c# generating barcode Part V in VS .NET

Creation QR in VS .NET Part V

Part V
Quick Response Code Generator In Visual Studio .NET
Using Barcode drawer for ASP.NET Control to generate, create QR Code 2d barcode image in ASP.NET applications.
www.OnBarcode.com
Making Barcode In .NET Framework
Using Barcode maker for ASP.NET Control to generate, create barcode image in ASP.NET applications.
www.OnBarcode.com
Threading
Generate QR Code JIS X 0510 In Visual C#.NET
Using Barcode generation for .NET Control to generate, create QR Code image in .NET applications.
www.OnBarcode.com
QR Code ISO/IEC18004 Drawer In VS .NET
Using Barcode encoder for Visual Studio .NET Control to generate, create Quick Response Code image in .NET applications.
www.OnBarcode.com
one block of code with a lock, then the data will become corrupted . Also, there is no way to prove that you have added all your locking code correctly . You just have to run your application, stress-test it a lot, and hope that nothing goes wrong . In fact, you should test your application on a machine that has as many CPUs as possible because the more CPUs you have, the better chance that two or more threads will attempt to access the resource at the same time, making it more likely you ll detect a problem . The second problem with locks is that they hurt performance . It takes time to acquire and release a lock because there are additional method calls and because the CPUs must coordinate with each other to determine which thread will acquire the lock first . Having the CPUs in the machine communicate with each other this way hurts performance . For example, let s say that you have code that adds a node to the head of a linked list:
Encoding QR In VB.NET
Using Barcode maker for Visual Studio .NET Control to generate, create QR Code ISO/IEC18004 image in VS .NET applications.
www.OnBarcode.com
Printing PDF-417 2d Barcode In .NET
Using Barcode maker for ASP.NET Control to generate, create PDF 417 image in ASP.NET applications.
www.OnBarcode.com
// This class is used by the LinkedList class public class Node { internal Node m_next; // Other members not shown } public sealed class LinkedList { private Node m_head; public void Add(Node newNode) { // The two lines below perform very fast reference assignments newNode.m_next = m_head; m_head = newNode; } }
Bar Code Creation In Visual Studio .NET
Using Barcode printer for ASP.NET Control to generate, create bar code image in ASP.NET applications.
www.OnBarcode.com
Barcode Drawer In .NET Framework
Using Barcode encoder for ASP.NET Control to generate, create bar code image in ASP.NET applications.
www.OnBarcode.com
This Add method simply performs two reference assignments that can execute extremely fast . Now, if we want to make Add thread safe so that multiple threads can call it simultaneously without corrupting the linked list, then we need to have the Add method acquire and release a lock:
Bar Code Drawer In .NET Framework
Using Barcode generator for ASP.NET Control to generate, create barcode image in ASP.NET applications.
www.OnBarcode.com
Make Data Matrix In .NET
Using Barcode drawer for ASP.NET Control to generate, create DataMatrix image in ASP.NET applications.
www.OnBarcode.com
public sealed class LinkedList { private SomeKindOfLock m_lock = new SomeKindOfLock(); private Node m_head; public void Add(Node newNode) { m_lock.Acquire(); // The two lines below perform very fast reference assignments newNode.m_next = m_head; m_head = newNode; m_lock.Release(); } }
Code-128 Encoder In .NET Framework
Using Barcode generator for ASP.NET Control to generate, create Code 128 Code Set C image in ASP.NET applications.
www.OnBarcode.com
USPS Confirm Service Barcode Maker In .NET
Using Barcode creation for ASP.NET Control to generate, create USPS PLANET Barcode image in ASP.NET applications.
www.OnBarcode.com
While Add is now thread safe, it has also become substantially slower . How much slower depends on the kind of lock chosen; I will compare the performance of various locks in this chapter and in 29, Hybrid Thread Synchronization Constructs . But even the fastest
QR Code Recognizer In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Making ANSI/AIM Code 39 In Java
Using Barcode encoder for Android Control to generate, create Code 39 image in Android applications.
www.OnBarcode.com
28
PDF417 Reader In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Barcode Printer In Java
Using Barcode creation for Java Control to generate, create barcode image in Java applications.
www.OnBarcode.com
Primitive Thread Synchronization Constructs
Painting UCC.EAN - 128 In Objective-C
Using Barcode generator for iPad Control to generate, create USS-128 image in iPad applications.
www.OnBarcode.com
Read PDF-417 2d Barcode In .NET Framework
Using Barcode scanner for Visual Studio .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
lock could make the Add method several times slower than the version of it that didn t have any lock code in it at all . Of course, the performance becomes significantly worse if the code calls Add in a loop to insert several nodes into the linked list . The third problem with thread synchronization locks is that they allow only one thread to access the resource at a time . This is the lock s whole reason for existing, but it is also a problem because blocking a thread causes more threads to be created . So, for example, if a thread pool thread attempts to acquire a lock that it cannot have, it is likely that the thread pool will create a new thread to keep the CPUs saturated with work . As discussed in 25, Thread Basics, creating a thread is very expensive in terms of both memory and performance . And to make matters even worse, when the blocked threads gets to run again, it will run with this new thread pool thread; Windows is now scheduling more threads than there are CPUs, and this increases context switching, which also hurts performance . The summary of all of this is that thread synchronization is bad, so you should try to design your applications to avoid as much of it as possible . To that end, you should avoid shared data such as static fields . When a thread uses the new operator to construct an object, the new operator returns a reference to the new object . At this point in time, only the thread that constructs the object has a reference to it; no other thread can access that object . If you avoid passing this reference to another thread that might use the object at the same time as the creating thread, then there is no need to synchronize access to the object . Try to use value types because they are always copied, so each thread operates on its own copy . Finally, it is OK to have multiple threads accessing shared data simultaneously if that access is read-only . For example, many applications create some data structures during their initialization . Once initialized, the application can create as many threads as it wants; if all these threads just query the data, then all the threads can do this simultaneously without acquiring or releasing any locks . The String type is an example of this: Once a String object is created, it is immutable, so many threads can access a single String object at the same time without any chance of the String object becoming corrupted .
Barcode Encoder In Java
Using Barcode printer for Eclipse BIRT Control to generate, create bar code image in BIRT reports applications.
www.OnBarcode.com
PDF-417 2d Barcode Generator In None
Using Barcode generator for Online Control to generate, create PDF-417 2d barcode image in Online applications.
www.OnBarcode.com
Copyright © OnBarcode.com . All rights reserved.