threads(5)
Name
threads, pthreads - POSIX pthreads and Solaris threads
concepts
Synopsis
POSIX
cc –mt [ flag... ] file... [ 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 environments. 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 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
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
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
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).
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 support libraries properly.
Attributes
See attributes(5) for
descriptions of the following attributes:
|
|
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), privileges(5), standards(5)
Oracle Solaris 11.2 Linkers and Libraries Guide