Constantly getting errors when querying views: "The request could not be processed in a reasonable amount of time"

[lokedhs]

Current Behavior

On certain databases, every request to a view results in the same error:

{"error":"timeout","reason":"The request could not be processed in a reasonable amount of time.","ref":181479430}

The CouchDB instance contains three databases. Originally, the problem was intermittent but it increased in frequency until every single view request resulted in a timeout.

After dumping the databases and reinstalling CouchDB, everything seemed to work, but after a few hours any view requests on one of the databases again results in the same error. There may be still intermittent errors on the other databases.

Doing a GET on /_active_tasks always returns the empty list.

Relevant messages from the log:

couchdb_1            | [error] 2018-04-30T11:27:45.740408Z nonode@nohost <0.1343.9> 176ec499d3 req_err(181479430) timeout : The request could not be processed in a reasonable amount of time.
couchdb_1            |     [<<"gen_server:call/3 L190">>,<<"couch_query_servers:get_os_process/1 L495">>,<<"couch_query_servers$os_rereduce/3 L134">>,<<"lists:zipwith/3 L449">>,<<"couch_query_servers:rereduce/3 L93">>,<<"fabric_view:get_next_row/1 L232">>$<<"fabric_view:maybe_send_row/1 L128">>,<<"rexi_utils:process_mailbox/6 L55">>]
couchdb_1            | [notice] 2018-04-30T11:27:45.749100Z nonode@nohost <0.1343.9> 176ec499d3 couchdb:5984 172.18.0.10 undefi$ed GET /potato-notification/_design/user/_view/notifications_updated?endkey=%222018-04-30T11%3A27%3A40.730485Z%22 500 ok 5017
couchdb_1            | [error] 2018-04-30T11:27:46.986409Z nonode@nohost emulator -------- Error in process <0.1562.9> with exit value: {database_does_not_exist,[{mem3_shards,load_shards_from_db,"_users",[{file,"src/mem3_shards.erl"},{line,403}]},{mem3_shards,load_shards_from_disk,1,[{file,"src/mem3_shards.erl"},{line,378}]},{mem3_shards,load_shards_from_disk... 
couchdb_1            | [notice] 2018-04-30T11:27:46.986570Z nonode@nohost <0.509.0> -------- chttpd_auth_cache changes listener died database_does_not_exist at mem3_shards:load_shards_from_db/6(line:403) <= mem3_shards:load_shards_from_disk/1(line:378) <= mem3_shards:load_shards_from_disk/2(line:407) <= mem3_shards:for_docid/3(line:91) <= fabric_doc_open:go/3(line:38) <= chttpd_auth_cache:ensure_auth_ddoc_exists/2(line:187) <= chttpd_auth_cache:listen_for_changes/1(line:134)
couchdb_1            | [error] 2018-04-30T11:27:51.758412Z nonode@nohost <0.1502.9> 03a1542fcc req_err(181479430) timeout : The request could not be processed in a reasonable amount of time.
couchdb_1            |     [<<"gen_server:call/3 L190">>,<<"couch_query_servers:get_os_process/1 L495">>,<<"couch_query_servers:os_rereduce/3 L134">>,<<"lists:zipwith/3 L449">>,<<"couch_query_servers:rereduce/3 L93">>,<<"fabric_view:get_next_row/1 L232">>,<<"fabric_view:maybe_send_row/1 L128">>,<<"rexi_utils:process_mailbox/6 L55">>]
couchdb_1            | [notice] 2018-04-30T11:27:51.766405Z nonode@nohost <0.1502.9> 03a1542fcc couchdb:5984 172.18.0.10 undefined GET /potato-notification/_design/user/_view/notifications_updated?endkey=%222018-04-30T11%3A27%3A46.748789Z%22 500 ok 5016


## Steps to Reproduce (for bugs)

I don't have a generic way to reproduce, other than loading the current production database and running our application for a while. I can't share this database, but I'll be happy to run any tests required.

## Your Environment

CouchDB 2.1.1 installed via the official Docker image.
The application used: https://github.com/cicakhq/potato

[wohali]

Your container needs more CPU. Views are calculated by secondary processes (couchjs) which are not getting enough time to execute on its own.

Allocate more CPU cores to the docker instance.

Duplicate of #1298 #1297