Re: [DBCP] Anther lame pool exhausted exception question
Hi Brian,
Examples can be found here:
http://svn.apache.org/repos/asf/jakarta/commons/proper/dbcp/trunk/doc/
If you are creating a BasicDataSource yourself then you need to keep it
in a static variable somewhere. You create it once and only close the
datasource when your application is shutting down. The BasicDataSource
contains the pool and you only want one of these around for each
database(scheme) you want to connect to.
Your program then uses ds.getConnection() / conn.close() to get/return
connections from/to the pool.
Use the pattern Craig gave you to make sure you always close the
rs/stmt/conn.
So key point here is to only create one datasource (and store it in a
static somewhere) and not to close the datasource after each call.
Cheers
Dirk
Brian Cook wrote:
I have several apps written that use org.apache.commons.dbcp. And I am
getting the org.apache.commons.dbcp.SQLNestedException: Cannot get a
connection, pool exhausted exception.
When I run netstat sure enough it shows about 60 - 100 ESTABLISHED
connections open at any given time. Looking deeper it looks like new
connections are created most but not each time the Java Bean the uses
the data base is called. So it seems pretty clear that I am failing to
close all of the connections in my app. My problem is that I can not
find where that is.
My understanding is that as long as I close every ResultSet, and each
Connection object I should have my bases covered. I have gone back
though the app repeatedly and verified that all the ResultSets,
Connections, and BasicDataSource objects are all being closed.
Due to an internal political problem I am not using JNDI for the
connections. Instead I have a class file that is called when a
connection is need. After the object is used a close() method is called
and closes the Statement, Connection, ResultSet, BasicDataSource objects.
So my questions are ..
1. Is there something else I should be doing to return the
connections to the pool?
2. Does not using JNDI with org.apache.commons.dbcp cause problems
with closing the connection pool some how?
I have been though about 6 months of the archives for this list and did
not find any hints, I went to look at the examples lnik at on the
Commons.DBCP page but the link to
http://cvs.apache.org/downviewcvs.html/jakarta-commons/dbcp/doc/ seems
to be broken. Googling has only just returned the usall advice of make
sure you are closing every connection.
I am open to any ideas or thoughts to what I am failing to due here.
Details and the code are included below.
OS: Linux Red Hat 9.0
Container: Tomcat 4.127
DBCP:commons-dbcp-1.2.1.jar, commons-pool-1.2.jar
JDK: 1.5
Database:MySQL 4.1
JDBC Driver: mysql-connector-java-3.1.7-bin.jar
public class DBConector {
Omited Code/
public DBConector(String dataBaseName) {
try{
String DataBaseURL = jdbc:mysql://+DataBaseHost+/+dataBaseName+
?user=+DataBaseUser+password=+DataBasePassword;
mysqlCon = getPooledConection(DataBaseURL);
sqlStatement = mysqlCon.createStatement();
}
catch(Exception s) {
System.err.println(new java.util.Date()+ Error throw by +
DBConector()\n+s);
}
}
Omited Code/
public ResultSet read(String SQL) {
try{
rs = sqlStatement.executeQuery( SQL );
} // Close try
catch(Exception s) {
System.err.println(new java.util.Date()+ Error throw by an
SQL +
call in DBConector.read() class : \n+s+\n+s.getMessage()+
\nSQL Queary : +SQL+\n);
} // Close catch
return(DataFromDB);
} // Close the read method
Omited Code/
protected static Connection getPooledConection(String connectURI) {
ds = new BasicDataSource();
ds.setDriverClassName(DBDriver);
ds.setUsername(DataBaseUser);
ds.setPassword(DataBasePassword);
ds.setUrl(connectURI);
ds.setInitialSize(3);
ds.setMaxActive(32);
ds.setMaxIdle(8);
ds.setMinIdle(3);
Connection con = null;
try {
con = ds.getConnection();
}
catch(Exception a){System.out.println(new java.util.Date() +
PrintTimeDataBase6.getPooledConection() has thrown an
exception.\n+a+
\n+ a.getMessage() );
}
return con;
} // Close method
Omited Code/
public void close() {
try { sqlStatement.close(); } catch(Exception a) { }
try { mysqlCon.close(); } catch(Exception a) { }
try { rs.close(); } catch(Exception a) { }
try { ds.close(); } catch(Exception a) { }
}// Close method
} // Close the PrintTimeWebServices Class
Re: [DBCP] Anther lame pool exhausted exception question
Ding Ding Ding. We have a winner. That is exactly what I am doing
wrong. A new BasicDataSource is created every time a Java Bean is
called. I guess that also explains why I am seeing 60 - 100 active
connections in netstat when the maxActive value was set to 32.
I will look into using JNDI and or have a servlet that runs continually
in the background.
Thanks to everyone who responded the ideas provided are great. You guys
rock!
Dirk Verbeeck wrote:
Hi Brian,
Examples can be found here:
http://svn.apache.org/repos/asf/jakarta/commons/proper/dbcp/trunk/doc/
If you are creating a BasicDataSource yourself then you need to keep it
in a static variable somewhere. You create it once and only close the
datasource when your application is shutting down. The BasicDataSource
contains the pool and you only want one of these around for each
database(scheme) you want to connect to.
Your program then uses ds.getConnection() / conn.close() to get/return
connections from/to the pool.
Use the pattern Craig gave you to make sure you always close the
rs/stmt/conn.
So key point here is to only create one datasource (and store it in a
static somewhere) and not to close the datasource after each call.
Cheers
Dirk
Brian Cook wrote:
I have several apps written that use org.apache.commons.dbcp. And I
am getting the org.apache.commons.dbcp.SQLNestedException: Cannot get
a connection, pool exhausted exception.
When I run netstat sure enough it shows about 60 - 100 ESTABLISHED
connections open at any given time. Looking deeper it looks like new
connections are created most but not each time the Java Bean the uses
the data base is called. So it seems pretty clear that I am failing
to close all of the connections in my app. My problem is that I can
not find where that is.
My understanding is that as long as I close every ResultSet, and each
Connection object I should have my bases covered. I have gone back
though the app repeatedly and verified that all the ResultSets,
Connections, and BasicDataSource objects are all being closed.
Due to an internal political problem I am not using JNDI for the
connections. Instead I have a class file that is called when a
connection is need. After the object is used a close() method is
called and closes the Statement, Connection, ResultSet,
BasicDataSource objects.
So my questions are ..
1. Is there something else I should be doing to return the
connections to the pool?
2. Does not using JNDI with org.apache.commons.dbcp cause problems
with closing the connection pool some how?
I have been though about 6 months of the archives for this list and
did not find any hints, I went to look at the examples lnik at on
the Commons.DBCP page but the link to
http://cvs.apache.org/downviewcvs.html/jakarta-commons/dbcp/doc/ seems
to be broken. Googling has only just returned the usall advice of
make sure you are closing every connection.
I am open to any ideas or thoughts to what I am failing to due here.
Details and the code are included below.
OS: Linux Red Hat 9.0
Container: Tomcat 4.127
DBCP:commons-dbcp-1.2.1.jar, commons-pool-1.2.jar
JDK: 1.5
Database:MySQL 4.1
JDBC Driver: mysql-connector-java-3.1.7-bin.jar
public class DBConector {
Omited Code/
public DBConector(String dataBaseName) {
try{
String DataBaseURL =
jdbc:mysql://+DataBaseHost+/+dataBaseName+
?user=+DataBaseUser+password=+DataBasePassword;
mysqlCon = getPooledConection(DataBaseURL);
sqlStatement = mysqlCon.createStatement();
}
catch(Exception s) {
System.err.println(new java.util.Date()+ Error throw by +
DBConector()\n+s);
}
}
Omited Code/
public ResultSet read(String SQL) {
try{
rs = sqlStatement.executeQuery( SQL );
} // Close try
catch(Exception s) {
System.err.println(new java.util.Date()+ Error throw by an
SQL +
call in DBConector.read() class : \n+s+\n+s.getMessage()+
\nSQL Queary : +SQL+\n);
} // Close catch
return(DataFromDB);
} // Close the read method
Omited Code/
protected static Connection getPooledConection(String connectURI) {
ds = new BasicDataSource();
ds.setDriverClassName(DBDriver);
ds.setUsername(DataBaseUser);
ds.setPassword(DataBasePassword);
ds.setUrl(connectURI);
ds.setInitialSize(3);
ds.setMaxActive(32);
ds.setMaxIdle(8);
ds.setMinIdle(3);
Connection con = null;
try {
con = ds.getConnection();
}
catch(Exception a){System.out.println(new java.util.Date() +
PrintTimeDataBase6.getPooledConection() has thrown an
exception.\n+a+
\n+ a.getMessage() );
}
return con;
}
Re: [DBCP] Anther lame pool exhausted exception question
The key to returning connections to the connection pool is to call
close() on the *connection* itself. The most common way people get
themselves in trouble is to skip this somehow (perhaps because an
exception is thrown).
To avoid that sort of problem, I tend to use an idiom like this for
JDBC access code:
DataSource ds = ...; // Acquire a reference from JNDI or wherever
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try {
conn = ds.getConnection(); // Or whatever
stmt = conn.prepareStatement(...);
rs = stmt.executeQuery();
... process the results ...
} catch (SQLException e) {
... process the exception ...
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
... record or ignore ...
}
rs = null;
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
... record or ignore ...
}
rs = null;
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
... record or ignore ...
}
conn = null;
}
}
Courtesy of the finally logic, I'm guaranteed to always execute my
cleanup code, no matter where an exception might get thrown.
You'll note that it can be pretty tedious to do all this stuff with
raw JDBC. You might also want to look at using one of the SQL
frameworks that encapsulate this sort of stuff, but still give you the
guarantee that the connection will ultimately be returned to the pool.
Craig
On 7/14/05, Brian Cook [EMAIL PROTECTED] wrote:
I have several apps written that use org.apache.commons.dbcp. And I am
getting the org.apache.commons.dbcp.SQLNestedException: Cannot get a
connection, pool exhausted exception.
When I run netstat sure enough it shows about 60 - 100 ESTABLISHED
connections open at any given time. Looking deeper it looks like new
connections are created most but not each time the Java Bean the uses
the data base is called. So it seems pretty clear that I am failing to
close all of the connections in my app. My problem is that I can not
find where that is.
My understanding is that as long as I close every ResultSet, and each
Connection object I should have my bases covered. I have gone back
though the app repeatedly and verified that all the ResultSets,
Connections, and BasicDataSource objects are all being closed.
Due to an internal political problem I am not using JNDI for the
connections. Instead I have a class file that is called when a
connection is need. After the object is used a close() method is called
and closes the Statement, Connection, ResultSet, BasicDataSource objects.
So my questions are ..
1. Is there something else I should be doing to return the
connections to the pool?
2. Does not using JNDI with org.apache.commons.dbcp cause problems
with closing the connection pool some how?
I have been though about 6 months of the archives for this list and did
not find any hints, I went to look at the examples lnik at on the
Commons.DBCP page but the link to
http://cvs.apache.org/downviewcvs.html/jakarta-commons/dbcp/doc/ seems
to be broken. Googling has only just returned the usall advice of make
sure you are closing every connection.
I am open to any ideas or thoughts to what I am failing to due here.
Details and the code are included below.
OS: Linux Red Hat 9.0
Container: Tomcat 4.127
DBCP:commons-dbcp-1.2.1.jar, commons-pool-1.2.jar
JDK: 1.5
Database:MySQL 4.1
JDBC Driver: mysql-connector-java-3.1.7-bin.jar
public class DBConector {
Omited Code/
public DBConector(String dataBaseName) {
try{
String DataBaseURL = jdbc:mysql://+DataBaseHost+/+dataBaseName+
?user=+DataBaseUser+password=+DataBasePassword;
mysqlCon = getPooledConection(DataBaseURL);
sqlStatement = mysqlCon.createStatement();
}
catch(Exception s) {
System.err.println(new java.util.Date()+ Error throw by +
DBConector()\n+s);
}
}
Omited Code/
public ResultSet read(String SQL) {
try{
rs = sqlStatement.executeQuery( SQL );
} // Close try
catch(Exception s) {
System.err.println(new java.util.Date()+ Error throw by an
SQL +
call in DBConector.read() class : \n+s+\n+s.getMessage()+
\nSQL Queary : +SQL+\n);
} // Close catch
return(DataFromDB);
} // Close the read method
Omited Code/
protected static Connection
RE: [DBCP] Anther lame pool exhausted exception question
Hello.
Maybe you can use DbUtils class from dbutils project to code less in the finally
clause; methods closeQuietly and close makes this tedious stuff easier.
DataSource ds = ...; // Acquire a reference from JNDI or wherever
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try {
conn = ds.getConnection(); // Or whatever
stmt = conn.prepareStatement(...);
rs = stmt.executeQuery();
... process the results ...
} catch (SQLException e) {
... process the exception ...
} finally {
DbUtils.closeQuietly(rs);
DbUtils.closeQuietly(stmt);
DbUtils.closeQuietly(conn);
}
Even further, you can avoid ResultSet and Statement closing, using methods from
QueryRunner to execute or update a database. Look into documentation, it's
pretty useful.
I hope this help. Regards,
Alfredo Ledezma Meléndez.
Gerencia de Sistemas CRM
Consultor Externo de Sistemas de Atención a Clientes
RadioMovil DIPSA, S. A. de C. V.
Ejército Nacional No. 488, Col. Anahuac, C.P. 11570
México D.F.
-Original Message-
From: Craig McClanahan [mailto:[EMAIL PROTECTED]
Sent: Thursday, July 14, 2005 5:10 PM
To: Jakarta Commons Users List; [EMAIL PROTECTED]
Subject: Re: [DBCP] Anther lame pool exhausted exception question
The key to returning connections to the connection pool is to call
close() on the *connection* itself. The most common way people get
themselves in trouble is to skip this somehow (perhaps because an
exception is thrown).
To avoid that sort of problem, I tend to use an idiom like this for
JDBC access code:
DataSource ds = ...; // Acquire a reference from JNDI or wherever
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try {
conn = ds.getConnection(); // Or whatever
stmt = conn.prepareStatement(...);
rs = stmt.executeQuery();
... process the results ...
} catch (SQLException e) {
... process the exception ...
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
... record or ignore ...
}
rs = null;
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
... record or ignore ...
}
rs = null;
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
... record or ignore ...
}
conn = null;
}
}
Courtesy of the finally logic, I'm guaranteed to always execute my
cleanup code, no matter where an exception might get thrown.
You'll note that it can be pretty tedious to do all this stuff with
raw JDBC. You might also want to look at using one of the SQL
frameworks that encapsulate this sort of stuff, but still give you the
guarantee that the connection will ultimately be returned to the pool.
Craig
On 7/14/05, Brian Cook [EMAIL PROTECTED] wrote:
I have several apps written that use org.apache.commons.dbcp. And I am
getting the org.apache.commons.dbcp.SQLNestedException: Cannot get a
connection, pool exhausted exception.
When I run netstat sure enough it shows about 60 - 100 ESTABLISHED
connections open at any given time. Looking deeper it looks like new
connections are created most but not each time the Java Bean the uses
the data base is called. So it seems pretty clear that I am failing to
close all of the connections in my app. My problem is that I can not
find where that is.
My understanding is that as long as I close every ResultSet, and each
Connection object I should have my bases covered. I have gone back
though the app repeatedly and verified that all the ResultSets,
Connections, and BasicDataSource objects are all being closed.
Due to an internal political problem I am not using JNDI for the
connections. Instead I have a class file that is called when a
connection is need. After the object is used a close() method is called
and closes the Statement, Connection, ResultSet, BasicDataSource objects.
So my questions are ..
1. Is there something else I should be doing to return the
connections to the pool?
2. Does not using JNDI with org.apache.commons.dbcp cause problems
with closing the connection pool some how?
I have been though about 6 months of the archives for this list and did
not find any hints, I went to look at the examples lnik at on the
Commons.DBCP page but the link to
http://cvs.apache.org/downviewcvs.html/jakarta-commons/dbcp/doc/ seems
to be broken. Googling has only just returned the usall advice of make
sure you are closing every connection.
I am open to any ideas or thoughts to what I am failing to due here.
Details and the code are included below.
OS
