sched_setaffinity fails (xtern?)

[vschiavoni]

We're getting a bunch of these in our deployment:

https://gist.github.com/vschiavoni/8a3f756604aaa6967fd481923ddc3083#file-error_log

httpd: /home/valerio/crane/xtern/obj/./../dync_hook/annotation_hooks.cpp:170: void tern_init_affinity(): Assertion 'sched_setaffinity(0, sizeof(mask), &mask) == 0' failed.
The errors are in the error_log file of apache when using the joint_sched option
The code that fails is here:

https://github.com/columbia/crane/blob/master/xtern/dync_hook/annotation_hooks.cpp#L170

Any idea of why this can happen ?