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| | Semaphore (programming) - Wikipedia, the free encyclopedia |
 | | The trend in programming language development, though, is towards more structured forms of synchronization, such as monitors and channels. | | | In addition to their inadequacies in dealing with deadlocks, semaphores do not protect the programmer from the easy mistakes of taking a semaphore that is already held by the same process, and forgetting to release a semaphore that has been taken. | | | (If there is only one resource, a "binary semaphore" with values 0 or 1 is used.) The P operation busy-waits (or maybe sleeps) until a resource is available, whereupon it immediately claims one. |
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http://en.wikipedia.org/wiki/Semaphore_(programming)
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| | Charles Babbage Institute: RESEARCH PROGRAM> Current research |
| | Semaphores are a programming mechanism for organizing, solving, and implementing synchronization solutions, but without many of the disadvantages mentioned above. | | | Solutions using conventional programming constructs exist, but these are extremely complex, inefficient, difficult to understand and analyze, and brittle in the sense that small changes in the problem or environment could invalidate them. | | | Another early system with semaphores, but implemented as a microprogram rather than as conventional software, was Venus (qv). |
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http://special.lib.umn.edu/cbi/shp/entries/semaphores.html
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| | Wikinfo Computer science |
| | Edsger Dijkstra, for algorithms, Goto considered harmful, the semaphore (programming), rigor, and pedagogy. | | | Computer programming or software development is the act of writing program code. | | | Linguistics is the study of languages, converging with computer science in such areas as programming language design and natural language processing. |
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http://www.wikinfo.org/wiki.php?title=Computer_science
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| | Intro to System Software, Chapter 17 |
| | A simple or binary semaphore is a semaphore which has only two values, zero and one; when used to solve the mutual exclusion problem, the value zero indicates that some process has exclusive use of the associated resource and the value one indicates that the resource is free. | | | In a sense, semaphores are something like the goto statement in early programming languages; they can be used to solve a variety of problems, but they impose little structure on the solution and the results can be hard to understand without the aid of numerous comments. | | | Semaphores can be used to solve the mutual exclusion problem at the user level; for example, consider the code fragments shown in Figure 17.1. |
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http://www.cs.uiowa.edu/~jones/syssoft/notes/17conc.html
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| | Compilers - Chapter 18 |
| | Secondly, concurrent programming facilities may allow some kinds of programs to be designed and structured more naturally in terms of autonomous (but almost invariably interacting) processes, even if these are executed on a single processing device, where their execution will, at best, be interleaved in real time. | | | A common way of introducing programming to novices is by the preparation of a recipe or algorithm for some simple human activity, such as making a cup of tea, or running a bath. | | | You might like to consider other restrictions on the use of semaphores, such as allowing initial assignment only within the parent process (main program), forbidding assignment of negative values, and restricting the way in which they can be used as parameters to procedures, functions or processes (you will need to think very carefully about this). |
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http://scifac.ru.ac.za/compilers/cha18s.htm
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| | docs.sun.com: Multithreaded Programming Guide |
| | In the P operation, the semaphore's value must be positive just before it is decremented (resulting in a value that is guaranteed to be nonnegative and one less than what it was before it was decremented). | | | However, semaphores are not as efficient as mutex locks. | | | The semantics of the operation are such that the thread must wait until the semaphore's value is positive, then change the semaphore's value by subtracting one from it. |
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http://docs.sun.com/app/docs/doc/805-5080/6j4q7emgq?a=view
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| | Semaphore Programming Assignment |
| | Your program will have an elevator class from which an elevator object containing the elevator thread is instantiated, and a person class from which person objects containing a person thread each are instantiated. | | | The input data to your Java program are the number of people in the building, the maximum person building wander time (napping time), the number of floors in the building, the simulation running time, and a flag for deterministic mode. | | | Be sure to (stress) test your program with the following kinds of input data. |
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http://www.mcs.drexel.edu/~shartley/ConcProgJava/Labs/elevator.html
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| | [No title] |
| | Considering that the access to the buffer is exclusive the first semaphore will be a binary one (its value will be 0 or 1), while the second and the third will assume values related to the dimension of the buffer. | | | A different task can be accomplished by the semaphore, the resource counter: the value it represents, in this case, the number of resources available (for example the number of free memory cells). | | | They are arrays of two actions, the first on the semaphore number 1 and the second on the semaphore number 2; while the first is incremented the second is decremented and viceversa, but the policy is no more a wait one: IPC_NOWAIT forces the process to continue execution if the resource is busy. |
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http://www.tldp.org/linuxfocus/English/January2003/article281.meta.shtml
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| | Count Instances of Process or Application in C++ |
| | To implement the algorithm, create a semaphore at program startup set at a high value. | | | Releasing the semaphore increments its value and returns the previous value of the semaphore. | | | The previous value is subtracted from the maximum semaphore value to give the number of instances of the process. |
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http://www.somacon.com/p112.php
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| | Semaphore Programming Assignment |
| | The total number of `W's and `X's that have been output at any point in the output string cannot exceed the total number of `Y's and `Z's that have been output at that point. | | | After a `Y' has been output, another `Y' cannot be output until one or more `Z's have been output. | | | Use binary and counting semaphores for synchronization, as appropriate. |
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http://www.mcs.drexel.edu/~shartley/ConcProgJava/Labs/wxyz.html
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| | [No title] |
| | The name "semaphore" comes from the name for signal flags used on ships; in modern computer systems, semaphores are used to prevent sections of memory from being concurrently read from or written to by different processes. | | | This mailer demonstrates a fairly basic use of semaphores, using them as a generic way of reseting the "busy" status of an object, by allowing the object to be reset either through the passage of time, or through the action of a user. | | | As a reminder, if the semaphore is notified more times than it has commands queued, the semaphore count will become negative and further @waits dependent on that semaphore will be immediately executed, until the semaphore count is zero. |
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http://www.visi.com/~gyles19/CM/man2x3
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| | EDM/2 - The Codesmith's Library |
| | In fact, it talks very little about programming, and a lot about designing programs, as might be expected from its title. | | | As such, in many ways it is much more valuable and important than a "mere" programming book, but it sacrifices programming detail to do this. | | | The few examples that are in the book are in C. Much of the material is inherently bound to C programming, as well. |
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http://www.edm2.com/0301/codesmith.html
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| | Binary semaphore problem - GameDev.Net Discussion Forums |
| | In theory I could simulate a counting semaphore with binary ones but I was under the impression that this is a long-winded approach, and still doesn't solve the problem entirely as I still have to decide which of the 2 resources will be given to a requesting process. | | | My initial thought was that I need a semaphore that signifies "at least one of the two consumers is free", but that's not enough because if both are free I need the other to be getting accessed as well. | | | Maybe the principles from Dekker's algorithm could be applied here, but that was ugly when generalised for 3 processes and 1 resource. |
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http://www.gamedev.net/community/forums/topic.asp?topic_id=304417&whichpage=1&
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| | Win CE Semaphore |
| | NOTE: This test program, because of its use of standard I/O, will not build for operation in the Windows CE emulation environments. | | | The next step is to modify it for operation in the Windows CE emulation environments supported by the Beta release of the Windows CE Development kit. | | | As Windows CE events cannot be named, these simulated semaphores cannot be named either. |
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http://world.std.com/~jmhart/samplece.htm
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| | Introductory Ada Concurrency Summary |
| | In a program where multiple tasks have access to shared variables, the use of the semaphore insures that only one task at a time can access the shared variables (this is called mutual exclusion). | | | Execution of a program or task is delayed by at least the delay time specified in a DELAY statement. | | | The purpose of this document is to provide just enough Ada Concurrency programming information for an entry level student to succeed in a first programming class (Computer Science CS1). |
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http://www.seas.gwu.edu/~csci51/fall99/ada_task.html
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| | [No title] |
| | Basic Programming Examples * Sequential:: A simple sequential program. | | | This would be accomplished by implementing an `Adder' class and having the `main::' method of the `Root' class create an `Adder' process and have it perform the add. | | | We also have `top:' store its received value for later processing and `bottom:' print a message containing both the arguments to `top:' and `bottom:' to demonstrate that computation can be performed using both values. |
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http://www.myri.com/lyric/lyric_prog_man.info
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| | Semaphore - what is that? |
| | A succeeding task may not start until it has received the semaphores from all of it's predecessors; this is the order of communication in which a semaphore is used to 'talk' to all successors. | | | A semaphore is a lot like a locking mechanism, only smarter. | | | My suspection is that this is Apache problem, so i have one reserved optional solution is ask hosting to recomile apache. |
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http://www.ozzu.com/ftopic42616.html
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| | Await && Locks Programming Guide |
| | You program may work in Debug configuration correctly, but when you turn on compiler optimization for Release configuration, volatile may save you from sleepless nights. | | | There can arise deadlock in the multithreaded programs. | | | Here is the class that represents counting semaphore. |
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http://await.sourceforge.net/progg.html
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| | linux gui programming - LinuxQuestions.org |
| | Programming This forum is for all programming questions. | | | I am new to linux also newbie to programming. | | | C++ might better serve you if you were into systems programming or maybe doing graphics |
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http://www.linuxquestions.org/questions/showthread.php?postid=790749
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| | Porting Multithreaded Applications from Win32 to Mac OS X |
| | If you are considering the Cocoa frameworks for your Mac OS X application, you should read the Introduction to the Objective-C Programming Language to familiarize yourself with some of the Cocoa terminology presented here. | | | The fact that the semaphore’s value was incremented is retained, even if there are no waiting threads. | | | Which API you choose depends on a number of factors, including the level of multithreading support required, your familiarity with object-oriented programming (specifically, OOP with Objective-C), your cross-platform objectives, and of course, your schedule. |
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http://developer.apple.com/macosx/multithreadedprogramming.html
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| | Perl semaphore example - Dev Shed |
| | Perl semaphore example Perl Programming forum discussing coding in Perl, utilizing Perl modules, and other Perl-related topics. | | | Does anyone have an example script implementing a file locking semaphore in perl?? | | | Viewing: Dev Shed Forums > Programming Languages > Perl Programming > Perl semaphore example |
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http://forums.devshed.com/perl-programming-6/perl-semaphore-example-50974.html
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| | Semaphore - Wikipedia, the free encyclopedia |
| | Semaphores in computer science, in which only one part of a concurrent system may access a limited resource; this application of mutual exclusion in computing was invented by Edsger Dijkstra | | | Semaphore is a comprehensive integrating accounting software systems | | | A mechanical device (a semaphore signal) used in railway signalling |
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http://en.wikipedia.org/wiki/Semaphore
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| | IPC::Semaphore - SysV Semaphore IPC object class |
| | This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. | | | Sets all values in the semaphore set to those given on the | | | Returns the number of processed waiting for the semaphore |
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http://www.xav.com/perl/lib/IPC/Semaphore.html
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| | Multi-threaded Programming |
| | -- Lock a semaphore and suspend the thread if the semaphore value is zero. | | | -- Creates a new semaphore and assigns an initial value to it. | | | -- Destroys a semaphore that was created by |
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http://www.utdallas.edu/~dbb033000/SDL/html/thread.html
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| | Semaphore |
| | Every multithreaded programming language needs to have some way for the threads to keep in synch. | | | Take, for example, a program with a thread that produces objects and a thread that consumes them, as seen in the following code snippet: | | | * Semaphore is a straightforward implementation of the well-known |
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http://www.javaworld.com/javaworld/javaqa/1999-11/02-qa-semaphore.html
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| | [No title] |
| | A semaphore must be given a non-negative initial value. | | | It is important to be able to distinguish between them because the correctness of a program will depend on the definition being used. ¡ Á Á ðx ð Ã ðH
¿ À ÿ ¨) ¨) ? ¿ ð Ð 0 ð ¢ ð “ ð6 C¿ ¿ À ÿ ð º Ø z ð ¨Ð Blocked-set semaphore : down(S) if S > 0 then S = S - 1 else suspend the action of the process making the call. | | | In particular, we observe the following results. ¡ ¡ 2 ª ðô ¢ ð ð0 $C¿ ¿ À ÿ ð 0à* ð” ¨( For a busy-wait semaphore, starvation is possible. |
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http://www.cs.qub.ac.uk/~NS.Scott/csc321_2001/LectureMaterial/4_csc321.ppt
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| | semaphore - Dev Shed |
| | Viewing: Dev Shed Forums > Programming Languages > PHP Development > semaphore | | | Dev Shed Forums > Programming Languages > PHP Development | | | The system gives back a number which you have to use in the semaphore. |
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http://forums.devshed.com/php-development-5/semaphore-5022.html
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| | Programming in C |
| | How to Divide a Program between Several Files |
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http://www.cs.cf.ac.uk/Dave/C/CE.html
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| | Semaphore api - GameDev.Net Discussion Forums |
| | I need semaphore in my program, what API should I use for that? | | | Posted - 12/16/2005 4:38:43 PM I have found the create_semaphore and wait, but how do I do signal to the semaphore? | | | Is semaphore not a standard user program service in windows? |
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http://www.gamedev.net/community/forums/topic.asp?topic_id=364492
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| | Semaphore - Free Encyclopedia |
| | Semaphore (programming), invented by Edsger Dijkstra for computer science, where only one part of a multitasking system may access a limited resource. | | | This is a disambiguation page; that is, one that just points to other pages that might otherwise have the same name. | | | If you followed a link here, you might want to go back and fix that link to point to the appropriate specific page. |
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http://www.wacklepedia.com/s/se/semaphore.html
(66 words)
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| | [No title] |
| | If several tasks call GET_CONTROL at once, only one will be accepted, all other clients' requests will be queued FIFO CAVEATS: This is essentially the same as a binary semaphore. | | | 2000 languages; software costs soar! Military equipment contains embedded computers These computers cannot run traditional operating systems These computers must be programmed bare — wee need speed! | | | Ada is different: Parallel programming tools are part of the language High level rendezvous protocol replaces semaphore primitives One can program a bare machine using this high-level language PARALLELISM IN Ada: The execution of an Ada program consists of the execution of one or more tasks. |
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http://www.cosc.brocku.ca/Offerings/3P93/notes/tasking.doc
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| | Semaphore Programming Assignment |
| | Then do an animation of it as a separate program. | | | First, take your original program and run it with command line parameters that show starvation occuring. | | | Then modify your program to prevent starvation and re-run it with the same parameters that gave starvation before. |
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http://elvis.rowan.edu/~hartley/ConcProgJava/Labs/baboonsNoStarve.html
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| | Linux Magazine - April 2001 Compile Time More ConcurrentProgramming Topics |
| | Hopefully, this discussion will further your perception of locks and how they are used in concurrent programming. | | | In this month's column, we'll look at two types of concurrent programming techniques used to synchronize the execution of code in threads. | | | In the past two months we've introduced threads and mutexes, the locking mechanism used to prevent race conditions in threaded applications. |
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http://www.linux-mag.com/2001-04/compile_01.html
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