The gfarm_url_hosts_schedule() function schedules filesystem
nodes using file-affinity scheduling with a Gfarm file
gfarm_url, and returns an array of filesystem hostnames
hostsp and the number of scheduled hosts nhostsp. The
returned array of hostnames hostsp should be free'ed with
The function terminated successfully.
Insufficient memory was available.
An error except the above occurred. The reason is shown by its
is reserved to specify options for scheduling, although it is not used
in the current implementation.