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POHow do I get a thread ID from an arbitrary pthread_t?
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  1. POHow do I get a thread ID from an arbitrary pthread_t?
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    copied!<p>I have a pthread_t, and I'd like to change its CPU affinity. The problem is that I'm using glibc 2.3.2, which doesn't have <a href="http://www.kernel.org/doc/man-pages/online/pages/man3/pthread_setaffinity_np.3.html" rel="noreferrer">pthread_setaffinity_np()</a>. That's OK, though, because pthread_setaffinity_np() is itself a wrapper of <a href="http://linux.die.net/man/2/sched_setaffinity" rel="noreferrer">sched_setaffinity()</a>, which can be called by passing a thread ID instead of a process ID to set the affinity for an arbitrary thread.</p> <p><strong>BUT</strong> ... The thread id that sched_setaffinity can work with is an OS thread id, the kind that you can get from the <a href="http://linux.die.net/man/2/gettid" rel="noreferrer">gettid()</a> system call. <strong>This is different from the opaque type pthread_t</strong>, and gettid() will only return the thread-id of the <em>current thread</em>. I need to be able to set the CPU affinity of an arbitrary thread.</p> <p>Unfortunately, I can't access the pthread's private parts, which would let me steal the thread id by casting a pthread_t to a <code>struct pthread *</code>. All the better, I guess, since relying on private implementations is asking for even <em>more</em> trouble.</p> <p>I've also been reading up on the <a href="http://cs.pub.ro/~apc/2003/resources/pthreads/uguide/users-23.htm" rel="noreferrer">pthread_getunique_np</a> function, however this returns a "unique integral identifier" -- which I don't believe is in any way shape or form equivalent to an OS thread id.</p> <p>Hence, the question: How can I get a thread ID from an arbitrary pthread_t?</p>
 

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