Mike Wallace created COUCHDB-2425:
-------------------------------------
Summary: Exceptions in couch_proc_manager:new_proc/1 leave
dangling couch_query_servers
Key: COUCHDB-2425
URL: https://issues.apache.org/jira/browse/COUCHDB-2425
Project: CouchDB
Issue Type: Bug
Security Level: public (Regular issues)
Components: Database Core
Reporter: Mike Wallace
If an exception is thrown in the try blocks in either of the
couch_proc_manager:new_proc/1 clauses [1] [2] then a spawn_error is returned
which is handled by a specific handle_info clause [3] which does not reply to
the calling process. When the caller is couch_query_servers:get_os_process/1
[4] there is an infinite timeout so that process will hang around until either
the node reboots or someone intervenes.
The user-facing symptom is an entry in _active_tasks that makes no progress and
never goes away.
The easiest way to reproduce this is to create a new view and then patch the
code to force an exception in the appropriate place, e.g.: (assuming a live
dev/run instance):
1. Create DB, add a ddoc and a doc:
{code}
$ curl -X PUT http://localhost:15984/kitteh
{"ok":true}
$ curl -X POST http://localhost:15984/kitteh -d '{"_id":"_design/view",
"views": {"test": {"map": "function(doc) { emit(doc.id, 1); }"}}}' -H
'Content-Type: application/json'
{"ok":true,"id":"_design/view","rev":"1-ef10f980522d4c8e691e3c26d4c3fac5"}
$ curl -X PUT http://localhost:15984/kitteh/ohai -d '{}'
{"ok":true,"id":"ohai","rev":"1-967a00dff5e02add41819138abb3284d"}
{code}
2. Apply https://gist.github.com/mikewallace1979/79f823da25f6a78e2725 then
re-run make and dev/run.
3. Attempt to query the view:
{code}
$ curl -X GET http://localhost:15984/kitteh/_design/view/_view/test
{"error":"timeout","reason":"The request could not be processed in a reasonable
amount of time."}
{code}
4. Observe index build tasks which never go away:
{code}
$ curl -X GET http://localhost:15986/_active_tasks
[{"pid":"<0.2403.0>","changes_done":0,"database":"shards/40000000-5fffffff/kitteh.1414779043","design_document":"_design/view","progress":0,"started_on":1414779439,"total_changes":1,"type":"indexer","updated_on":1414779439},{"pid":"<0.2444.0>","changes_done":0,"database":"shards/00000000-1fffffff/kitteh.1414779043","design_document":"_design/view","progress":0,"started_on":1414779439,"total_changes":1,"type":"indexer","updated_on":1414779439}]
{code}
[1]
https://github.com/apache/couchdb-couch/blob/master/src/couch_query_servers.erl#L354
[2]
https://github.com/apache/couchdb-couch/blob/master/src/couch_proc_manager.erl#L368-L384
[3]
https://github.com/apache/couchdb-couch/blob/master/src/couch_proc_manager.erl#L239-L245
[4]
https://github.com/apache/couchdb-couch/blob/master/src/couch_query_servers.erl#L354
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
