_lwp_create - create a new light-weight process
int _lwp_create(ucontext_t *contextp, uint_t flags, lwpid_t
The _lwp_create() function adds a lightweight process (LWP)
to the current process. The contextp argument specifies the
initial signal mask, stack, and machine context (including
the program counter and stack pointer) for the new LWP. The
new LWP inherits the scheduling class and priority of the
If _lwp_create() is successful and new_lwp is not NULL, the
ID of the new LWP is stored in the location pointed to by
The flags argument specifies additional attributes for the
new LWP. The value in flags is constructed by the bitwise
inclusive OR operation of the following values:
The LWP is created detached.
The LWP is created as a daemon LWP.
The LWP is created suspended.
If LWP_DETACHED or LWP_DAEMON is specified, then the LWP is
created in the detached state. Otherwise the LWP is created
in the undetached state. The ID (and system resources) asso-
ciated with a detached LWP can be automatically reclaimed
when the LWP exits. The ID of an undetached LWP cannot be
reclaimed until it exits and another LWP has reported its
termination by way of _lwp_wait(2). This allows the waiting
LWP to determine that the waited for LWP has terminated and
to reclaim any process resources that it was using.
If LWP_DAEMON is specified, then in addition to being
created in the detached state, the LWP is created as a dae-
mon LWP. Daemon LWPs do not interfere with the exit condi-
tions for a process. A process will exit as though _exit(0)
had been called when the last non-daemon LWP calls
_lwp_exit() (see exit(2) and _lwp_exit(2)). Also, an LWP
that is waiting in _lwp_wait(2) for any LWP to terminate
will return EDEADLK when all remaining LWPs in the process
are either daemon LWPs or other LWPs waiting in _lwp_wait().
If LWP_SUSPENDED is specified, then the LWP is created in a
suspended state. This allows the creator to change the LWP's
inherited attributes before it starts to execute. The
suspended LWP can only be resumed by way of
_lwp_continue(2). If LWP_SUSPENDED is not specified the LWP
can begin to run immediately after it has been created.
Upon successful completion, 0 is returned. A non-zero value
indicates an error.
If any of the following conditions are detected,
_lwp_create() fails and returns the corresponding value:
Either the context parameter or the new_lwp parameter
point to invalid addresses.
A system limit is exceeded, (for example, too many
LWPs were created for this real user ID).
The flags argument contains values other than those
Example 1: How a stack is allocated to a new LWP.
This example shows how a stack is allocated to a new LWP.
The _lwp_makecontext() function is used to set up the con-
text parameter so that the new LWP begins executing a func-
contextp = (ucontext_t *)malloc(sizeof(ucontext_t));
stackbase = malloc(stacksize);
_lwp_makecontext(contextp, func, arg, private, stackbase, stacksize);
sigprocmask(SIGSETMASK, NULL, &contextp->uc_sigmask);
error = _lwp_create(contextp, NULL, &new_lwp);
Applications should use bound threads rather than the _lwp_*
functions (see thr_create(3THR)). Using LWPs directly is
not advised because libraries are only safe to use with
threads, not LWPs.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Interface Stability | Obsolete |
| MT-Level | Async-Signal-Safe |
_lwp_cond_timedwait(2), _lwp_continue(2), _lwp_detach(2),
_lwp_exit(2), _lwp_makecontext(2), _lwp_wait(2), alarm(2),
exit(2), poll(2), signal(3HEAD), sleep(3C),
thr_create(3THR), ucontext(3HEAD), attributes(5)
The _lwp_create() function is obsolete and will be removed
in a future release.
Man(1) output converted with