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If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner] .TH pthread_create 3C "23 Mar 2005" "SunOS 5.11" "Standard C Library Functions" .SH NAME pthread_create \- create a thread .SH SYNOPSIS .LP .nf cc -mt [ \fIflag\fR... ] \fIfile\fR... -lpthread [ \fIlibrary\fR... ] #include \fBint\fR \fBpthread_create\fR(\fBpthread_t *restrict\fR \fIthread\fR, \fBconst pthread_attr_t *restrict\fR \fIattr\fR, \fBvoid *(*\fR\fIstart_routine\fR)(void*), \fBvoid *restrict\fR \fIarg\fR); .fi .SH DESCRIPTION .sp .LP The \fBpthread_create()\fR function is used to create a new thread, with attributes specified by \fIattr\fR, within a process. If \fIattr\fR is \fINULL,\fR the default attributes are used. (See \fBpthread_attr_init\fR(3C)). If the attributes specified by \fIattr\fR are modified later, the thread's attributes are not affected. Upon successful completion, \fBpthread_create()\fR stores the \fBID\fR of the created thread in the location referenced by \fIthread\fR. .sp .LP The thread is created executing \fIstart_routine\fR with \fIarg\fR as its sole argument. If the \fIstart_routine\fR returns, the effect is as if there was an implicit call to \fBpthread_exit()\fR using the return value of \fIstart_routine\fR as the exit status. Note that the thread in which \fBmain()\fR was originally invoked differs from this. When it returns from \fBmain()\fR, the effect is as if there was an implicit call to \fBexit()\fR using the return value of \fBmain()\fR as the exit status. .sp .LP The signal state of the new thread is initialised as follows: .RS +4 .TP .ie t \(bu .el o The signal mask is inherited from the creating thread. .RE .RS +4 .TP .ie t \(bu .el o The set of signals pending for the new thread is empty. .RE .sp .LP Default thread creation: .sp .in +2 .nf pthread_t tid; void *start_func(void *), *arg; pthread_create(&tid, NULL, start_func, arg); .fi .in -2 .sp .LP This would have the same effect as: .sp .in +2 .nf \fBpthread_attr_t attr; pthread_attr_init(&attr); /* initialize attr with default */ /* attributes */ pthread_create(&tid, &attr, start_func, arg);\fR .fi .in -2 .sp .LP User-defined thread creation: To create a thread that is scheduled on a system-wide basis, use: .sp .in +2 .nf pthread_attr_init(&attr); /* initialize attr with default */ /* attributes */ pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM); /* system-wide contention */ pthread_create(&tid, &attr, start_func, arg); .fi .in -2 .sp .LP To customize the attributes for POSIX threads, see \fBpthread_attr_init\fR(3C). .sp .LP A new thread created with \fBpthread_create()\fR uses the stack specified by the \fIstackaddr\fR attribute, and the stack continues for the number of bytes specified by the \fIstacksize\fR attribute. By default, the stack size is 1 megabyte for 32-bit processes and 2 megabyte for 64-bit processes (see \fBpthread_attr_setstacksize\fR(3C)). If the default is used for both the \fIstackaddr\fR and \fIstacksize\fR attributes, \fBpthread_create()\fR creates a stack for the new thread with at least 1 megabyte for 32-bit processes and 2 megabyte for 64-bit processes. (For customizing stack sizes, see \fBNOTES\fR). .sp .LP If \fBpthread_create()\fR fails, no new thread is created and the contents of the location referenced by \fIthread\fR are undefined. .SH RETURN VALUES .sp .LP If successful, the \fBpthread_create()\fR function returns \fB0\fR. Otherwise, an error number is returned to indicate the error. .SH ERRORS .sp .LP The \fBpthread_create()\fR function will fail if: .sp .ne 2 .mk .na \fB\fBEAGAIN\fR\fR .ad .RS 10n .rt The system lacked the necessary resources to create another thread, or the system-imposed limit on the total number of threads in a process \fBPTHREAD_THREADS_MAX\fR would be exceeded. .RE .sp .ne 2 .mk .na \fB\fBEINVAL\fR\fR .ad .RS 10n .rt The value specified by \fIattr\fR is invalid. .RE .sp .ne 2 .mk .na \fB\fBEPERM\fR\fR .ad .RS 10n .rt The caller does not have appropriate permission to set the required scheduling parameters or scheduling policy. .RE .SH EXAMPLES .LP \fBExample 1 \fRExample of concurrency with multithreading .sp .LP The following is an example of concurrency with multithreading. Since POSIX threads and Solaris threads are fully compatible even within the same process, this example uses \fBpthread_create()\fR if you execute \fBa.out 0\fR, or \fBthr_create()\fR if you execute \fBa.out 1\fR. .sp .LP Five threads are created that simultaneously perform a time-consuming function, \fBsleep(\fR10\fB)\fR. If the execution of this process is timed, the results will show that all five individual calls to sleep for ten-seconds completed in about ten seconds, even on a uniprocessor. If a single-threaded process calls \fBsleep(\fR10\fB)\fR five times, the execution time will be about 50-seconds. .sp .LP The command-line to time this process is: .sp .ne 2 .mk .na \fBPOSIX threading\fR .ad .RS 21n .rt /usr/bin/time a.out 0 .RE .sp .ne 2 .mk .na \fBSolaris threading\fR .ad .RS 21n .rt /usr/bin/time a.out 1 .RE .sp .in +2 .nf /* cc thisfile.c -lthread -lpthread */ #define _REENTRANT /* basic 3-lines for threads */ #include #include #define NUM_THREADS 5 #define SLEEP_TIME 10 void *sleeping(void *); /* thread routine */ int i; thread_t tid[NUM_THREADS]; /* array of thread IDs */ int main(int argc, char *argv[]) { if (argc == 1) { printf("use 0 as arg1 to use pthread_create(\|)\en"); printf("or use 1 as arg1 to use thr_create(\|)\en"); return (1); } switch (*argv[1]) { case '0': /* POSIX */ for ( i = 0; i < NUM_THREADS; i++) pthread_create(&tid[i], NULL, sleeping, (void *)SLEEP_TIME); for ( i = 0; i < NUM_THREADS; i++) pthread_join(tid[i], NULL); break; case '1': /* Solaris */ for ( i = 0; i < NUM_THREADS; i++) thr_create(NULL, 0, sleeping, (void *)SLEEP_TIME, 0, &tid[i]); while (thr_join(0, NULL, NULL) == 0) ; break; } /* switch */ printf("main(\|) reporting that all %d threads have terminated\en", i); return (0); } /* main */ void * sleeping(void *arg) { int sleep_time = (int)arg; printf("thread %d sleeping %d seconds ...\en", thr_self(\|), sleep_time); sleep(sleep_time); printf("\enthread %d awakening\en", thr_self(\|)); return (NULL); } .fi .in -2 .sp .LP If \fBmain()\fR had not waited for the completion of the other threads (using \fBpthread_join\fR(3C) or \fBthr_join\fR(3C)), it would have continued to process concurrently until it reached the end of its routine and the entire process would have exited prematurely. See \fBexit\fR(2). .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 _ Interface StabilityStandard _ MT-LevelMT-Safe .TE .SH SEE ALSO .sp .LP \fBfork\fR(2), \fBpthread_attr_init\fR(3C), \fBpthread_cancel\fR(3C), \fBpthread_exit\fR(3C), \fBpthread_join\fR(3C), \fBsysconf\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5) .SH NOTES .sp .LP Multithreaded application threads execute independently of each other, so their relative behavior is unpredictable. Therefore, it is possible for the thread executing \fBmain()\fR to finish before all other user application threads. The \fBpthread_join\fR(3C)function, on the other hand, must specify the terminating thread (IDs) for which it will wait. .sp .LP A user-specified stack size must be greater than the value \fBPTHREAD_STACK_MIN\fR. A minimum stack size may not accommodate the stack frame for the user thread function \fIstart_func\fR. If a stack size is specified, it must accommodate \fIstart_func\fR requirements and the functions that it may call in turn, in addition to the minimum requirement. .sp .LP It is usually very difficult to determine the runtime stack requirements for a thread. \fBPTHREAD_STACK_MIN\fR specifies how much stack storage is required to execute a \fINULL\fR \fIstart_func\fR. The total runtime requirements for stack storage are dependent on the storage required to do runtime linking, the amount of storage required by library runtimes (as \fBprintf()\fR) that your thread calls. Since these storage parameters are not known before the program runs, it is best to use default stacks. If you know your runtime requirements or decide to use stacks that are larger than the default, then it makes sense to specify your own stacks.