Mixed

What happens when you call a fork () in a thread?

What happens when you call a fork () in a thread?

When the parent calls fork, the entire process is frozen for a moment, atomically duplicated, and then the parent is unfrozen as a whole, yet in the child only the one thread that called fork is unfrozen, everything else stays frozen.

What is the difference between fork () and exec ()?

fork starts a new process which is a copy of the one that calls it, while exec replaces the current process image with another (different) one. Both parent and child processes are executed simultaneously in case of fork() while Control never returns to the original program unless there is an exec() error.

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What is the use of fork and exec system calls?

The fork() and exec() are the system calls that are used for controlling processes. Both are used to create a new process where the process is the program in execution. The fork() system call when invoked by any process creates a new duplicate child process of the invoking process.

What are the major threading issues?

Multithreaded programs allow the execution of multiple parts of a program at the same time. Difficult to Identify Errors− Identification and correction of errors is much more difficult in multithreaded processes as compared to single threaded processes. …

How fork () and exec () system calls behave in multithreaded environment along with other threading issues?

The fork() system call is used to create a separate, duplicate process. The semantics of the fork() and exec() system calls change in a multithreaded program. If a thread invokes the exec() system call, the program specified in the parameter to exec() will replace the entire process — including all threads.

Which exec call is a system call?

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The exec type system calls allow a process to run any program files, which include a binary executable or a shell script . Syntax: int execvp (const char *file, char *const argv[]); file: points to the file name associated with the file being executed.

How does exec system call work?

The exec system call is used to execute a file which is residing in an active process. When exec is called the previous executable file is replaced and new file is executed. More precisely, we can say that using exec system call will replace the old file or program from the process with a new file or program.

What is the use of exec system calls?

What happens if exec() system call comes after Fork()?

Here the issue is if the exec () system call is lined up just after the fork () system call then duplicating all the threads of parent process in the child process by fork () is useless. As the exec () system call will replace the entire process with the process provided to exec () in the parameter.

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What is fork() in Unix?

Well, there are two versions of fork () in some of the UNIX systems. Either the fork () can duplicate all the threads of the parent process in the child process or the fork () would only duplicate that thread from parent process that has invoked it.

Which version of fork() must be used for duplicate threads?

Either the fork () can duplicate all the threads of the parent process in the child process or the fork () would only duplicate that thread from parent process that has invoked it. Which version of fork () must be used totally depends upon the application.

What happens when Fork is called from a process?

The fork () call creates a duplicate process of the process that invokes fork (). The new duplicate process is called child process and process invoking the fork () is called the parent process. Both the parent process and the child process continue their execution from the instruction that is just after the fork ().