thr_continue(3scl)thr_continue(3scl)NAMEthr_continue - Continues execution of a suspended thread.
LIBRARY
SCL Threads Library (libthread.so)
SYNOPSIS
#include <thread.h>
int thr_continue(
thread_t target_thread );
PARAMETERS
Identifier of the thread to be resumed.
DESCRIPTION
This routine causes the specified target_thread to continue its execu‐
tion. If the thread was suspended, then the thread resumes its execu‐
tion. If the thread was not suspended, then this call has no effect.
SCL IMPLEMENTATION NOTES
POSIX threads does not support suspending and continueing a thread's
execution. Thus thr_continue(3scl) is implemented by sending a signal
to the target thread by calling pthread_kill(3).
The SCL thread library maintains state information for each thread to
ensure that only non-suspended threads are sent the suspend signal, and
that only suspended threads are sent the continue signal. This avoids
the potential problem of a thread having both suspend & continue sig‐
nals pending, where the order of the signals is indeterminate. The
receipt of the continue-signal causes the suspended thread to return
from the signal-handler for the suspend signal, and thus resume execu‐
tion.
thr_continue(3scl) does not return until it receives acknowledgement
from the suspended thread that it has received the continue signal.
Solaris does not require nor document this behaviour: it is done to
ensure the thread state information maintained within SCL is correct.
By default SCL uses the SIGUSR1 signal for thr_suspend(3scl), and
SIGUSR2 for thr_continue(3scl). However, these signals may be used by
applications for their own purposes, and so SCL enables the user to
specify alternate signals to be used for thr_suspend(3scl) and thr_con‐
tinue(3scl). This is achieved by setting the environment variables
STL_SIG_SUSPEND and STL_SIG_CONTINUE to the integer values of alterna‐
tive signals before running the application program. The signals and
their values are listed in the man-page for signal(4), and in the file
/usr/include/signal.h.
E.g. to use SIGXFSZ as the continue signal, where SIGXFSZ is defined as
value 25 in /usr/include/signal.h, issue a command like:
csh> setenv STL_SIG_CONTINUE 25
RETURN VALUES
If an error condition occurs, this routine returns an integer value
indicating the type of error.
Additional error return information may be written to the SCL error
log. Refer to scl_error_log(4scl) for details.
Possible return values are as follows: Successful completion. tar‐
get_thread specifies a non-existant thread ID. target_thread has ter‐
minated and thr_join(3scl) must be called on it to reclaim its
resources.
ERRORS
None.
RELATED INFORMATION
Functions: pthread_kill(3), scl_intro(3scl), scl_thread_intro(3scl),
thr_create(3scl), thr_suspend(3scl)
Files: scl_error_log(4scl), signal(4)
Manuals: Solaris Compatibility Libraries User's Guide
thr_continue(3scl)
