorobject.wait (); } catch (Interruptedexception e) {...} } Clear signal and continue running. wassignalled = false; } } public void Donotify () { synchronized (mymonitorobject) { wassignalled = true; Mymonitorobject.notify ();}}} 6.

callable in a thread pool. Since the callable task is parallel, we must wait for it to return the result. The Java.util.concurrent.Future object solves this problem for us. After the online pool submits the callable task, a future object is returned, using which we can know the status of the callable task and get the result of the execution callable returned. The future provides a get () method so that we can wait for callable to end and get its execution results.3: What is Futuretask?Futuretas

, Synchronization=true)]public static Hashtable Synchronized (Hashtable table){if (table = = null){throw new ArgumentNullException ("table");}return new synchashtable (table);}Synchashtable Several common methods, we can see that the internal implementation has added the LOCK keyword to ensure thread safetypublic override void Add (object key, Object value){Lock (this._table. SyncRoot){This._table. ADD (key, value);}}public override void Clear (){Lock (this._table. SyncRoot){This._table. Clear (

This article describes the PHP multithreading concurrency implementation method. Share to everyone for your reference, specific as follows: In Java, multithreading is a new thread of things, PHP relies on the Apache Linux Bottom has a multithreaded approach. Here's how to simulate PHP concurrency if you can't control

without first checking. A typical example of the Set method is the Unlock () method in the lock class. A thread holding a lock is always able to unlock successfully without checking that the lock is in an unlocked state.The program flow of the set method is usually as follows: Set internal state Notifies the waiting thread Here is an example of the Unlock () method: Public class lock{ Privatebooleanfalse; Public synchronized void unlock () { false; Notify (

://my.oschina.net/lifany/blog/133513Reference: http://blog.csdn.net/aesop_wubo/article/details/75379604. What are the three components of the lock-free algorithm?They are usually made up of three parts:① Cycle②cas (Compareandset)③ fallback---------------------------------------------Gorgeous split-line-------------------------------------After JDK 1.5 is scheduledexecutorservice, it is not recommended to use Java.util.Timer because it is not as functional as ScheduledexecutorservicePessimistic l

variable, because the Addtopic () method is non-thread-safe, a new Topicdao instance (not singleton) must be created when it is used. The following uses Threadlocal to transform Conn, a non-thread-safe "state":Code Listing 4 Topicdao: Thread safetyPackage Threadlocaldemo;Import java.sql.Connection;Import java.sql.SQLException;Import java.sql.Statement;public class SqlConnection {① Saving connection variables using threadlocalPrivatestatic threadlocalPublicstatic Connection getconnection () {② I

In Java, multithreading is a new thread of things, PHP relies on the Apache Linux Bottom has a multithreaded approach. Tell me today if you can't manipulate Apache servers, how to simulate PHP concurrency if (function_exists (' Date_default_timezone_set ')) {Date_default_timezone_set (' PRC ');}function A (){$time = time ();Sleep (3);$fp = fopen (' result_a '. $time. Log ', ' W ');Fputs ($fp, ' Set in '.

. Net multithreading, thread Asynchronization, thread synchronization, concurrency issues --- 1 --- ShinePans Application Thread, output thread status: Using System; using System. collections. generic; using System. linq; using System. text; using System. threading; using System. threading. tasks; namespace Main thread 1 {class Program {static void Main (string [] args) {Console. writeLine ("current T

it.Implementation of the blocking queueThe implementation of a blocking queue is similar to an implementation with an upper bound of semaphore. Here is a simple implementation of the blocking queue Public classBlockingqueue {PrivateList queue =NewLinkedList (); Private intLimit = 10; PublicBlockingqueue (intlimit) { This. Limit =limit; } Public synchronized voidEnqueue (Object Item)throwsinterruptedexception { while( This. queue.size () = = This. Limit) {Wait (); } if( This. queue.

object. In this way, only one waiting thread at a time gets awakened, not all waiting threads. This is also the core of achieving fairlock fairness.Note that in the same synchronization block, the lock status is still checked and set to avoid slip-leaking conditions.It should also be noted that Queueobject is actually a semaphore. The dowait () and donotify () methods preserve the signal in Queueobject. This is done to prevent a thread from being re-entered by another call to unlock () and call

the Unlock () method, but look at the implementation of the previous unlock () you will find that it calls the Queueobject.notify (). However, because the thread in lock () has not had time to call Queueobject.wait (), the queueobject.notify () call has no effect, and the signal is lost. If the thread calling lock () calls Queueobject.wait () after another thread calls Queueobject.notify (), the thread will block until the other thread calls the Unlock method, but this will never happen.The pro

is done by the operating system and is related to the I/O port, and there is an I/O completion port for each Io_service instance.Three, asynchronous event separatorsUsed by ASIO to perform event-out operations, all of which are bound to the event handler function.Advantage:First, portability.Many operating systems provide native asynchronous I/O interfaces (such as the I/O overloaded interfaces above windows), which may be implemented with native asynchronous I/O. However, if native support is

workload is reduced, multithreading overhead is much smaller than the multi-process.Cost of sharing: data is accessed by multiple threads and must be guaranteed that the data accessed by each thread is consistent.Threads are limited resources, and too many threads running at the same time consume a lot of operating system resources, making the operating system run more slowly on the whole.Each thread requires a separate stack space, and too many thre

the calculation to complete, and to get the results of the calculation. You can only use the Get method to get the results after the calculation is complete and, if necessary, block this method before the calculation is complete. Cancellation is performed by the Cancel method. Other methods are provided to determine whether the task is completed properly or canceled.The Futuretask class is an implementation of the future, and the class also implements the Runnable interface.7.CompletionService

multithreaded programs, multiple threads are executed concurrently to improve the efficiency of the program, and the CPU does not go idle because a thread needs to wait for resources. Multiple threads share heap memory, so creating multiple threads to perform some tasks is better than creating multiple processes. For example, Servlets is better than CGI because Servlets supports multithreading and CGI does not support it.How does the volatile keyword

is atomic operation. Another example: a++; This operation is actually a = a + 1; is divisible, so he is not an atomic operation. There is a thread-safety problem with non-atomic operations, and we need to use synchronous technology (sychronized) to turn it into an atomic operation. An operation is an atomic operation, so we call it atomic. The Java concurrent package provides some atomic classes, and we can read the API to understand the use of these atomic classes. For example: Atomicinteger,

) {E.printstacktrace ();}}};Mapfor (int i =0;iThread t = new thread (Task);T.currentthread (). SetName ("thread" +i);Map.put (T, T.getname ());}setfor (Thread T:threadset) {T.start ();}try {Thread.Sleep (5000);} catch (Interruptedexception e) {E.printstacktrace ();}SYSTEM.OUT.PRINTLN ("Multithreaded test end ..... ");}@Testpublic void Testhashmapmultithread () {SYSTEM.OUT.PRINTLN ("Multithreaded test begins ..... ");Runnable task = new Runnable () {@Overridepublic void Run () {try {SYSTEM.OUT.PR