[jira] Updated: (COUCHDB-487) Pause write requests to allow compaction to complete

["Paul Joseph Davis (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/COUCHDB-487?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paul Joseph Davis updated COUCHDB-487:
--------------------------------------

    Skill Level: Committers Level (Medium to Hard)

> Pause write requests to allow compaction to complete
> ----------------------------------------------------
>
>                 Key: COUCHDB-487
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-487
>             Project: CouchDB
>          Issue Type: Improvement
>          Components: Database Core
>            Reporter: Robert Newson
>         Attachments: block_writes_after_end_of_compaction.patch
>
>
> Continuous writes will currently indefinitely prevent the compaction process from flipping over to the .compact file.
> Here's a small patch that adds a new db flag called 'write_available' which becomes false the first time compaction completes but fails to flip over because of concurrent writes. Subsequent calls to update_docs then sleep for 1/2 a second and throw retry.
> I ran 'ab -p json -n 1000000 http://localhost:5984/db1' in one window. Without this patch, I get a long sequence of;
> [info] [<0.64.0>] Compaction file still behind main file (update seq=1848. compact update seq=1845). Retrying.
> and compaction never completes.
> With the patch, I get this;
> [info] [<0.369.0>] 127.0.0.1 - - 'POST' /db1 201
> [info] [<0.65.0>] Compaction file still behind main file (update seq=2140. compact update seq=2092). Retrying.
> [info] [<0.65.0>] Blocking writes to complete compaction.
> [info] [<0.65.0>] Compaction for db "db1" completed.
> [info] [<0.370.0>] 127.0.0.1 - - 'POST' /db1 201

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