Re: Memory leak or client side caching? - Mailing list pgsql-jdbc

From Roland Walter
Subject Re: Memory leak or client side caching?
Date
Msg-id rc4ace2kep3.fsf@mosaic-ag.com
Whole thread Raw
In response to Memory leak or client side caching?  (Kovács Péter <peter.kovacs@chemaxon.hu>)
List pgsql-jdbc
Kovács Péter <peter.kovacs@chemaxon.hu> writes:

> Hi,
>
> Executing the following code results in an increase of 1GB in memory
> usage by the process.
>
> String sql = "SELECT
>
cd_id,cd_fp1,cd_fp2,cd_fp3,cd_fp4,cd_fp5,cd_fp6,cd_fp7,cd_fp8,cd_fp9,cd_fp10,cd_fp11,cd_fp12,cd_fp13,cd_fp14,cd_fp15,cd_fp16,cd_smiles
> FROM editexample1";
> PreparedStatement ps = conn.prepareStatement(sql);
> try {
>     ResultSet rs = ps.executeQuery();
>     try {
>         while (rs.next()) {
>             int cdId = rs.getInt(1);
>             for (int i = 0; i < 16; i++) {
>                 int fp = rs.getInt(i+2);
>             }
>             String cdSmiles = rs.getString(18);
>         }
>     } finally {
>         rs.close();
>     }
> } finally {
>     ps.close();
> }
>
> The result set contains 1 250 000 rows.
>
> I am not sure if this is a memory leak or the driver just caches the
> result set on the client side. If this is the latter, is there a way
> to turn off client side caching? If the former, how should I proceed
> to find the problem?
>

If you do not use a cursor, the ResultSet tries to load all rows
into the memory.

Before executing the query you should set autocommit to false and
set the fetchsize on the PreparedStatement to the maximal count
of rows that are loaded into the memory:

   con.setAutoCommit(false);
   ps.setFetchSize(1000);


--
Roland Walter                   mailto: rwa (at) mosaic-ag (dot) com
MOSAIC SOFTWARE AG               phone: +49 (0) 22 25 / 88 2-41 1
Am Pannacker 3                     fax: +49 (0) 22 25 / 88 2-20 1
D-53340 Meckenheim                http://www.mosaic-ag.com


Die in dieser E-Mail enthaltenen Nachrichten und Anhaenge sind ausschliesslich
fuer den bezeichneten Adressaten bestimmt. Sie koennen rechtlich geschuetzte,
vertrauliche Informationen enthalten. Falls Sie nicht der bezeichnete Empfaenger
oder zum Empfang dieser E-Mail nicht berechtigt sind, ist die Verwendung,
Vervielfaeltigung oder Weitergabe von Nachrichten und Anhaengen untersagt.
Falls Sie diese E-Mail irrtuemlich erhalten haben, informieren Sie bitte
unverzueglich den Absender und vernichten Sie die E-Mail.

This e-mail message and any attachment are intended exclusively for the named
addressee. They may contain confidential information which may also be protected
by professional secrecy. Unless you are the named addressee (or authorised to
receive for the addressee) you may not copy or use this message or any attachment
or disclose the contents to anyone else. If this e-mail was sent to you by mistake
please notify the sender immediately and delete this e-mail.


pgsql-jdbc by date:

Previous
From: Kovács Péter
Date:
Subject: Memory leak or client side caching?
Next
From: Kris Jurka
Date:
Subject: Re: cannot dollar-quote $$?$$ in PreparedStatements