Operating System [3i Infotech Placement]: Sample Questions 26 - 27 of 81

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Question 26

Operating System
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Describe in Detail

Essay▾

What is a zombie?

Explanation

  • Process that has completed execution but still retains entry in the process table.
  • At end of the process, every memory resource is deallocated and can be used by other processes, however, entry of the process remains unavailable.
  • When exit status of a child is read by the parent using the wait system call- zombie can be removed.
  • Ones the zombie is removed, the process id in the process table is removed and reused.
  • Zombie state finishes when the parent dies.
  • Zombie processes accumulate in the system when parent process is not programmed properly and never calls wait () -zombine children remain in the memory.

Question 27

Operating System

Question

MCQ▾

Which function is the entry point for a DLL in MS Windows

Choices

Choice (4)

a.

Main

b.

Dllmain

c.

Libmain

d.

Winmain

Answer

b.

Explanation

  • DllMain is a placeholder for a user-defined function which serves as entry point for DLL.
  • On creating a DLL, developer can optionally specify an entry point function.
  • The entry point function is called when processes or threads attach themselves to the DLL or detach themselves from the DLL.
  • Entry point function is used to initialize data structures or to destroy data structures as required by the DLL.
  • Additionally, for multithreaded applications, entry point can be used for initializing thread local storage- to allocate memory private to each thread.

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