Mailing-List: contact derby-dev-help@db.apache.org; run by ezmlm
Precedence: bulk
Reply-To: <derby-dev@db.apache.org>
Message-ID: <24624043.1163544399052.JavaMail.jira@brutus>
Date: Tue, 14 Nov 2006 14:46:39 -0800 (PST)
From: "Suresh Thalamati (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Commented: (DERBY-801) Allow parallel access to data files.
In-Reply-To: <379656011.1136803530096.JavaMail.jira@ajax.apache.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable

    [ http://issues.apache.org/jira/browse/DERBY-801?page=3Dcomments#action=
_12449848 ]=20
           =20
Suresh Thalamati commented on DERBY-801:
----------------------------------------

Hi Anders,=20

I agree with Knut,  this issue can be marked as fixed,   Thanks a lot for  =
working on this improvement.=20

-suresh


> Allow parallel access to data files.
> ------------------------------------
>
>                 Key: DERBY-801
>                 URL: http://issues.apache.org/jira/browse/DERBY-801
>             Project: Derby
>          Issue Type: Improvement
>          Components: Performance, Store
>    Affects Versions: 10.0.2.0, 10.0.2.1, 10.1.1.0, 10.1.2.1
>         Environment: Any
>            Reporter: =C3=98ystein Gr=C3=B8vlen
>         Assigned To: Anders Morken
>             Fix For: 10.3.0.0
>
>         Attachments: DERBY-801-6.patch, DERBY-801-7.patch, DERBY-801-v2.p=
atch, DERBY-801-v3.patch, DERBY-801-v4.patch, DERBY-801-v5.patch, NIO-RAFCo=
ntainer-v1.patch
>
>
> Derby currently serializes accesses to a data file.  For example, the
> implementation of RAFContainer.readPage is as follows:
>     synchronized (this) {  // 'this' is a FileContainer, i.e. a file obje=
ct
>         fileData.seek(pageOffset);  // fileData is a RandomAccessFile
>         fileData.readFully(pageData, 0, pageSize);
>     }
> I have experiemented with a patch where I have introduced several file
> descriptors (RandomAccessFile objects) per RAFContainer.  These are
> used for reading.  The principle is that when all readers are busy, a
> readPage request will create a new reader.  (There is a maximum number
> of readers.)  With this patch, throughput was improved by 50% on
> linux.  For more discussion on this, see
> http://www.nabble.com/Derby-I-O-issues-during-checkpointing-t473523.html
> The challenge with the suggested approach is to make a mechanism to
> limit the number of open file descpriptors.  Mike Matrigali has
> suggested to use the existing CacheManager infrastructure for this
> purpose.  For a discussion on that, see:
> http://www.nabble.com/new-uses-for-basic-services-cache---looking-for-adv=
ice-t756863.html

--=20
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators: htt=
p://issues.apache.org/jira/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira