Attempts to drain the queue of tasks for release history data to fetch.
function _update_fetch_data() {
$queue = DrupalQueue::get('update_fetch_tasks');
$end = time() + variable_get('update_max_fetch_time', UPDATE_MAX_FETCH_TIME);
while (time() < $end && ($item = $queue
->claimItem())) {
_update_process_fetch_task($item->data);
$queue
->deleteItem($item);
}
}