thr_suspend(3C) Standard C Library Functions thr_suspend(3C)NAME
thr_suspend, thr_continue - suspend or continue thread execution
SYNOPSIS
cc -mt [ flag... ] file...[ library... ]
#include <thread.h>
int thr_suspend(thread_t target_thread);
int thr_continue(thread_t target_thread);
DESCRIPTION
The thr_suspend() function immediately suspends the execution of the
thread specified by target_thread. On successful return from thr_sus‐
pend(), the suspended thread is no longer executing. Once a thread is
suspended, subsequent calls to thr_suspend() have no effect.
The thr_continue() function resumes the execution of a suspended
thread. Once a suspended thread is continued, subsequent calls to
thr_continue() have no effect.
A suspended thread will not be awakened by any mechanism other than a
call to thr_continue(). Signals and the effect of calls tomu‐
tex_unlock(3C), rw_unlock(3C), sema_post(3C), cond_signal(3C), and
cond_broadcast(3C) remain pending until the execution of the thread is
resumed by thr_continue().
RETURN VALUES
If successful, the thr_suspend() and thr_continue() functions return
0. Otherwise, a non-zero value is returned to indicate the error.
ERRORS
The thr_suspend() and thr_continue() functions will fail if:
ESRCH The target_thread cannot be found in the current
process.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOthr_create(3C), thr_join(3C), attributes(5), standards(5)WARNINGS
The thr_suspend() function is extremely difficult to use safely because
it suspends the target thread with no concern for the target thread's
state. The target thread could be holding locks, waiting for a lock, or
waiting on a condition variable when it is unconditionally suspended.
The thread will not run until thr_continue() is applied, regardless of
any calls to mutex_unlock(), cond_signal(), or cond_broadcast() by
other threads. Its existence on a sleep queue can interfere with the
waking up of other threads that are on the same sleep queue.
The thr_suspend() and thr_continue() functions should be avoided. Mech‐
anisms that involve the cooperation of the targeted thread, such as
mutex locks and condition variables, should be employed instead.
SunOS 5.10 22 Mar 2002 thr_suspend(3C)
