Standards, Environments, and Macros threads(5)
NAME
threads, pthreads - POSIX pthreads and Solaris threads con-
cepts
SYNOPSIS
POSIX
cc -mt [ flag... ] file... [ -lrt library... ]
#include
Solaris
cc -mt [ flag... ] file... [ library... ]
#include
#include
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 coun-
terparts 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 func-
tions 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.
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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 avail-
able either in POSIX pthreads or Solaris threads, a hyphen
(-) appears in the column.
Functions Related to Creation
POSIX Solaris
pthreadcreate() thrcreate()
pthreadattrinit() -
pthreadattrsetdetachstate() -
pthreadattrgetdetachstate() -
pthreadattrsetinheritsched() -
pthreadattrgetinheritsched() -
pthreadattrsetschedparam() -
pthreadattrgetschedparam() -
pthreadattrsetschedpolicy() -
pthreadattrgetschedpolicy() -
pthreadattrsetscope() -
pthreadattrgetscope() -
pthreadattrsetstackaddr() -
pthreadattrgetstackaddr() -
pthreadattrsetstacksize() -
pthreadattrgetstacksize() -
pthreadattrgetguardsize() -
pthreadattrsetguardsize() -
pthreadattrdestroy() -
- thrminstack()
Functions Related to Exit
POSIX Solaris
pthreadexit() threxit()
pthreadjoin() thrjoin()
pthreaddetach() -
Functions Related to Thread Specific Data
POSIX Solaris
pthreadkeycreate() thrkeycreate()
pthreadsetspecific() thrsetspecific()
pthreadgetspecific() thrgetspecific()
pthreadkeydelete() -
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Functions Related to Signals
POSIX Solaris
pthreadsigmask() thrsigsetmask()
pthreadkill() thrkill()
Functions Related to IDs
POSIX Solaris
pthreadself() thrself()
pthreadequal() -
- thrmain()
Functions Related to Scheduling
POSIX Solaris
- thryield()
- thrsuspend()
- thrcontinue()
pthreadsetconcurrency() thrsetconcurrency()
pthreadgetconcurrency() thrgetconcurrency()
pthreadsetschedparam() thrsetprio()
pthreadsetschedprio() thrsetprio()
pthreadgetschedparam() thrgetprio()
Functions Related to Cancellation
POSIX Solaris
pthreadcancel() -
pthreadsetcancelstate() -
pthreadsetcanceltype() -
pthreadtestcancel() -
pthreadcleanuppop() -
pthreadcleanuppush() -
Functions Related to Mutexes
POSIX Solaris
pthreadmutexinit() mutexinit()
pthreadmutexattrinit() -
pthreadmutexattrsetpshared() -
pthreadmutexattrgetpshared() -
pthreadmutexattrsetprotocol() -
pthreadmutexattrgetprotocol() -
pthreadmutexattrsetprioceiling() -
pthreadmutexattrgetprioceiling() -
pthreadmutexattrsettype() -
pthreadmutexattrgettype() -
pthreadmutexattrsetrobust() -
pthreadmutexattrgetrobust() -
pthreadmutexattrdestroy() -
pthreadmutexsetprioceiling() -
pthreadmutexgetprioceiling() -
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pthreadmutexlock() mutexlock()
pthreadmutextrylock() mutextrylock()
pthreadmutexunlock() mutexunlock()
pthreadmutexdestroy() mutexdestroy()
Functions Related to Condition Variables
POSIX Solaris
pthreadcondinit() condinit()
pthreadcondattrinit() -
pthreadcondattrsetpshared() -
pthreadcondattrgetpshared() -
pthreadcondattrdestroy() -
pthreadcondwait() condwait()
pthreadcondtimedwait() condtimedwait()
pthreadcondsignal() condsignal()
pthreadcondbroadcast() condbroadcast()
pthreadconddestroy() conddestroy()
Functions Related to Reader/Writer Locking
POSIX Solaris
pthreadrwlockinit() rwlockinit()
pthreadrwlockrdlock() rwrdlock()
pthreadrwlocktryrdlock() rwtryrdlock()
pthreadrwlockwrlock() rwwrlock()
pthreadrwlocktrywrlock() rwtrywrlock()
pthreadrwlockunlock() rwunlock()
pthreadrwlockdestroy() rwlockdestroy()
pthreadrwlockattrinit() -
pthreadrwlockattrdestroy() -
pthreadrwlockattrgetpshared() -
pthreadrwlockattrsetpshared() -
Functions Related to Semaphores
POSIX Solaris
seminit() semainit()
semopen() -
semclose() -
semwait() semawait()
semtrywait() sematrywait()
sempost() semapost()
semgetvalue() -
semunlink() -
semdestroy() semadestroy()
Functions Related to fork() Clean Up
POSIX Solaris
pthreadatfork() -
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Functions Related to Limits
POSIX Solaris
pthreadonce() -
Functions Related to Debugging
POSIX Solaris
- thrstksegment()
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 con-
currency.
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 pthreadatfork(3C) to wait for and
acquire those mutexes prior to calling fork().
SCHEDULING
POSIX Threads
Solaris supports the following three POSIX scheduling poli-
cies:
SCHEDOTHER Traditional Timesharing scheduling policy. It
is based on the timesharing (TS) scheduling
class.
SCHEDFIFO First-In-First-Out scheduling policy. Threads
scheduled to this policy, if not preempted by
a higher priority, will proceed until comple-
tion. Such threads are in real-time (RT)
scheduling class. The calling process must
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have a effective user ID of 0.
SCHEDR 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:
SCHEDIA Threads are scheduled according to the Inter-
Active Class (IA) policy as described in
priocntl(2).
SCHEDFS Threads are scheduled according to the Fair-
Share Class (FS) policy as described in
priocntl(2).
SCHEDFX Threads are scheduled according to the Fixed-
Priority Class (FX) policy as described in
priocntl(2).
Solaris Threads
Only scheduling policy supported is SCHEDOTHER, which is
timesharing, based on the TS scheduling class.
ERORS
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 -DRENTRANT and aug-
ments the set of support libraries properly.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
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ATRIBUTE TYPE ATRIBUTE VALUE
MT-Level MT-Safe, Fork 1-Safe
SEE ALSO
crle(1), fork(2), priocntl(2), libpthread(3LIB),
librt(3LIB), libthread(3LIB), pthreadatfork(3C),
pthreadcreate(3C), attributes(5), standards(5)
Linker and Libraries Guide
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