Comment 0 for bug 1252659

Hi.

An empty file CONF.instances_path/compute_nodes is causing the following
error. This prevents the image cache manager to run (i do not know if it has
some other consequences):

    INFO nova.compute.resource_tracker [-] Compute_service record updated for cmshp11.ifca.es:cmshp11.ifca.es
    ERROR nova.openstack.common.periodic_task [-] Error during ComputeManager._run_image_cache_manager_pass: No JSON object could be decoded
    TRACE nova.openstack.common.periodic_task Traceback (most recent call last):
    TRACE nova.openstack.common.periodic_task File "/usr/lib/python2.7/dist-packages/nova/openstack/common/periodic_task.py", line 180, in run_periodic_tasks
    TRACE nova.openstack.common.periodic_task task(self, context)
    TRACE nova.openstack.common.periodic_task File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 5040, in _run_image_cache_manager_pass
    TRACE nova.openstack.common.periodic_task storage_users.register_storage_use(CONF.instances_path, CONF.host)
    TRACE nova.openstack.common.periodic_task File "/usr/lib/python2.7/dist-packages/nova/virt/storage_users.py", line 65, in register_storage_use
    TRACE nova.openstack.common.periodic_task return do_register_storage_use(storage_path, hostname)
    TRACE nova.openstack.common.periodic_task File "/usr/lib/python2.7/dist-packages/nova/openstack/common/lockutils.py", line 246, in inner
    TRACE nova.openstack.common.periodic_task return f(*args, **kwargs)
    TRACE nova.openstack.common.periodic_task File "/usr/lib/python2.7/dist-packages/nova/virt/storage_users.py", line 58, in do_register_storage_use
    TRACE nova.openstack.common.periodic_task d = json.loads(f.read())
    TRACE nova.openstack.common.periodic_task File "/usr/lib/python2.7/json/__init__.py", line 328, in loads
    TRACE nova.openstack.common.periodic_task return _default_decoder.decode(s)
    TRACE nova.openstack.common.periodic_task File "/usr/lib/python2.7/json/decoder.py", line 365, in decode
    TRACE nova.openstack.common.periodic_task obj, end = self.raw_decode(s, idx=_w(s, 0).end())
    TRACE nova.openstack.common.periodic_task File "/usr/lib/python2.7/json/decoder.py", line 383, in raw_decode
    TRACE nova.openstack.common.periodic_task raise ValueError("No JSON object could be decoded")
    TRACE nova.openstack.common.periodic_task ValueError: No JSON object could be decoded
    TRACE nova.openstack.common.periodic_task