Question: What is wait in operating system?

In computer operating systems, a process (or task) may wait on another process to complete its execution. … The parent process may then issue a wait system call, which suspends the execution of the parent process while the child executes.

What does wait () do?

The wait() function will suspend execution of the calling thread until status information for one of its terminated child processes is available, or until delivery of a signal whose action is either to execute a signal-catching function or to terminate the process.

How does wait work?

The wait() system call suspends execution of the current process until one of its children terminates. The call wait(&status) is equivalent to: waitpid(-1, &status, 0); The waitpid() system call suspends execution of the current process until a child specified by pid argument has changed state.

What is difference between wait and Waitpid?

The wait function can block the caller until a child process terminates, whereas waitpid has an option that prevents it from blocking. The waitpid function doesn’t wait for the child that terminates first; it has a number of options that control which process it waits for.

What is meant by system call?

In computing, a system call (commonly abbreviated to syscall) is the programmatic way in which a computer program requests a service from the kernel of the operating system on which it is executed. … System calls provide an essential interface between a process and the operating system.

What is Pid_t?

pid_t data type stands for process identification and it is used to represent process ids. Whenever, we want to declare a variable that is going to be deal with the process ids we can use pid_t data type. The type of pid_t data is a signed integer type (signed int or we can say int).

How does Waitpid work?

If pid is greater than 0, waitpid() waits for termination of the specific child whose process ID is equal to pid. If pid is equal to zero, waitpid() waits for termination of any child whose process group ID is equal to that of the caller.

What is sleep () in C?

The function sleep gives a simple way to make the program wait for a short interval. … The sleep function waits for seconds seconds or until a signal is delivered, whichever happens first. If sleep returns because the requested interval is over, it returns a value of zero.

What is Wexitstatus?

This macro queries the child termination status provided by the wait and waitpid functions. If the WIFEXITED macro indicates that the child process exited normally, the WEXITSTATUS macro returns the exit code specified by the child process.

What does wait Null?

1 Answer. wait(NULL) will block parent process until any of its children has finished. If child terminates before parent process reaches wait(NULL) then the child process turns to a zombie process until its parent waits on it and its released from memory.

What happens when a process terminates but its parent does not wait for it?

Zombie process is that process which has terminated but whose process control block has not been cleaned up from main memory because the parent process was not waiting for the child.

What is wait () in Java?

Simply put, wait() is an instance method that’s used for thread synchronization. It can be called on any object, as it’s defined right on java. lang. Object, but it can only be called from a synchronized block. It releases the lock on the object so that another thread can jump in and acquire a lock.

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