Timeout while fetching cluster config

[nitinstp23]

exit: ** (exit) exited in: GenServer.call(MyApp.ElasticsearchCluster, :config, 5000)
    ** (EXIT) time out
  File "lib/gen_server.ex", line 836, in GenServer.call/3
  File "lib/elasticsearch.ex", line 307, in Elasticsearch.post/4

We get this error randomly in our app while making GET/POST requests to Elasticsearch.

Elasticsearch.post/4 calls Elasticsearch .Cluster.Config.get(cluster) here

And the cluster config is found via this - https://github.com/danielberkompas/elasticsearch-elixir/blob/master/lib/elasticsearch/cluster/cluster.ex#L172

Given the cluster is a GenServer and this call GenServer.call/3 can timeout since a single process can get overloaded under heavy load.

Can we move the :api out of the cluster config and the user can pass the Elasticsearch.API behaviour module to functions like Elasticsearch.get, Elasticsearch.post, etc?

@danielberkompas Let me know your thoughts.

[danielberkompas]

It does seem like cutting out the GenServer.call would be beneficial here. My encryption library Cloak handles this by saving the config to an ETS table and then reading it out of the ETS table in a function, rather than via GenServer. Perhaps this could serve as a pattern to fix the issue?

https://github.com/danielberkompas/cloak/blob/master/lib/cloak/vault.ex#L274-L292

[nitinstp23]

@danielberkompas Yes, saving the config in an ETS table will definitely help here. I'll try to send a PR soon!