Chapter 5 Research
As mentioned (repeatedly) in class last week, this is a change in the assignments. Instead of print the exercises, each student should post a well-researched and succinct comment to these research blogs. The blogs are by chapter.
For this chapter, you should research the problme of livelock in a networked environment. Describe how it differs from deadlock and give an example of the problem. Identify at least two different methods the operating system could use to detect and resolve livelock.
For your comment, summarize your findings; include at least one relevant URL; and remember to use your full name in the comment.
Blog on!
10 Comments:
In the book Livelock is described when processes or jobs comepete for the same resources and the system stops responding causing neither job to move forward. Deadlock is described as a traffic jam, indefinate postponement or starvation of more the one job.
Most OS use interrupts to schedule the performance of task related to I/O events, which allows the CPU to spend most of its time doing useful processing.
RDAckerson
http://www.accessmylibrary.com/article-1G1-20553663/eliminating-receive-livelock-interrupt.html
Livelock in a networked evironment has been scarsly researched according to three University of Cambridge professors, due to the confusion of the term. Regardless, the mutual understanding between deadlock and live lock is that a system is at a standstill if no forward
progress is being made.
Forward
progress is the ability to acquire the lock, and
the lack of forward progress is deadlock. Livelock is similar to a deadlock, except that the states of the processes involved in the livelock constantly change with regard to one another, none progressing.
If the value of the counter equals a threshold value in the current clock cycle, then a livelock condition may be detected.
http://en.wikipedia.org/wiki/Deadlock#Livelock
http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-633.pdf
Livelock is a condition that occurs when two or more processes continually change their state in response to changes in the other processes.The result is that none of the processes will be completed.
The differance between deadlock and liveloce is that with deadlock nothing moves, everything comes to a complete stop. But with livelock processes are moving, but not progressing, they adapt to each other.
A human example of live lock would be two people who meet face-to-face in a corridor and each moves aside to let the other pass, but they end up moving from side to side without making any progress because they always move the same way at the same time and never cross each other.
A human example of deadlock would be two people drawing a graph. There is one pencil and one ruler between the both of them. One takes a pencil and the other takes a ruler. Neither one can complete their job because one is waiting for the ruler and the other is waiting for the ruler.
A few ways you might be able to resolve this problem are :Vary the time consumption of different threads by giving them differing amounts of input, or running them on hardware that varies in speed or run a large number of threads concurrently.
http://codingarchitect.wordpress.com/2006/01/18/multi-threading-basics-deadlocks-livelocks-and-starvation/
Susan Cain
Deadlock and livelock can happen at many different levels in a distributed system.If an operating system kernel spends all of its time servicing interrupts then user processes will starve. Deadlock is The event is usually the release of a resource protected by a lock, and therefore deadlock reduces to the inability to acquire a lock. http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-633.pdf
Gregory Wagner
Livelock is a condition that occurs when two or more processes continually change their state in response to changes in the other processes.The result is that none of the processes will be completed.
The difference between deadlock and livelock is that with deadlock nothing moves, everything comes to a complete stop. But with livelock processes are moving, but not progressing, they adapt to each other.
http://en.wikipedia.org/wiki/Deadlock
Livelock is a condition that occurs when two or more processes continually change their state in response to changes in the other processes.The result is that none of the processes will be completed.
An example of livelock is 2 cars comming at each other each car going form one lane to the other at the same time trying to get past but they cant because the other car is blocking the way. Deadlock example is 2 men trying to get into a rental car when there is only on car to take. A Way to solve this is by running them on hardware that varies in speed or run a large number of threads concurrently.
http://en.wikipedia.org/wiki/Deadlock
Rafael Riera
A condition that occurs when two processes are each waiting for the other to complete before proceeding. The result is that both processes hang. Deadlocks occur most commonly in multitasking and client/server environments. Ideally, the programs that are deadlocked, or the operating system, should resolve the deadlock, but this doesn't always happen.
If more than one process takes action, the deadlock detection algorithm can be repeatedly triggered. This can be avoided by ensuring that only one process (chosen randomly or by priority) takes action.
http://www.webopedia.com/TERM/D/deadlock.html
Shaleasa Osborne
Sam said livelock occur when everything is processing but nothing is being accomlihed on the otherhand deadlock noting is happening and the job is not processing niether one is benificial doing operations
A livelock is a condition that occurs when two or more processes continually change their state in response to changes in the other processes. The result is that none of the processes will complete. An analogy is when two people meet in a hallway and each tries to step around the other but they end up swaying from side to side getting in each other's way as they try to get out of the way. A deadlock on the other hand is a condition that occurs when two processes are each waiting for the other to complete before proceeding. The result is that both processes hang. Deadlocks occur most commonly in multitasking and client/server environments. Ideally, the programs that are deadlocked, or the operating system, should resolve the deadlock, but this doesn't always happen.
http://www.webopedia.com/TERM/L/livelock.html
http://www.webopedia.com/TERM/D/deadlock.html
Lourdjean Go
Livelock is that state of the processes involved constantly changing with regard to one another but not progressing, while Deadlock is when two or more competing actions are waiting for each other to finish thus ensuring that neither ever does. A example of livelock would be two drivers at an intersection waving each other on to go first.
http://en.wikipedia.org/wiki/Deadlock#Livelock
Ben Ayers
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