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2359035ac5
With current kernel versions, the check does not reliably detect that
unavailable CPUs are requested, for these reasons:
(1) The kernel will silently ignore non-allowed CPUs, that is, CPUs
which are physically present but disallowed for the thread
based on system configuration.
(2) Similarly, CPU bits which lack an online CPU (possible CPUs)
are ignored.
(3) The existing probing code assumes that the CPU mask size is a
power of two and at least 1024. Neither has it to be a power
of two, nor is the minimum possible value 1024, so the value
determined is often too large. This means that the CPU set
size check in glibc accepts CPU bits beyond the actual hard
system limit.
(4) Future kernel versions may not even have a fixed CPU set size.
After the removal of the probing code, the kernel still returns
EINVAL if no CPU in the requested set remains which can run the
thread after the affinity change.
Applications which care about the exact affinity mask will have
to query it using sched_getaffinity after setting it. Due to the
effects described above, this commit does not change this.
The new tests supersede tst-getcpu, which is removed. This
addresses bug 19164 because the new tests allocate CPU sets
dynamically.
* nptl/check-cpuset.h: Remove.
* nptl/pthread_attr_setaffinity.c (__pthread_attr_setaffinity_new):
Remove CPU set size check.
* nptl/pthread_setattr_default_np.c (pthread_setattr_default_np):
Likewise.
* sysdeps/unix/sysv/linux/check-cpuset.h: Remove.
* sysdeps/unix/sysv/linux/pthread_setaffinity.c
(__kernel_cpumask_size, __determine_cpumask_size): Remove.
(__pthread_setaffinity_new): Remove CPU set size check.
* sysdeps/unix/sysv/linux/sched_setaffinity.c
(__kernel_cpumask_size): Remove.
(__sched_setaffinity_new): Remove CPU set size check.
* manual/threads.texi (Default Thread Attributes): Remove stale
reference to check_cpuset_attr, determine_cpumask_size in comment.
* sysdeps/unix/sysv/linux/Makefile [$(subdir) == posix] (tests):
Remove tst-getcpu. Add tst-affinity, tst-affinity-pid.
[$(subdir) == nptl] (tests): Add tst-thread-affinity-pthread,
tst-thread-affinity-pthread2, tst-thread-affinity-sched.
* sysdeps/unix/sysv/linux/tst-affinity.c: New file.
* sysdeps/unix/sysv/linux/tst-affinity-pid.c: New file.
* sysdeps/unix/sysv/linux/tst-skeleton-affinity.c: New skeleton test file.
* sysdeps/unix/sysv/linux/tst-thread-affinity-sched.c: New file.
* sysdeps/unix/sysv/linux/tst-thread-affinity-pthread.c: New file.
* sysdeps/unix/sysv/linux/tst-thread-affinity-pthread2.c: New file.
* sysdeps/unix/sysv/linux/tst-thread-skeleton-affinity.c: New
skeleton test file.
* sysdeps/unix/sysv/linux/tst-getcpu.c: Remove. Superseded by
tst-affinity-pid.
253 lines
7.9 KiB
Plaintext
253 lines
7.9 KiB
Plaintext
@node POSIX Threads
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@c @node POSIX Threads, Internal Probes, Cryptographic Functions, Top
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@chapter POSIX Threads
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@c %MENU% POSIX Threads
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@cindex pthreads
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This chapter describes the @glibcadj{} POSIX Thread implementation.
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@menu
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* Thread-specific Data:: Support for creating and
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managing thread-specific data
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* Non-POSIX Extensions:: Additional functions to extend
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POSIX Thread functionality
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@end menu
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@node Thread-specific Data
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@section Thread-specific Data
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The @glibcadj{} implements functions to allow users to create and manage
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data specific to a thread. Such data may be destroyed at thread exit,
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if a destructor is provided. The following functions are defined:
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@comment pthread.h
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@comment POSIX
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@deftypefun int pthread_key_create (pthread_key_t *@var{key}, void (*@var{destructor})(void*))
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c pthread_key_create ok
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@c KEY_UNUSED ok
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@c KEY_USABLE ok
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Create a thread-specific data key for the calling thread, referenced by
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@var{key}.
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Objects declared with the C++11 @code{thread_local} keyword are destroyed
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before thread-specific data, so they should not be used in thread-specific
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data destructors or even as members of the thread-specific data, since the
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latter is passed as an argument to the destructor function.
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@end deftypefun
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@comment pthread.h
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@comment POSIX
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@deftypefun int pthread_key_delete (pthread_key_t @var{key})
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c pthread_key_delete ok
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@c This uses atomic compare and exchange to increment the seq number
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@c after testing it's not a KEY_UNUSED seq number.
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@c KEY_UNUSED dup ok
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Destroy the thread-specific data @var{key} in the calling thread. The
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destructor for the thread-specific data is not called during destruction, nor
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is it called during thread exit.
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@end deftypefun
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@comment pthread.h
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@comment POSIX
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@deftypefun void *pthread_getspecific (pthread_key_t @var{key})
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c pthread_getspecific ok
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Return the thread-specific data associated with @var{key} in the calling
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thread.
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@end deftypefun
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@comment pthread.h
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@comment POSIX
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@deftypefun int pthread_setspecific (pthread_key_t @var{key}, const void *@var{value})
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@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{} @ascuheap{}}@acunsafe{@acucorrupt{} @acsmem{}}}
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@c pthread_setspecific @asucorrupt @ascuheap @acucorrupt @acsmem
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@c a level2 block may be allocated by a signal handler after
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@c another call already made a decision to allocate it, thus losing
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@c the allocated value. the seq number is updated before the
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@c value, which might cause an earlier-generation value to seem
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@c current if setspecific is cancelled or interrupted by a signal
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@c KEY_UNUSED ok
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@c calloc dup @ascuheap @acsmem
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Associate the thread-specific @var{value} with @var{key} in the calling thread.
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@end deftypefun
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@node Non-POSIX Extensions
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@section Non-POSIX Extensions
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In addition to implementing the POSIX API for threads, @theglibc{} provides
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additional functions and interfaces to provide functionality not specified in
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the standard.
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@menu
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* Default Thread Attributes:: Setting default attributes for
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threads in a process.
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@end menu
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@node Default Thread Attributes
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@subsection Setting Process-wide defaults for thread attributes
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@Theglibc{} provides non-standard API functions to set and get the default
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attributes used in the creation of threads in a process.
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@comment pthread.h
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@comment GNU
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@deftypefun int pthread_getattr_default_np (pthread_attr_t *@var{attr})
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@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{}}}
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@c Takes lock around read from default_pthread_attr.
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Get the default attribute values and set @var{attr} to match. This
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function returns @math{0} on success and a non-zero error code on
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failure.
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@end deftypefun
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@comment pthread.h
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@comment GNU
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@deftypefun int pthread_setattr_default_np (pthread_attr_t *@var{attr})
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@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@aculock{} @acsmem{}}}
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@c pthread_setattr_default_np @ascuheap @asulock @aculock @acsmem
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@c check_sched_policy_attr ok
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@c check_sched_priority_attr ok
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@c sched_get_priority_min dup ok
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@c sched_get_priority_max dup ok
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@c check_stacksize_attr ok
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@c lll_lock @asulock @aculock
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@c free dup @ascuheap @acsmem
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@c realloc dup @ascuheap @acsmem
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@c memcpy dup ok
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@c lll_unlock @asulock @aculock
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Set the default attribute values to match the values in @var{attr}. The
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function returns @math{0} on success and a non-zero error code on failure.
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The following error codes are defined for this function:
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@table @code
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@item EINVAL
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At least one of the values in @var{attr} does not qualify as valid for the
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attributes or the stack address is set in the attribute.
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@item ENOMEM
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The system does not have sufficient memory.
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@end table
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@end deftypefun
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@c FIXME these are undocumented:
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@c pthread_atfork
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@c pthread_attr_destroy
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@c pthread_attr_getaffinity_np
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@c pthread_attr_getdetachstate
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@c pthread_attr_getguardsize
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@c pthread_attr_getinheritsched
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@c pthread_attr_getschedparam
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@c pthread_attr_getschedpolicy
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@c pthread_attr_getscope
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@c pthread_attr_getstack
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@c pthread_attr_getstackaddr
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@c pthread_attr_getstacksize
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@c pthread_attr_init
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@c pthread_attr_setaffinity_np
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@c pthread_attr_setdetachstate
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@c pthread_attr_setguardsize
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@c pthread_attr_setinheritsched
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@c pthread_attr_setschedparam
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@c pthread_attr_setschedpolicy
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@c pthread_attr_setscope
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@c pthread_attr_setstack
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@c pthread_attr_setstackaddr
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@c pthread_attr_setstacksize
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@c pthread_barrierattr_destroy
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@c pthread_barrierattr_getpshared
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@c pthread_barrierattr_init
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@c pthread_barrierattr_setpshared
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@c pthread_barrier_destroy
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@c pthread_barrier_init
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@c pthread_barrier_wait
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@c pthread_cancel
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@c pthread_cleanup_push
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@c pthread_cleanup_pop
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@c pthread_condattr_destroy
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@c pthread_condattr_getclock
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@c pthread_condattr_getpshared
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@c pthread_condattr_init
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@c pthread_condattr_setclock
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@c pthread_condattr_setpshared
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@c pthread_cond_broadcast
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@c pthread_cond_destroy
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@c pthread_cond_init
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@c pthread_cond_signal
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@c pthread_cond_timedwait
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@c pthread_cond_wait
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@c pthread_create
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@c pthread_detach
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@c pthread_equal
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@c pthread_exit
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@c pthread_getaffinity_np
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@c pthread_getattr_np
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@c pthread_getconcurrency
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@c pthread_getcpuclockid
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@c pthread_getname_np
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@c pthread_getschedparam
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@c pthread_join
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@c pthread_kill
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@c pthread_kill_other_threads_np
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@c pthread_mutexattr_destroy
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@c pthread_mutexattr_getkind_np
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@c pthread_mutexattr_getprioceiling
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@c pthread_mutexattr_getprotocol
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@c pthread_mutexattr_getpshared
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@c pthread_mutexattr_getrobust
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@c pthread_mutexattr_getrobust_np
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@c pthread_mutexattr_gettype
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@c pthread_mutexattr_init
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@c pthread_mutexattr_setkind_np
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@c pthread_mutexattr_setprioceiling
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@c pthread_mutexattr_setprotocol
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@c pthread_mutexattr_setpshared
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@c pthread_mutexattr_setrobust
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@c pthread_mutexattr_setrobust_np
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@c pthread_mutexattr_settype
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@c pthread_mutex_consistent
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@c pthread_mutex_consistent_np
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@c pthread_mutex_destroy
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@c pthread_mutex_getprioceiling
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@c pthread_mutex_init
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@c pthread_mutex_lock
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@c pthread_mutex_setprioceiling
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@c pthread_mutex_timedlock
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@c pthread_mutex_trylock
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@c pthread_mutex_unlock
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@c pthread_once
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@c pthread_rwlockattr_destroy
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@c pthread_rwlockattr_getkind_np
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@c pthread_rwlockattr_getpshared
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@c pthread_rwlockattr_init
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@c pthread_rwlockattr_setkind_np
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@c pthread_rwlockattr_setpshared
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@c pthread_rwlock_destroy
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@c pthread_rwlock_init
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@c pthread_rwlock_rdlock
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@c pthread_rwlock_timedrdlock
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@c pthread_rwlock_timedwrlock
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@c pthread_rwlock_tryrdlock
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@c pthread_rwlock_trywrlock
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@c pthread_rwlock_unlock
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@c pthread_rwlock_wrlock
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@c pthread_self
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@c pthread_setaffinity_np
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@c pthread_setcancelstate
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@c pthread_setcanceltype
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@c pthread_setconcurrency
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@c pthread_setname_np
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@c pthread_setschedparam
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@c pthread_setschedprio
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@c pthread_sigmask
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@c pthread_sigqueue
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@c pthread_spin_destroy
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@c pthread_spin_init
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@c pthread_spin_lock
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@c pthread_spin_trylock
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@c pthread_spin_unlock
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@c pthread_testcancel
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@c pthread_timedjoin_np
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@c pthread_tryjoin_np
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@c pthread_yield
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