reader and writer problem

Transfer from http://blog.csdn.net/zoudaokou2006/article/details/3966694The reader-writer problem is a classic process synchronization problem that is implemented with semaphores. In the system, a data set (such as a file or record) is shared by several concurrent processes, which are divided into two categories, one o

Reader-writer problem (Readers-writers problem) is also a classic concurrent programming problem, which is often a synchronization problem. Data (Files, records) in a computer system are often shared by multiple processes, but som

scheduling class that does not allow preemption.reader Writer's questionProblem description A data object can be shared by multiple concurrent processes. Some of these processes may only need to read the contents of the shared object, while other processes may want to update the contents of the shared object. Reader: Only interested in the process of reading; written by: Other processes (write only, or read and write); Rules allows multiple rea

Internship environment: Windows XP + VC 6.0 Internship objectives: Create a console process in Windows XP, which should contain n threads. Use the n threads to represent n readers or writers. Each thread performs read/write operations according to the requirements of the corresponding test data file (described later. The semaphore mechanism is used to implement reader-first and writer-first issues respectiv

: voidRead () {Printmutex.Lock(); cout"Reader read out:"Endl; Printmutex.unlock (); }protected: voidrun () {Queuemutex.Lock(); Rdcnmutex.Lock(); if(Readercount = =0) {Bmutex.Lock(); } Readercount++; Rdcnmutex.unlock (); Queuemutex.unlock (); Sleep (1); Read (); Rdcnmutex.Lock(); Readercount--; if(Readercount = =0) {bmutex.unlock (); } rdcnmutex.unlock (); }};intReader::readercount =0; Qmutex

blockE.printstacktrace (); }} mlatchdown.countdown (); } } Public classWriter extends Thread { PublicString name =NULL; Boolean flag=true; Private intindex =0; Private intCash =0; PublicWriter (String name,intAddcash) { This. Name =name; This. Cash =Addcash; } @Override Public voidrun () {System. out. println ("[Writer]"+ name +"Start"); while(flag) {Try{Mreadwritelock.writelock ().Lock(); System. out. println ("[

Question 1: readers Level 1: Only readers are allowed. A maximum of K readers are allowed to write programs using P and V Operations. int main(){ int rspace = k; cobegin read_1(); read_2(); …… read_n(); coend}read_i(){ p(rspace); …… v(rspace);} In this operation, you need to set the signal rspace to determine whether the number of people has reached K. When the number of people reaches K, rspace = 0. In this case, you need to suspend. Level 2: One

Problem definition:Existing piece of shared memory, multiple read processes, and multiple write processes. Multiple read processes can be read at the same time, but no other read or write processes are executed when there is a write process in progress.There are 3 variants of the problem. The first is called "Reader First" (readers-preference). In this case, as l

Code can run, but it is really not observed what the reader first, or write a priority. It is not known where this priority conflict is coming from, and it does not know what the book says. Especially in the writer of the following code, if Sem_wait (z) is introduced, the writer process blocks, causing the reader to bl

1. First, the reader's semaphore implementation Set three mutex semaphores: Rwmutex is used to access Shared data that is mutually exclusive to other readers/writers. Rmutex is used to access the reader counter readcount that is mutually exclusive to the reader. Wmutex is used by the writer to wait for the reader t

possible, although not all of the text is required immediately, so that later reading speed can be faster. When the program writes a bufferedwriter, the text is placed in the buffer. Text is moved to the underlying output stream or other targets only when the buffer is full or when the writer refreshes the output explicitly, which makes writing much faster. Bufferedreader and bufferedwriter also have common methods associated with the

As with the producer consumer Problem of the second multi-threaded tenth producer Consumer problem , reader writer is also a very famous synchronization problem. The reader writer's question description is very simple, there is a

We use events and a variable that records the number of readers to solve reader-writer problems in the second-to-last multi-threaded 11th article Reader-writer question. The problem has been solved, but the code is a bit complicated. This article will introduce a new method-

requirements to meet the time of production, which for critical resources access will produce a certain sequence, Will increase the read speed of resources within the system. consumers point to a location where there are valid data, the producer points to the location is not valid data, and the pipe ring buffer similar to the pipe of the ring buffer to take a look at understanding it. in this picture, you can think of write as a producer, in the production of data, read can be seen as a consume

followed by a stream of bytes, the following main introduction character stream, character stream and byte stream difference and file copy copy. In the program, a character equals two bytes, and a Chinese character occupies two bytes (General Limited interview will ask: A char can save a Chinese character, the answer is, of course, a char and a Chinese character accounted for two bytes), the general use of byte stream if defined as odd number of length is, then stored Chinese characters will hav

++) {Handle[i]= (HANDLE) _beginthreadex (NULL,0, Readerthreadfun, NULL,0, NULL); } waitformultipleobjects (Readernum+1, handle, TRUE, INFINITE); for(i =0; I 1; i++) {CloseHandle (handle[i]); } //destroying events and semaphoresCloseHandle (G_heventwriter); CloseHandle (G_heventnoreader); DeleteCriticalSection (CS); DeleteCriticalSection (cs_readernum); //Detecting Memory leaks_CrtDumpMemoryLeaks (); return 0;}I was thinking about whether to use the semaphore, and later to see http://blog.

consume data when the buffer is empty.To solve this problem, you must let the producer hibernate when the buffer is full, until the next time the consumer consumes the data in the buffer, the producer can be awakened and begin adding data to the buffer. Similarly, you can let consumers hibernate when the buffer is empty, wait until the producer adds data to the buffer, and then wake the consumer.3. Difference1) The data has been there, there is no va

This is a creation in Article, where the information may have evolved or changed. "Go language Combat" reading notes, not to be continued, welcome to sweep code attention flysnow_org to the public or website http://www.flysnow.org/, the first time to see follow-up notes. If you feel helpful, share it with your friends and thank you for your support. Input and output The Go Writer and reader interf

1.Reader WriterWhen we first saw the Reader and Writer classes, we might think that this was two classes to replace InputStream and Outputstreamt , but that is not the case.Although some of the original "stream" libraries are no longer used (if they are used, you will receive compiler warning messages), InputStream and Outputstreamt can still provide valuable fu

Source: http://dantvt.spaces.live.com reader-Writer Problem Writer Priority and fair competition multi-process mutual access to shared resources and Process Synchronization of the classic problem has a file F, access is required for multiple concurrent read and write process