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threads(5) [opensolaris man page]

threads(5)						Standards, Environments, and Macros						threads(5)

threads, pthreads - POSIX pthreads and Solaris threads concepts SYNOPSIS
POSIX cc -mt [ flag... ] file... [ -lrt library... ] #include <pthread.h> Solaris cc -mt [ flag... ] file... [ library... ] #include <sched.h> #include <thread.h> DESCRIPTION
POSIX and Solaris threads each have their own implementation within libc(3LIB). Both implementations are interoperable, their functionality similar, and can be used within the same application. Only POSIX threads are guaranteed to be fully portable to other POSIX-compliant envi- ronments. POSIX and Solaris threads require different source, include files and linking libraries. See SYNOPSIS. Similarities Most of the POSIX and Solaris threading functions have counterparts with each other. POSIX function names, with the exception of the sema- phore names, have a "pthread" prefix. Function names for similar POSIX and Solaris functions have similar endings. Typically, similar POSIX and Solaris functions have the same number and use of arguments. Differences POSIX pthreads and Solaris threads differ in the following ways: o POSIX threads are more portable. o POSIX threads establish characteristics for each thread according to configurable attribute objects. o POSIX pthreads implement thread cancellation. o POSIX pthreads enforce scheduling algorithms. o POSIX pthreads allow for clean-up handlers for fork(2) calls. o Solaris threads can be suspended and continued. o Solaris threads implement daemon threads, for whose demise the process does not wait. FUNCTION COMPARISON
The following table compares the POSIX pthreads and Solaris threads functions. When a comparable interface is not available either in POSIX pthreads or Solaris threads, a hyphen (-) appears in the column. Functions Related to Creation POSIX Solaris pthread_create() thr_create() pthread_attr_init() - pthread_attr_setdetachstate() - pthread_attr_getdetachstate() - pthread_attr_setinheritsched() - pthread_attr_getinheritsched() - pthread_attr_setschedparam() - pthread_attr_getschedparam() - pthread_attr_setschedpolicy() - pthread_attr_getschedpolicy() - pthread_attr_setscope() - pthread_attr_getscope() - pthread_attr_setstackaddr() - pthread_attr_getstackaddr() - pthread_attr_setstacksize() - pthread_attr_getstacksize() - pthread_attr_getguardsize() - pthread_attr_setguardsize() - pthread_attr_destroy() - - thr_min_stack() Functions Related to Exit POSIX Solaris pthread_exit() thr_exit() pthread_join() thr_join() pthread_detach() - Functions Related to Thread Specific Data POSIX Solaris pthread_key_create() thr_keycreate() pthread_setspecific() thr_setspecific() pthread_getspecific() thr_getspecific() pthread_key_delete() - Functions Related to Signals POSIX Solaris pthread_sigmask() thr_sigsetmask() pthread_kill() thr_kill() Functions Related to IDs POSIX Solaris pthread_self() thr_self() pthread_equal() - - thr_main() Functions Related to Scheduling POSIX Solaris - thr_yield() - thr_suspend() - thr_continue() pthread_setconcurrency() thr_setconcurrency() pthread_getconcurrency() thr_getconcurrency() pthread_setschedparam() thr_setprio() pthread_setschedprio() thr_setprio() pthread_getschedparam() thr_getprio() Functions Related to Cancellation POSIX Solaris pthread_cancel() - pthread_setcancelstate() - pthread_setcanceltype() - pthread_testcancel() - pthread_cleanup_pop() - pthread_cleanup_push() - Functions Related to Mutexes POSIX Solaris pthread_mutex_init() mutex_init() pthread_mutexattr_init() - pthread_mutexattr_setpshared() - pthread_mutexattr_getpshared() - pthread_mutexattr_setprotocol() - pthread_mutexattr_getprotocol() - pthread_mutexattr_setprioceiling() - pthread_mutexattr_getprioceiling() - pthread_mutexattr_settype() - pthread_mutexattr_gettype() - pthread_mutexattr_setrobust() - pthread_mutexattr_getrobust() - pthread_mutexattr_destroy() - pthread_mutex_setprioceiling() - pthread_mutex_getprioceiling() - pthread_mutex_lock() mutex_lock() pthread_mutex_trylock() mutex_trylock() pthread_mutex_unlock() mutex_unlock() pthread_mutex_destroy() mutex_destroy() Functions Related to Condition Variables POSIX Solaris pthread_cond_init() cond_init() pthread_condattr_init() - pthread_condattr_setpshared() - pthread_condattr_getpshared() - pthread_condattr_destroy() - pthread_cond_wait() cond_wait() pthread_cond_timedwait() cond_timedwait() pthread_cond_signal() cond_signal() pthread_cond_broadcast() cond_broadcast() pthread_cond_destroy() cond_destroy() Functions Related to Reader/Writer Locking POSIX Solaris pthread_rwlock_init() rwlock_init() pthread_rwlock_rdlock() rw_rdlock() pthread_rwlock_tryrdlock() rw_tryrdlock() pthread_rwlock_wrlock() rw_wrlock() pthread_rwlock_trywrlock() rw_trywrlock() pthread_rwlock_unlock() rw_unlock() pthread_rwlock_destroy() rwlock_destroy() pthread_rwlockattr_init() - pthread_rwlockattr_destroy() - pthread_rwlockattr_getpshared() - pthread_rwlockattr_setpshared() - Functions Related to Semaphores POSIX Solaris sem_init() sema_init() sem_open() - sem_close() - sem_wait() sema_wait() sem_trywait() sema_trywait() sem_post() sema_post() sem_getvalue() - sem_unlink() - sem_destroy() sema_destroy() Functions Related to fork() Clean Up POSIX Solaris pthread_atfork() - Functions Related to Limits POSIX Solaris pthread_once() - Functions Related to Debugging POSIX Solaris - thr_stksegment() LOCKING
Synchronization Multithreaded behavior is asynchronous, and therefore, optimized for concurrent and parallel processing. As threads, always from within the same process and sometimes from multiple processes, share global data with each other, they are not guaranteed exclusive access to the shared data at any point in time. Securing mutually exclusive access to shared data requires synchronization among the threads. Both POSIX and Solaris implement four synchronization mechanisms: mutexes, condition variables, reader/writer locking (optimized frequent-read occa- sional-write mutex), and semaphores. Synchronizing multiple threads diminishes their concurrency. The coarser the grain of synchronization, that is, the larger the block of code that is locked, the lesser the concurrency. MT fork() If a threads program calls fork(2), it implicitly calls fork1(2), which replicates only the calling thread. Should there be any outstanding mutexes throughout the process, the application should call pthread_atfork(3C) to wait for and acquire those mutexes prior to calling fork(). SCHEDULING
POSIX Threads Solaris supports the following three POSIX scheduling policies: SCHED_OTHER Traditional Timesharing scheduling policy. It is based on the timesharing (TS) scheduling class. SCHED_FIFO First-In-First-Out scheduling policy. Threads scheduled to this policy, if not preempted by a higher priority, will proceed until completion. Such threads are in real-time (RT) scheduling class. The calling process must have a effective user ID of 0. SCHED_RR Round-Robin scheduling policy. Threads scheduled to this policy, if not preempted by a higher priority, will execute for a time period determined by the system. Such threads are in real-time (RT) scheduling class and the calling process must have a effective user ID of 0. In addition to the POSIX-specified scheduling policies above, Solaris also supports these scheduling policies: SCHED_IA Threads are scheduled according to the Inter-Active Class (IA) policy as described in priocntl(2). SCHED_FSS Threads are scheduled according to the Fair-Share Class (FSS) policy as described in priocntl(2). SCHED_FX Threads are scheduled according to the Fixed-Priority Class (FX) policy as described in priocntl(2). Solaris Threads Only scheduling policy supported is SCHED_OTHER, which is timesharing, based on the TS scheduling class. ERRORS
In a multithreaded application, EINTR can be returned from blocking system calls when another thread calls forkall(2). USAGE
-mt compiler option The -mt compiler option compiles and links for multithreaded code. It compiles source files with -D_REENTRANT and augments the set of sup- port libraries properly. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe, Fork 1-Safe | +-----------------------------+-----------------------------+ SEE ALSO
crle(1), fork(2), priocntl(2), libpthread(3LIB), librt(3LIB), libthread(3LIB), pthread_atfork(3C), pthread_create(3C), attributes(5), stan- dards(5) Linker and Libraries Guide SunOS 5.11 11 Nov 2008 threads(5)

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