Re: [JDBC] JDBC broken connection against Postgres 8.4

[dmp]

>
>
>As you see below, something seems....whacked. A simple loop with an unpooled connection (code provided below) often gives an exception when connecting. The Thread.sleep statement has been made as high as 5000 ms, and exceptions still sporadically occur.
>
>I don't know if this is a JDBC driver issue or core server issue. Or something here. But the code is so simple....
>
>
>Single box test (client, server on same machine, accessing 127.0.0.1)
>Postgesql 8.4.01
>JDBC3 8.4.701 (also tried 8.3.603)
>Sun JDK 1.5_16
>Windows XP SP3, 2GB RAM, 64MB-1GB heap
>
>Code to reproduce:
>
> public static void main(String[] args) throws SQLException, InstantiationException, IllegalAccessException, ClassNotFoundException, InterruptedException {
>
> Connection con=null;
> Class.forName("org.postgresql.Driver").newInstance();
> int count=0;
> while (count < 250) {
> try {
> System.out.println(count);
> con= DriverManager.getConnection("jdbc:postgresql://localhost/retain","mjb","turnip");
> } finally {
> if (con != null) con.close();
> }
> Thread.sleep(2);
> count++;
> }
> }
>

I'm unable to reproduce the exception on a common client with the two
PostgreSQL
8.3.x database configurations, one local the other on the network,
listed below.

All linux configurations

Client:

java version "1.5.0_12"
jdbc version: "postgresql-8.3-603"

Database Hosts:

Host: 127.0.0.1
-- Generated On: 2009.08.17 AD at 09:24:16 MDT
-- SQL version: PostgreSQL 8.3.3
-- Database: world

-- Host: cindy.dandymadeproductions.net
-- Generated On: 2009.08.17 AD at 09:10:41 MDT
-- SQL version: PostgreSQL 8.3.0
-- Database: world

danap

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[jerome moliere]

2009/8/17 Michael Bell <mikeb...@yahoo.com>

I am not surprised. I strongly suspect this is an issue with Windows/PostgresSQL. OTOH, I did most of my testing against Postgres 8.4 server.

Hi all,
coul you fine tune your TCP/IP stack, trying to set a lower value for the TIME-WAIT paremeter

HTH
Jerome

--
Jerome Moliere - Mentor/J
http://romjethoughts.blogspot.com/
auteur Eyrolles

[dmp]

> As you see below, something seems....whacked. A simple loop with an
> unpooled connection (code provided below) often gives an exception
> when connecting. The Thread.sleep statement has been made as high as
> 5000 ms, and exceptions still sporadically occur.
>
> I don't know if this is a JDBC driver issue or core server issue. Or
> something here. But the code is so simple....
>
> Single box test (client, server on same machine, accessing 127.0.0.1)
> Postgesql 8.4.01
> JDBC3 8.4.701 (also tried 8.3.603)
> Sun JDK 1.5_16
> Windows XP SP3, 2GB RAM, 64MB-1GB heap
>

> Exception in thread "main" org.postgresql.util.PSQLException: The
> connection attempt failed.
> at
> org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:137)
> at
> org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:66)
> at
> org.postgresql.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:124)
> at
> org.postgresql.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:30)
> at
> org.postgresql.jdbc3.Jdbc3Connection.<init>(Jdbc3Connection.java:24)
> at org.postgresql.Driver.makeConnection(Driver.java:386)
> at org.postgresql.Driver.connect(Driver.java:260)
> at java.sql.DriverManager.getConnection(Unknown Source)
> at java.sql.DriverManager.getConnection(Unknown Source)
> at com.gwava.db.DerbyConnectionPool.main(DerbyConnectionPool.java:193)
> Caused by: java.net.SocketException: Connection reset
> at java.net.SocketInputStream.read(Unknown Source)

>
> I'm unable to reproduce the exception on a common client with the two
> PostgreSQL 8.3.x database configurations, one local the other on the
> network, listed below.
>
> All linux configurations
>
> Client:
>
> java version "1.5.0_12"
> jdbc version: "postgresql-8.3-603"
>
> Database Hosts:
>
> Host: 127.0.0.1
> -- Generated On: 2009.08.17 AD at 09:24:16 MDT
> -- SQL version: PostgreSQL 8.3.3
> -- Database: world
>
> -- Host: cindy.dandymadeproductions.net
> -- Generated On: 2009.08.17 AD at 09:10:41 MDT
> -- SQL version: PostgreSQL 8.3.0
> -- Database: world
>
> danap
>

> 2009/8/17 Michael Bell <mikeb...@yahoo.com>
>
> I am not surprised. I strongly suspect this is an issue with
> Windows/PostgresSQL. OTOH, I did most of my testing against Postgres 8.4
> server.

I'm still unable to reproduce the exception on the given configuration
when the JDBC has
been upgraded to postgresql-8.4-701.jdbc3. I will upgrade to PostgreSQL
8.4 tomorrow,
been meaning to, on one of the systems and try again. I realize you are
talking about 8.4
and what I was trying to do is provide an elimination of one or more
variables to isolate
the problem, so the experts here could focus, which I believe they may
have already done. I
also understand that mine are Linux and your is windows and you believe
there lies the possible
whack so to speak. Couple of things though:

1. The original test code you provided I believe is not doing exactly
what you think. con is never
NULL besides the first time through the loop, which the test to
close the connection is taking
place no matter whether a connection was established or not. You
always close the connection,
Suggest you try:

} finally {
if (con != null)
{
con.close();

con = null;
}

I know this is probably be nothing, but your code is just not doing
what you set it up to do.

2. If you say your connection is not pooled, why in your original
exception trace, quoted above, is:

-> at com.gwava.db.DerbyConnectionPool.main(DerbyConnectionPool.java:193)

[dmp]

> I'm still unable to reproduce the exception on the given configuration
> when the JDBC has
> been upgraded to postgresql-8.4-701.jdbc3. I will upgrade to
> PostgreSQL 8.4 tomorrow,
>

> danap.
>
> Yup.. Thanks. I tried both the 8.3 and 8.4 jdbc but only against 8.4.
> Note that a post in Feb DID go against 8.3 and he had the same issue
> (search archives for connection: reset)

Updated a server configuration today to 8.4.0. Still unable to reproduce
on a windows and
linux clients accessing server with the exact test code provided. I know
this is not your
XP/localhost configuration. I see no sense in setting up PostgreSQL on
XP for my needs
so this is all I can do to help.

Client 1, Linux:

java version "1.5.0_12"
jdbc version: "postgresql-8.4-701 JDBC3"

Client 2, XP:

java version "1.6.0"
jdbc version "postgresql-8.4-701 JDBC3"

Database Hosts:

-- Host: cindy.dandymadeproductions.com
-- Generated On: 2009.08.19 AD at 12:29:25 MDT
-- SQL version: PostgreSQL 8.4.0
-- Database: world

[Віталій Тимчишин]

May be, you have a firewall software that is working and can't keep up with all this connections opened over loopback?

2009/8/17 Michael Bell <mikeb...@yahoo.com>

[Donald Fraser]

I note from your original email that your test platform is Windows XP.
Please check the system event logs for ID 4226.
If you see this message then you have a TCP connection limit issue causing
problems.

2009/8/17 Michael Bell <mikeb...@yahoo.com>