PTHREAD_SUSPEND_NP(3) |
Library Functions Manual |
PTHREAD_SUSPEND_NP(3) |
NAME
pthread_suspend_np, pthread_resume_np — suspend/resume the given thread
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
SYNOPSIS
#include <pthread.h>
int
pthread_suspend_np(pthread_t thread);
int
pthread_resume_np(pthread_t thread);
DESCRIPTION
The
pthread_suspend_np() function suspends the
thread given as argument. If
thread is the currently running thread as returned by
pthread_self(3), the function fails and returns
EDEADLK. Otherwise, it removes the named thread from the running queue, and adds it to the suspended queue. The
thread will remain blocked until
pthread_resume_np() is called on it. In other words,
pthread_resume_np() resumes the
thread given as argument, if it was suspended.
RETURN VALUES
Both functions return 0 on success and an error number indicating the reason for the failure.
COMPATIBILITY
These functions are non-standard extensions.
ERRORS
The
pthread_suspend_np() function may fail if:
-
[EDEADLK]
-
The thread requested to suspend was the currently running thread.
-
[ESRCH]
-
The supplied thread was invalid.
The pthread_resume_np() function may fail if:
-
[ESRCH]
-
The supplied thread was invalid.
NOTES
Some
pthread_suspend_np() implementations may allow suspending the current thread. This is dangerous, because the semantics of the function would then require the scheduler to schedule another thread, causing a thread context switch. Since that context switch can happen in a signal handler by someone calling
pthread_suspend_np() in a signal handler, this is currently not allowed.
In pthread_resume_np() the NetBSD implementation does not check if the thread argument is not already suspended. Some implementations might return an error condition if pthread_resume_np() is called on a non-suspended thread.