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The lightweight process library (LWP) provides a mechanism to support multiple threads of control that share a single address space. Under SunOS, the address space is derived from a single forked (``heavyweight'') process. Each thread has its own stack segment (specified when the thread is created) so that it can access local variables and make procedure calls independently of other threads. The collection of threads sharing an address space is called a pod. Under SunOS, threads share all of the resources of the heavyweight process that contains the pod, including descriptors and signal handlers.
The LWP provides a means for creating and destroying threads, message exchange between threads, manipulating condition variables and monitors, handling synchronous exceptions, mapping asynchronous events into messages, mapping synchronous events into exceptions, arranging for special per-thread context, multiplexing the clock for timeouts, and scheduling threads both preemptively and non-preemptively.
The LWP system exists as a library of routines (/usr/lib/liblwp.a) linked in (-llwp) with a client program which should #include the file <lwp/lwp.h>. main is transparently converted into a lightweight process as soon as it attempts to use any LWP primitives.
When an object created by a LWP primitive is destroyed, every attempt is made to clean up after it. For example, if a thread dies, all threads blocked on sends to or receives from that thread are unblocked, and all monitor locks held by the dead thread are released.
Because there is no kernel support for threads at present, system calls effectively block the entire pod. By linking in the non-blocking I/O library (-lnbio) ahead of the LWP library, you can alleviate this problem for those system calls that can issue a signal when a system call would be profitable to try. This library (which redefines some system calls) uses asynchronous I/O and events (for example, SIGCHLD and SIGIO) to make blocking less painful. The system calls remapped by the nbio library are: open.2v socket.2 pipe.2v close.2v read.2v write.2v send.2 recv.2 accept.2 connect.2 select (2) and wait.2v
LWP primitives return non-negative integers on success. On errors, they return -1. See lwp_perror.3l for details on error handling.
Lightweight Processes in the [a manual with the abbreviation SSO]
lwp_self(tid) lwp_getstate(tid, statvec) lwp_setregs(tid, machstate) lwp_getregs(tid, machstate) lwp_ping(tid) lwp_create(tid, pc, prio, flags, stack, nargs, arg1, ..., argn) lwp_destroy(tid) lwp_enumerate(vec, maxsize) pod_setexit(status) pod_getexit() pod_exit(status) SAMETHREAD(t1, t2)
pod_setmaxpri(maxprio) pod_getmaxpri() pod_getmaxsize() lwp_resched(prio) lwp_setpri(tid, prio) lwp_sleep(timeout) lwp_suspend(tid) lwp_resume(tid) lwp_yield(tid) lwp_join(tid)
lwp_geterr() lwp_perror(s) lwp_errstr()
msg_send(tid, argbuf, argsize, resbuf, ressize) msg_recv(tid, argbuf, argsize, resbuf, ressize, timeout) MSG_RECVALL(tid, argbuf, argsize, resbuf, ressize, timeout) msg_reply(tid) msg_enumsend(vec, maxsize) msg_enumrecv(vec, maxsize)
agt_create(agt, event, memory) agt_enumerate(vec, maxsize) agt_trap(event)
mon_create(mid) mon_destroy(mid) mon_enter(mid) mon_exit(mid) mon_enumerate(vec, maxsize) mon_waiters (mid, owner, vec, maxsize) mon_cond_enter(mid) mon_break(mid) MONITOR(mid) SAMEMON(m1, m2)
cv_create(cv, mid) cv_destroy(cv) cv_wait(cv) cv_notify(cv) cv_send(cv, tid) cv_broadcast(cv) cv_enumerate(vec, maxsize) cv_waiters(cv, vec, maxsize) SAMECV(c1, c2)
exc_handle(pattern, func, arg) exc_unhandle() (*exc_bound(pattern, arg))() exc_notify(pattern) exc_raise(pattern) exc_on_exit(func, arg) exc_uniqpatt()
lwp_ctxinit(tid, cookie) lwp_ctxremove(tid, cookie) lwp_ctxset(save, restore, ctxsize, optimise) lwp_ctxmemget(mem, tid, ctx) lwp_ctxmemset(mem, tid, ctx) lwp_fpset(tid) lwp_libcset(tid)
CHECK(location, result) lwp_setstkcache(minsize, numstks) lwp_newstk() lwp_datastk(data, size, addr) lwp_stkcswset(tid, limit) lwp_checkstkset(tid, limit) STKTOP(s)
There is no language support available from C.
There is no kernel support yet. Thus system calls in different threads cannot execute in parallel.
Killing a process that uses the non-blocking I/O library may leave
objects (such as its standard input) in a non-blocking state.
This could cause confusion to the shell.
Name Appears on Page Description agt_create agt_create(3L) map LWP events into messages agt_enumerate agt_create(3L) map LWP events into messages agt_trap agt_create(3L) map LWP events into messages CHECK lwp_newstk(3L) LWP stack management cv_broadcast cv_create(3L) manage LWP condition variables cv_create cv_create(3L) manage LWP condition variables cv_destroy cv_create(3L) manage LWP condition variables cv_enumerate cv_create(3L) manage LWP condition variables cv_notify cv_create(3L) manage LWP condition variables cv_send cv_create(3L) manage LWP condition variables cv_wait cv_create(3L) manage LWP condition variables cv_waiters cv_create(3L) manage LWP condition variables exc_bound exc_handle(3L) LWP exception handling exc_handle exc_handle(3L) LWP exception handling exc_notify exc_handle(3L) LWP exception handling exc_on_exit exc_handle(3L) LWP exception handling exc_raise exc_handle(3L) LWP exception handling exc_unhandle exc_handle(3L) LWP exception handling exc_uniqpatt exc_handle(3L) LWP exception handling lwp_checkstkset lwp_newstk(3L) LWP stack management lwp_create lwp_create(3L) LWP thread creation and destruction primitives lwp_ctxinit lwp_ctxinit(3L) special LWP context operations lwp_ctxmemget lwp_ctxinit(3L) special LWP context operations lwp_ctxmemset lwp_ctxinit(3L) special LWP context operations lwp_ctxremove lwp_ctxinit(3L) special LWP context operations lwp_ctxset lwp_ctxinit(3L) special LWP context operations lwp_datastk lwp_newstk(3L) LWP stack management lwp_destroy lwp_create(3L) LWP thread creation and destruction primitives lwp_enumerate lwp_status(3L) LWP status information lwp_errstr lwp_perror(3L) LWP error handling lwp_fpset lwp_ctxinit(3L) special LWP context operations lwp_geterr lwp_perror(3L) LWP error handling lwp_getregs lwp_status(3L) LWP status information lwp_getstate lwp_status(3L) LWP status information lwp_join lwp_yield(3L) control LWP scheduling lwp_libcset lwp_ctxinit(3L) special LWP context operations lwp_newstk lwp_newstk(3L) LWP stack management lwp_perror lwp_perror(3L) LWP error handling lwp_ping lwp_status(3L) LWP status information lwp_resched lwp_yield(3L) control LWP scheduling lwp_resume lwp_yield(3L) control LWP scheduling lwp_self lwp_status(3L) LWP status information lwp_setpri lwp_yield(3L) control LWP scheduling lwp_setregs lwp_status(3L) LWP status information lwp_setstkcache lwp_newstk(3L) LWP stack management lwp_sleep lwp_yield(3L) control LWP scheduling lwp_stkcswset lwp_newstk(3L) LWP stack management lwp_suspend lwp_yield(3L) control LWP scheduling lwp_yield lwp_yield(3L) control LWP scheduling MINSTACKSZ lwp_newstk(3L) LWP stack management mon_break mon_create(3L) LWP routines to manage critical sections mon_cond_enter mon_create(3L) LWP routines to manage critical sections mon_create mon_create(3L) LWP routines to manage critical sections mon_destroy mon_create(3L) LWP routines to manage critical sections mon_enter mon_create(3L) LWP routines to manage critical sections mon_enumerate mon_create(3L) LWP routines to manage critical sections mon_exit mon_create(3L) LWP routines to manage critical sections mon_waiters mon_create(3L) LWP routines to manage critical sections MONITOR mon_create(3L) LWP routines to manage critical sections msg_enumrecv msg_send(3L) LWP send and receive messages msg_enumsend msg_send(3L) LWP send and receive messages msg_recv msg_send(3L) LWP send and receive messages MSG_RECVALL msg_send(3L) LWP send and receive messages msg_reply msg_send(3L) LWP send and receive messages msg_send msg_send(3L) LWP send and receive messages pod_exit lwp_create(3L) LWP thread creation and destruction primitives pod_getexit lwp_create(3L) LWP thread creation and destruction primitives pod_getmaxpri pod_getmaxpri(3L) control LWP scheduling priority pod_getmaxsize pod_getmaxpri(3L) control LWP scheduling priority pod_setexit lwp_create(3L) LWP thread creation and destruction primitives pod_setmaxpri pod_getmaxpri(3L) control LWP scheduling priority
SAMECV cv_create(3L) manage LWP condition variables SAMEMON mon_create(3L) LWP routines to manage critical sections SAMETHREAD lwp_create(3L) LWP thread creation and destruction primitives STKTOP lwp_newstk(3L) LWP stack management
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Created by unroff & hp-tools. © somebody (See intro for details). All Rights Reserved. Last modified 11/5/97