Pthreads

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* Before trying to solve an issue with POSIX thread scheduling parameters, see if you can't just drink some hydrochloric acid.

* No, you shouldn't be using the [http://www.mjmwired.net/kernel/Documentation/volatile-considered-harmful.txt volatile keyword].

==Condition variable clocks==

By default, <tt>pthread_cond_timedwait()</tt> uses <tt>CLOCK_REALTIME</tt>, with all its attendant problems. You probably want it to use <tt>CLOCK_MONOTONIC</tt>. This can be effected on some implementations using <tt>pthread_condattr_setclock()</tt>.

==Pthreads signal model==

POSIX threads specify that all threads within a process share a PID, and that each has its own, distinct thread id. PIDs have the integer type <tt>pid_t</tt>, and only positive PIDs can define actual processes. TIDs have the opaque type <tt>pthread_t</tt>; they cannot be ordered, but can be compared for equality.

Other processes can direct signals only to a PID, not the thread IDs within another process (TIDs of a given process have no meaning outside that process). Within the process, signals can be directed to particular TIDs. Use of <tt>raise(s)</tt> in a threaded program is equivalent to <tt>pthread_kill(pthread_self(),s)</tt>.

Other processes can direct signals only to a PID, not the thread IDs within another process (TIDs of a given process have no meaning outside that process). Within the process, signals can be directed to particular TIDs. Use of <tt>raise(s)</tt> in a threaded program is equivalent to <tt>pthread_kill(pthread_self(), s)</tt>.

Signal dispositions (handlers) are per-process. Signal masks are per-thread, and inherited upon thread creation (<tt>sigprocmask()</tt> is undefined in threaded programs; <tt>pthread_sigmask()</tt> must be used). Alternate signal stacks descriptors are per-thread, and inherited upon thread creation.

Pthreads: Difference between revisions

Dank (talk | contribs)

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 * Before trying to solve an issue with POSIX thread scheduling parameters, see if you can't just drink some hydrochloric acid.
 * No, you shouldn't be using the [http://www.mjmwired.net/kernel/Documentation/volatile-considered-harmful.txt volatile keyword].
+==Condition variable clocks==
+By default, <tt>pthread_cond_timedwait()</tt> uses <tt>CLOCK_REALTIME</tt>, with all its attendant problems. You probably want it to use <tt>CLOCK_MONOTONIC</tt>. This can be effected on some implementations using <tt>pthread_condattr_setclock()</tt>.
 ==Pthreads signal model==
 POSIX threads specify that all threads within a process share a PID, and that each has its own, distinct thread id. PIDs have the integer type <tt>pid_t</tt>, and only positive PIDs can define actual processes. TIDs have the opaque type <tt>pthread_t</tt>; they cannot be ordered, but can be compared for equality.
-Other processes can direct signals only to a PID, not the thread IDs within another process (TIDs of a given process have no meaning outside that process). Within the process, signals can be directed to particular TIDs. Use of <tt>raise(s)</tt> in a threaded program is equivalent to <tt>pthread_kill(pthread_self(),s)</tt>.
+Other processes can direct signals only to a PID, not the thread IDs within another process (TIDs of a given process have no meaning outside that process). Within the process, signals can be directed to particular TIDs. Use of <tt>raise(s)</tt> in a threaded program is equivalent to <tt>pthread_kill(pthread_self(), s)</tt>.
 Signal dispositions (handlers) are per-process. Signal masks are per-thread, and inherited upon thread creation (<tt>sigprocmask()</tt> is undefined in threaded programs; <tt>pthread_sigmask()</tt> must be used). Alternate signal stacks descriptors are per-thread, and inherited upon thread creation.