Downtime for one of nodes with memcached causes delays in Horizon

[Vlad Okhrimenko]

Horizon uses memcached servers for caching and it connects to all of them directly. So if one of them is not responding, it may lead to delays in Horizon operations.

Workaround:

1) Edit /etc/openstack-dashboard/local_settings file and temporarily remove the problem controller IP:PORT from LOCATION line in CACHE structure:

CACHES = {
    'default': {
        'BACKEND' : 'django.core.cache.backends.memcached.MemcachedCache',
        'LOCATION' : "127.0.0.3:11211;127.0.0.5:11211;127.0.0.6:11211"
    },

2) Restart apache web server

For reproduce:

sudo apt-get install memcached
pip install python-memcache (in venv)

in local_settings:

CACHES = {
    'default': {
        'BACKEND' : 'django.core.cache.backends.memcached.MemcachedCache',
        'LOCATION' : "127.0.0.1:11211"
    },

after this memcache works good, then set 'LOCATION' to "127.0.0.0:11211" -- we get large delay time

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/171679

[OpenStack Infra (hudson-openstack)]

Change abandoned by Rob Cresswell (<email address hidden>) on branch: master
Review: https://review.openstack.org/171679
Reason: Abandoning for now, hasn't been updated in 3 months. Feel free to restore and update if you get time to work on the patch. Thanks!

[OpenStack Infra (hudson-openstack)]

Change abandoned by Ivan Kolodyazhny (<email address hidden>) on branch: master
Review: https://review.openstack.org/171679
Reason: This review is > 4 months without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.