Terminate and cause the zombie tasks to be deallocated

Assignment Help Computer Engineering
Reference no: EM1334170

When a child process is fork()ed, a parent may wait for the successful completion of the child via the wait() service (or one of its variants) so that the return result of that application can be read from the process descriptor block.

If the parent does not perform a wait() operation on the child process after it terminates, Unix will keep the process descriptor block active for this application in hopes that eventually the parent will wait() or that the parent will itself terminate.

If you perform the ps command in this scenario, you may find a number of "zombie" processes - these are processes marked with a Z in the output of ps that are children of a currently running parent that hasn't yet waited upon their completion. Normally, this isn't much of a problem, as eventually, the parent will terminate and cause the zombie tasks to be deallocated.

However, in a server application such as the email database server above, this becomes a problem, as the server generally never terminates, and as a result, the system list of process descriptor blocks becomes cluttered by zombies (processes that have properly terminated by haven't been waited upon by the parent).

To avoid this problem, Unix ensures that a terminating child application can send a signal to the parent indicating that it has terminated (SIG_CHILD). The parent should catch this signal, and issue a wait() or one of its variants to clean up the zombied process descriptor block.

For this question, describe the concept of a signal, and indicate how the parent application can be configured to act upon the SIG_CHILD signal from each child as they terminate to avoid the zombie issue.

In your answer, discuss the OS services that Unix provides to support signal processing.

Reference no: EM1334170

Questions Cloud

Explaining future values and present values : Find out the future value of $9,000 at the end of five periods at 8% compounded interest? Find out the present value of $9,000 due eight periods hence, discounted at 11%?
Taking decision regarding replacing looms : SMM has decided to replace one of its looms and has researched the following cost data on replacement looms.
Explain the pros and cons of this marketing idea : Explain the pros and cons of this marketing idea  proposed by the company from the both a financial and non-financial perspective.
Pros and cons of using technology : What do you see as being the pros and cons of using technology? Is it possible to rely too much on technology?
Terminate and cause the zombie tasks to be deallocated : while a child process is fork()ed, a parent may wait for the successful completion of the child via the wait() service (or one of its variants) so that the return result of that application can be read from the process descriptor block.
Treasury bond interest rates : Assume you own the 8% October 2008 treasury bond and it is expected that the market interest rate will increase from 8% to 9% in the next three months.
The processor save in fraction of its visits to keyboard : In an 8-hour interval, an operator controls systems with 60 commands on an average, entered through a keyboard.
Controlling the metadata : Does the Word version you are using provide any control over metadata, can you eliminate it, hide it, reduce it etc?
Determining subprime mortgage crisis : What are the risks which are associated with debt, and why may those risks be unacceptable to the corporation that needs money?

Reviews

Write a Review

 

Computer Engineering Questions & Answers

  Mutual authentication and key establishment protocol

Assume a server-assisted mutual authentication and key establishment protocol. Suppose that Alice and the Server share the pairwise symmetric key KAS; however Bob and Server share a pairwise symmetric key KBS.

  State how you would recover an actual set s

Prove accuracy of your greedy algorithm by stating and proving the loop invariant.State how you would recover an actual set S.

  Explaining dynamic programming approach

Assume we have a directed the acyclic graph G = (V,E) with the real-valued edge weights and two distinguished vertices s and t.

  Suppose that the toolbar is named tbrcurrent

at last if the index of the button is two (2), then call the procedure named ExitSolution. Assume that the toolbar is named tbrCurrent.

  Suppose poisson arrivals and departures at each router

A CPU in a router can process 2 million packets/sec. The load offered to it is 1.5 million packets/sec. If the route from source to destination contains 10 routers (having no additional traffic), how much time is spent being queued and serviced by..

  Why compression algorithms are frequently used in forensics

why Compression algorithms are frequently used in forensics.how they can potentially affect evidence, paying particular attention to algorithms implemented by forensic tools. You need to be clear yet concise.

  What are the kinds of information systems

What are the kinds of information systems

  Breaking the version of cipher

Assume an improved version of Vigen ere cipher in which in place of utilizing several shift ciphers, several mono-alphabetic substitution ciphers are utilized.Display how to break this version of the cipher.

  Recognizing the threats in the code

State two recent virus threats; whether they are minor or the major threats?

  Developing the function to list software installed on system

Write down a function which list the software (name and vendor) installed over the computer specified by the input argument. The function should output the list to screen and output the list to the CSV file.

  Express what is a keyword in a programming language

Why explantion of a variable is considered to be an important.

  Technology assumption and analyzing the system

Which businesses and services would no longer be required if the perfect technology assumption were a reality for automobile? Explain how does the perfect technology assumption help with analyzing the system?

Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd