'\" te
.\"  Copyright (c) 2001 Sun Microsystems, Inc.  All Rights Reserved
.TH thr_suspend 3C "22 Mar 2002" "SunOS 5.11" "Standard C Library Functions"
.SH NAME
thr_suspend, thr_continue \- suspend or continue thread execution
.SH SYNOPSIS
.LP
.nf
cc -mt [ \fIflag\fR... ] \fIfile\fR...[ \fIlibrary\fR... ]
#include <thread.h> 

\fBint\fR \fBthr_suspend\fR(\fBthread_t\fR \fItarget_thread\fR);
.fi

.LP
.nf
\fBint\fR \fBthr_continue\fR(\fBthread_t\fR \fItarget_thread\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBthr_suspend()\fR function immediately suspends the execution of the thread specified by \fItarget_thread\fR. On successful return from \fBthr_suspend()\fR, the suspended thread is no longer executing. Once a thread is suspended, subsequent calls to \fBthr_suspend()\fR have no effect.
.sp
.LP
The \fBthr_continue()\fR function resumes the execution of a suspended thread. Once a suspended thread is continued, subsequent calls to \fBthr_continue()\fR have no effect.
.sp
.LP
A suspended thread will not be awakened by any mechanism other than a call to \fBthr_continue()\fR.  Signals and the effect of calls to\fBmutex_unlock\fR(3C), \fBrw_unlock\fR(3C), \fBsema_post\fR(3C), \fBcond_signal\fR(3C), and \fBcond_broadcast\fR(3C) remain pending until the execution of the thread is resumed by \fBthr_continue()\fR.
.SH RETURN VALUES
.sp
.LP
If successful, the \fBthr_suspend()\fR and \fBthr_continue()\fR functions return  \fB0\fR. Otherwise, a non-zero value is returned to indicate the error.
.SH ERRORS
.sp
.LP
The \fBthr_suspend()\fR and \fBthr_continue()\fR functions will fail if:
.sp
.ne 2
.mk
.na
\fB\fBESRCH\fR \fR
.ad
.RS 10n
.rt  
The \fItarget_thread\fR cannot be found in the current process.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
MT-LevelMT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBthr_create\fR(3C), \fBthr_join\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5) 
.SH WARNINGS
.sp
.LP
The \fBthr_suspend()\fR 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 \fBthr_continue()\fR is applied, regardless of any calls to \fBmutex_unlock()\fR, \fBcond_signal()\fR, or \fBcond_broadcast()\fR 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.
.sp
.LP
The \fBthr_suspend()\fR and \fBthr_continue()\fR functions should be avoided. Mechanisms that involve the cooperation of the targeted thread, such as mutex locks and condition variables, should be employed instead.