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man pages section 7: Standards, Environments, Macros, Character Sets, and Miscellany

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Updated: Wednesday, August 8, 2018
 
 

threads(7)

Name

threads, pthreads - POSIX pthreads and Solaris threads concepts

Synopsis

POSIX

#include <pthread.h> 

Solaris

#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 environments. POSIX and Solaris threads require different source code and include files. See SYNOPSIS.

Similarities

Most of the POSIX and Solaris threading functions have counterparts with each other. POSIX function names, with the exception of the semaphore 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:

  • POSIX threads are more portable.

  • POSIX threads establish characteristics for each thread according to configurable attribute objects.

  • POSIX pthreads implement thread cancellation.

  • POSIX pthreads enforce scheduling algorithms.

  • POSIX pthreads allow for clean-up handlers for fork(2) calls.

  • Solaris threads can be suspended and continued.

  • 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()
pthread_getattr_np()
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_gettype_np()
pthread_rwlockattr_setpshared()
pthread_rwlockattr_settype_np()

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 occasional-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 the {PRIV_PROC_PRIOCNTL} privilege asserted in its effective set.

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 the {PRIV_PROC_PRIOCNTL} privilege asserted in its effective set.

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).

Attributes

See attributes(7) 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), pthread_atfork(3C), pthread_create(3C), libpthread(3LIB), librt(3LIB), libthread(3LIB), attributes(7), privileges(7), standards(7)

Oracle Solaris 11.4 Linkers and Libraries Guide