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From "Damien Katz (Commented) (JIRA)" <>
Subject [jira] [Commented] (COUCHDB-1342) Asynchronous file writes
Date Thu, 17 Nov 2011 18:53:51 GMT


Damien Katz commented on COUCHDB-1342:

Robert, the inflight batching of writes is limited to 1 meg per database. we've not seen it
increase memory usage, but the code is written such that it could be made configurable to
smaller max batch size. If we are concerned, this is a detail I'd like to see addressed post
> Asynchronous file writes
> ------------------------
>                 Key: COUCHDB-1342
>                 URL:
>             Project: CouchDB
>          Issue Type: Improvement
>          Components: Database Core
>            Reporter: Jan Lehnardt
>             Fix For: 1.3
>         Attachments: COUCHDB-1342.patch
> This change updates the file module so that it can do
> asynchronous writes. Basically it replies immediately
> to process asking to write something to the file, with
> the position where the chunks will be written to the
> file, while a dedicated child process keeps collecting
> chunks and write them to the file (and batching them
> when possible). After issuing a series of write request
> to the file module, the caller can call its 'flush'
> function which will block the caller until all the
> chunks it requested to write are effectively written
> to the file.
> This maximizes the IO subsystem, as for example, while
> the updater is traversing and modifying the btrees and
> doing CPU bound tasks, the writes are happening in
> parallel.
> Originally described at
> Github Commit:

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