Makara::Errors::AllConnectionsBlacklisted

[nikhilvs]

Issue looks like similar to #36 , but in our case we are not stopping any of our slave or master database.

Stack trace from new relic is as follows :

….1/bundler/gems/makara-1ac718c7650c/lib/makara/
pool.rb: 95:in provide' …1/bundler/gems/makara-1ac718c7650c/lib/makara/ proxy.rb: 69:inmethod_missing'
/usr/lib/ruby/1.9.1/
monitor.rb: 211:in mon_synchronize' /usr/lib/ruby/1.9.1/ monitor.rb: 211:inmon_synchronize'
…_adapters/abstract/
connection_specification_changes.rb: 47:in retrieve_connection' …_adapters/abstract/ connection_specification_changes.rb: 29:inconnection'

What might have gone wrong in this case ?

Environment details
makara version : 'v0.2.2'
Rails version : 3.2.14
Ruby version : ruby 1.9.3p484

[mnelson]

That error occurs when all connections had a failure related to connectivity within the blacklist duration. If you weren't using makara, it would be equivalent to seeing a connection error in newrelic. Are you able to provide the full trace and a summary of your database.yml?

[nikhilvs]

Our database.yml looks like this :

  adapter: 'makara_mysql2'
  encoding: utf8
  database: <%= ENV['RDS_DB_NAME'] %>
  username: <%= ENV['RDS_USERNAME'] %>
  password: <%= ENV['RDS_PASSWORD'] %>
  host: <%= ENV['RDS_HOSTNAME'] %>
  port: <%= ENV['RDS_PORT'] %>
  pool: <%= ENV['DB_POOL'] %>
  reaping_frequency: <%= ENV['REAPING_FREQUENCY'] %>
  timeout: 5000

  makara:
    blacklist_duration: 5
    master_ttl: 5
    sticky: true
    rescue_connection_failures: false

    connections:
      - role: master
        host: <%= ENV['RDS_HOSTNAME'] %>
        name: master-database
      - role: slave
        host: <%= ENV['DB_SLAVE1'] %>
        name: read-slave1
        weight: 5
      - role: slave
        host: <%= ENV['DB_SLAVE2'] %>
        name: read-slave2
        weight: 5

[joelr]

I get the same error when I only have one connection defined in the connection list, even when the connection is valid...

eg

    connections:
      - role: master
        host: <%= ENV['DATABASE_HOST'] %>
        adapter: mysql2
<% unless ENV['DATABASE_SLAVE_HOST'].blank? %>
      - role: slave
        host: <%= ENV['DATABASE_SLAVE_HOST'] %>
        adapter: mysql2
        database: <%= ENV['DATABASE_SLAVE_DATABASE'] %>
        username: <%= ENV['DATABASE_SLAVE_USERNAME'] %>
        password: <%= ENV['DATABASE_SLAVE_PASSWORD'] %>
<% end %>

I wanted the slave to be optional, but it seems to fail with Makara::Errors::AllConnectionsBlacklisted unless > 1 connection is defined, is this a known issue?

[ic]

Same problem as @joelr. It would be great if Makara could behave as a "standard" adapter when there is only a master defined.

One practical example is to set up a staging environment with the same adapter as production (i.e. Makara), but with only a single DB for saving cost. This allows to test easily (except, yes, this settings does not allow to test fail-overs!).

@joelr: One dangerous workaround is to set a single machine as both master and slave. I did not check the source code yet, so please be aware this should be temporary (or confirmed as an OK workaround). A brief look at pool.rb tells me that it should be ok, but pretty costly (e.g. each send_to_all is executed twice by the DB, etc).

[bleonard]

I'm going to combine this with this one (#101) -- I think they are both saying that master is special and especially if there is only one, there is something interesting that should happen where it works like "normal" - more investigating on that that means but "merging" them.