Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Windows implements the Windows API, which is the primary API for the family of Microsoft operating systems (Windows 98, NT, 2000, and XP, as well as Windows 7). Basically A Windows application runs as a separate process, and each process may contain one or more threads. Additionally, Windows uses the one-to-one mapping, where each user-level thread maps to an associated kernel thread. The general components of a thread include −A thread ID uniquely identifying the threadA set of register representing the status of the processorA stack of user, employed when the thread is running in user mode, and a kernel ... Read More
Many systems implement either the many-to-many or the two-level model place an intermediate data structure between the user and kernel threads. This data structure—typically known as a lightweight process, or LWP—is shown in below Figure. The LWP appears to be a virtual processor on which the application can schedule a user thread to run, to the user-thread library. Each Light Weight Process is attached to a kernel thread, and it is kernel threads that the operating system schedules to run on physical processors. The LWP blocks as well, if a kernel thread blocks (such as while waiting for an I/O ... Read More
One technique for communication between the user-thread library and the kernel is known as scheduler activation. It works as likes: The kernel provides an application with a set of virtual processors (LWPs), and the application can schedule user threads onto an available virtual processor. Moreover, the kernel must inform an application about certain events. This procedure is known as an upcall. Upcalls are handled by the thread library with an upcall handler, and upcall handlers must run on a virtual processor. One event that triggers an upcall occurs when an application thread is about to block. In this scenario, the ... Read More
Threads share the data of the process to which it belongs to. This data sharing provides one of the benefits of multithreaded programming. However, in some circumstances, each thread might need its own copy of certain data. Such data is called thread-local storage (or TLS).For example, in a transaction-processing system, we might service each transaction in a separate thread. Each transaction might be assigned a unique identifier. To associate each thread with its unique identifier, we could use thread-local storage.It is easy to puzzle TLS with local variables. During a single function invocation only local variables are visible, whereas TLS ... Read More
Signals are software interrupts which sent to a program to indicate that an important event has occurred. A Signal may be handled by following one of two possible handlers:A default signal handlerA user-defined signal handlerA Default signal handler is associated with every signal that the kernel runs when handling that signal. The action that a script or program performs when it receives a signal is called the default actions. A default signal handler handles these types of different default actions.Some of the possible default actions are −Terminate the process.Ignore the signal.Dump core. It creates a file called core containing the ... Read More
Signals are software interrupts which sent to a program to indicate that an important event has occurred. This events can vary from user requests to illegal memory access errors. Some signals, such as the interrupt signal, indicate that a user has asked the program to do something that is not in the usual flow of control. Depending on the source of and the reason for the event being signaled, A Signal can be either synchronously or asynchronously. All signals, whether synchronous or asynchronous, follow the same pattern −The occurrence of a particular event generates a signal.Next, the signal is delivered ... Read More
Pthreads refers to the POSIX standard (IEEE 1003.1c) defining an API for thread creation and synchronization. This defines specification for thread behavior, not an implementation. The specification can be implemented by OS designers in any way they wish. So many systems implement the Pthreads specification; most are UNIX-type systems, including Linux, Mac OS X, and Solaris. Although Windows doesn’t support Pthreads natively, some third-party implementations for Windows are available. The C program shown in Figure 4.9 demonstrates the basic Pthreads API for constructing a multithreaded program that calculates the summation of a nonnegative integer in a separate thread. Separate threads ... Read More
Implicit ThreadingOne way to address the difficulties and better support the design of multithreaded applications is to transfer the creation and management of threading from application developers to compilers and run-time libraries. This, termed implicit threading, is a popular trend today.Implicit threading is mainly the use of libraries or other language support to hide the management of threads. The most common implicit threading library is OpenMP, in context of C.OpenMP is a set of compiler directives as well as an API for programs written in C, C++, or FORTRAN that provides support for parallel programming in shared-memory environments. OpenMP identifies ... Read More
Threads are created in the Windows API using the CreateThread() function, and—just as in Pthreads—a set of attributes like security information, the size of the stack, and a flag for the thread is passed to this function. In the below program, we use the default values for these attributes. (The default values do not initially set the thread to a suspended state and instead make it eligible to be run by the CPU scheduler.) Once the summation thread is created, the parent must wait for it to complete before outputting the value of Sum, as the value is set by ... Read More
Pthreads refers to the POSIX standard (IEEE 1003.1c) defining an API for thread creation and synchronization, which is a specification for thread behavior, not an implementation. This specification may be implemented by Operating-system designers in any way they wish. The C program shown in below, demonstrates the basic Pthreads API for constructing a multithreaded program that calculates the summation of a nonnegative integer in a separate thread. Separate threads begin execution in a specified function, in a Pthreads program. In below program, this is the runner() function. When the program begins, a single thread of control begins in main(). main() ... Read More