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Topic: Mutual exclusion


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In the News (Mon 22 Apr 19)

  
  ONJava.com -- Implementing Mutual Exclusion for AJAX
The portions of code that access these shared data structures are known as critical sections, and the practice of only letting one run at a time is known as mutual exclusion.
So, a mutual exclusion mechanism is needed to ensure that only one critical section will start and finish before another is started.
Of the several mutual exclusion algorithms in the computer science literature, one known as Lamport's bakery algorithm works for multiple competing threads of control when the only communication between them is shared memory (i.e., no special mechanisms like semaphores, atomic set-and-test, etc. are required).
www.onjava.com /pub/a/onjava/2006/04/05/ajax-mutual-exclusion.html?CMP=OTC-FP2116136014&ATT=Implementing+Mutual+Exclusion+for+AJAX   (683 words)

  
  Mutual exclusion - Wikipedia, the free encyclopedia
Mutual exclusion (often abbreviated to mutex) algorithms are used in concurrent programming to avoid the simultaneous use of un-shareable resources by pieces of computer code called critical sections.
On a uniprocessor system the common way to achieve mutual exclusion is to disable interrupts for the smallest possible number of instructions that will prevent corruption of the shared data structure, the so-called "critical region".
Most classical mutual exclusion methods attempt to reduce latency and busy-waits by using queuing and context switches.
en.wikipedia.org /wiki/Mutual_exclusion   (534 words)

  
 Windows Media Format 11 SDK Mutual Exclusion
Mutual exclusion is a feature of the Windows Media Format SDK that enables you to specify a number of mutually exclusive streams that all equate to the same output.
Mutual exclusion is defined in the profile used to create a file.
For all types of mutual exclusion except MBR and language-based mutual exclusion, the reader always selects the default stream, which is the first stream added to the mutual exclusion object in the profile.
msdn.microsoft.com /library/en-us/wmform11/htm/mutualexclusion.asp   (810 words)

  
 [No title]   (Site not responding. Last check: 2007-10-30)
Mutual exclusion ensures that concurrent access of processes to a shared resource or data is serialized, that is, executed in mutually exclusive manner.
In mutual exclusion algorithms, the fairness property generally means the CS execution requests are executed in the order of their arrival (time is determined by a logical clock) in the system.
The mutual exclusion algorithm is independent of the underlying topology of the network and there is no need for a multicast facility with in the network, however such facility will improve the performance of the algorithm.
www.cs.engr.uky.edu /~singhal/CH-Mutual-Exclusion.txt   (6485 words)

  
 Windows Media Format 11 SDK Mutual Exclusion Object
A mutual exclusion object is used to specify a number of streams, of which only one can be delivered at a time.
Mutual exclusion is an optional part of a profile.
Mutual exclusion objects can be created for existing mutual exclusion information in a profile or can be created empty, ready to receive new data.
msdn.microsoft.com /library/en-us/WMFORM11/htm/mutualexclusionobjects.asp   (262 words)

  
 MutualExclusion - PineWiki
Note that the protocol is not required to guarantee that processes leave the critical or remainder state, but we generally have to insist that the processes at least leave the critical state on their own to make progress.
Mutual exclusion is a safety property (see IOAutomata) so we expect to prove it using invariants.
Intuition for mutual exclusion is that if you have a lower number than I do, then I block waiting for you, for lockout-freedom is eventually I have the smallest number.
pine.cs.yale.edu /pinewiki/MutualExclusion   (1853 words)

  
 Read-Copy Update Mutual Exclusion for Linux
Various mechanisms for mutual exclusion have been used in traditional Unix kernels including spin locks, semaphores, reader-writer spin locks etc. Even uniprocessor systems require controlled concurrency when critical section code can be executed from both process as well interrupt context.
While short-term mutual exclusions like spin locks are simple to use, with the advent of faster cpus and memory interconnect speeds not keeping up with it, cost of acquiring spinning locks is increasing with each generation of architecture.
Read-Copy Update is one such mutual exclusion method where readers (threads trying to access, but not modify the data) can access the shared data without acquiring any conventional lock.
lse.sourceforge.net /locking/rcupdate.html   (1179 words)

  
 Dr. Dobb's | Mutual Exclusion and Synchronization in Java | July 22, 2001
Mutual exclusion for primitive types might be necessary.
This is a more general case of exclusion, where the number of concurrent users may be greater than one but limited to a specific maximum.
A mutex (short for mutual exclusion) is an object used to gate exclusive access to a shared resource; see Listing Six.
www.ddj.com /184410467   (3581 words)

  
 Mutual exclusion algorithm discovery
The mutual exclusion problem was formally defined by Edsger Dijkstra in 1965.
Although many new interesting algorithms have been found, we think the main contribution of this work is in demonstrating that the approach suggested for automatic discovery of (correct) synchronization algorithms is feasible.
In a sense, the distinction is the same as between a high-level programming language used by humans, and the assembly language used by the hardware.
bardavid.com /mead   (673 words)

  
 CIS 307: Mutual Exclusion and Elections in Distributed Systems
Pn that want to use in mutual exclusion a resource R. The requirements of mutual exclusion, progress, fairness, etc. apply now as they did when we were in a shared memory system.
We now consider the problem of mutual exclusion in the fully distributed case where there is no Manager.
This algorithm, due to Ricart-Agrawala has been extended by Raymond to the case where more that 1 process can be in the critical region at one time and to the case where requests are for multiple copies of a resource.
www.cis.temple.edu /~ingargio/old/cis307s00/readings/mutual.html   (1216 words)

  
 mutual exclusion - ResearchIndex document query
the mutual exclusion property of a real-time mutual exclusion protocol.
The use of these techniques for various mutual exclusion algorithms shows that they are promising.
as different from ab t ba, which represents mutual exclusion between a and b.
citeseer.ist.psu.edu /cis?q=mutual+exclusion   (627 words)

  
 mutual exclusion.   (Site not responding. Last check: 2007-10-30)
Mutual exclusion appends when 2 or more memory lines are needed but cannot be in cache all-together because they fit in the same cache line and successive access cause exclusion of the memory lines previously loaded.
This is a real problem for direct mapped caches where a memory line can be in only one cache line.
Mutual exclusion can also appends for matrix operations like dgemm: when using a block method, leading dimension
www.linuxshowcase.org /2000/2000papers/papers/thomas/thomas_html/node11.html   (175 words)

  
 Beyond Simple Mutual Exclusion
However, on multiprocessor systems, mutual exclusion is an expensive operation, not only because of the overhead involved, but because one processor will sit idle while the other has access to the data.
When mutual exclusion is the only option, we are then faced with the potentially large delays incurred in the entry section, particularly in large distributed systems.
Leslie Lamport once again led the way with his ``fast'' mutual exclusion algorithm [8], which only required seven memory accesses in the event of no contention.
www.teamten.com /lawrence/242.paper/node4.html   (957 words)

  
 Mutual Exclusion
When resources are shared, but they must only be accessed by one process at a time, one has a mutual exclusion situation.
The output shows that reading and writing are mutually exclusive, they alternate and do not overlap.
Again, writing and reading are mutually exclusive, but several readers may read at the same time.
simpy.sourceforge.net /mutual_exclusion.htm   (587 words)

  
 Citations: Self-stabilizing mutual exclusion on directed graphs - Alstein, Hoepman, Olivier, van der Put (ResearchIndex)
To guarantee the presence of a token in the ring the smallest non divisor of n (n being the network size) snd(n) the magic number as it was de ned in [17] is used.
two mutual exclusion algorithms for directed arbitrary networks with identi ers requiring the preprocessing of a spanning tree.
Kakugawa and Yamashita present in [19] a self stabilizing token circulation protocol under unfair scheduler on rings.
citeseer.ist.psu.edu /context/682431/452951   (732 words)

  
 Mutual Exclusion for Critical Sections of Code
Thus, in an MP system, thread A executing on Processor 1 must not contend with thread B executing on Processor 2.
In a uniprocessor environment these contentions were easily dealt with: Mutual exclusion was implemented for two interrupt service routines or an interrupt service routine and a thread of control by raising
To ensure mutual exclusion between threads of control, no thread could be preempted while running in kernel mode.
docs.hp.com /en/5965-4643/ch01s05.html   (241 words)

  
 AJAX from Scratch: Implementing Mutual Exclusion in JavaScript
Although there are classic algorithms that implement mutual exclusion without requiring special support from the language or environment, even these expect some basics that are missing from JavaScript and browsers such as Internet Explorer.
By putting all the logic that should go into a critical section into a command object, along with all the data needed to initiate that logic, the Bakery algorithm can be reworked into a class that manages commands.
This mutual exclusion class will invoke critical sections (encapsulated as separate command object methods) only when other critical sections are not executing, as if each were in its own virtual thread.
www.developer.com /lang/jscript/article.php/3592016   (1409 words)

  
 Python Mutual Exclusion Class for Independent Python processes   (Site not responding. Last check: 2007-10-30)
Python Mutual Exclusion Class for Independent Python processes
This class can be used to enforce mutual exclusion over multiple independent Python processes.
To test the mutual exclusion run this application in several Xterms at the same time.
www.its.caltech.edu /~fvlingen/html/software/mutualExclusion/index.html   (47 words)

  
 mutual exclusion - OneLook Dictionary Search
We found 3 dictionaries with English definitions that include the word mutual exclusion:
Tip: Click on the first link on a line below to go directly to a page where "mutual exclusion" is defined.
mutual exclusion : Free On-line Dictionary of Computing [home, info]
www.onelook.com /?loc=rescb&w=mutual+exclusion   (81 words)

  
 Mutual Exclusion Petri Net
This Petri net shows how mutual exclusion (where two processes can not be in the same state) is modelled.
The Petri net browser supports the following functions:
Last updated May 11, 1998 by Robert Esser
www.cs.adelaide.edu.au /users/esser/mutual.html   (164 words)

  
 Mutual Exclusion - TechIMO Forums
I am Masters(Computer Science) student and am currently doing Thesis on Mutual Exclusion in Distributed Systems.
Although I like to participate in DC projects, I don't know much about the coding and work really behind it.
I took my Operating Systems class last semester and we got to talk about Mutual Exclusion, semaphors and all that stuff.!
www.techimo.com /forum/showthread.php?t=81398   (150 words)

  
 CIS 307: Mutual Exclusion and Critical Regions   (Site not responding. Last check: 2007-10-30)
Here we examine the kind of reasoning involved in achieving mutual exclusion by software means in a tightly-coupled computer system.
Global boolean array variable flag with two components both initialized to false; Process Pi, where i is 0 or 1, has local integer variable i with value 0 for P0 and 1 for P1; PROLOGUE: while flag[1-i] do null; flag[i] := true; EPILOGUE: flag[i] := false;
Solution 2 is a bad solution because it does not guaranty mutual exclusion.
joda.cis.temple.edu /~ingargio/old/cis307s95/readings/mutex.html   (707 words)

  
 Usage of Read-Copy Update Mutual-Exclusion Mechanism in Linux
However, readers must be excluded in those cases where writers cannot make their modifications in such a way that each intermediate state appears consistent to a reader.
This read-copy mechanism is unable to provide this form of exclusion.
Therefore, algorithms employing the RCU mechanism must tolerate stale data, or must explicitly flag stale data (see Pugh's skip-list papers for ways of accomplishing this).
lse.sourceforge.net /locking/rcu/rcupdate_doc.html   (7426 words)

  
 Semaphores For Mutual Exclusion   (Site not responding. Last check: 2007-10-30)
If the semaphore has already been signaled, however, when the process waits, it doesn't actually suspend, but just continues right on through.
Semaphores for mutual exclusion are a sub-category of all semaphores.
They are used to block access to a resource, usually.
c2.com /cgi/wiki?SemaphoresForMutualExclusion   (176 words)

  
 Onjava Article: 'Implementing Mutual Exclusion for AJAX'
In "Implementing Mutual Exclusion for AJAX," author Bruce Wallace offers a mutex implementation in JavaScript to handle concurrent access of DOM resources, a problem that's hard to reproduce and even harder to solve.
By encapsulating event handling logic into Command classes, not only can the Wallace variation be employed, but the stage is also set to provide rich undo/redo functionality, scripting interfaces, and unit test instrumentation.
Onjava Article: 'Implementing Mutual Exclusion for AJAX' by
www.theserverside.com /news/thread.tss?thread_id=39825   (1846 words)

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