Name: gm110360 Date: 08/26/2003


FULL PRODUCT VERSION :
java version "1.4.1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1-b21)
Java HotSpot(TM) Client VM (build 1.4.1-b21, mixed mode)

FULL OPERATING SYSTEM VERSION :
Microsoft Windows 2000 [Version 5.00.2195]


A DESCRIPTION OF THE PROBLEM :
Do not close this bug as a duplicate unless you have read
further.

DriverManager.getConnection() should not be synchronized.
The javadoc says that is should not be synchronized. The
engineer who closed 4263113 contended that a lot of
jdbc-enabled applications have come to expect the
synchronized behavior. My contention is how could they? The
javadoc clearly says:
"public static Connection getConnection(String url,
                               String user, String password)
throws SQLException"

"Not public static synchronized Connection ......"

Anyone who did clearly could not understand the java
documentation.

Also the workaround to use DataSource.getConnection instead
since it is not synchronized also isn't valid and does not
take in to account that fact that DataSouce.getConnection is
most likely going to call DriverManager.getConnection since
they both return an object implementing the same interface.

for example the "thin" jdbc driver shipping with Oracle
8.1.7 has an implementation of DataSource called
OracleDataSource. It used a decompiler on it to get the
source code. Here is the source for the getConnection method



    public synchronized Connection getConnection(String
string1, String string2)

        throws SQLException

    {

        makeURL();

        trace(string1 + "URL is " + m_url);

        Connection connection = null;

        if (m_use_defConn)

        {

            if (m_od == null)

                m_od = new OracleDriver();

            connection = m_od.defaultConnection();

        }

        else

            connection = DriverManager.getConnection(m_url,
string1, string2);

        return connection;

    }

The fact that OracleDataSource.getConnection itself is
synchronized is unrelated and not significant since it is
not static and one has to create a separate OracleDataSource
instance for every database.

The problem is that OracleDataSource calls
DriverManager.getConnection(), which is a static
synchronized method. Therefore a hung jdbc connection
attempt for one Oracle database locks up all subsequent jdbc
connection attempts for the life cycle of the jvm.

Oracle cannot be faulted for implementing getConnection the
way they did since they followed the contract specified by
the javadoc that DriverManager.getConnection() is not
synchronized; another example of the expectations of the
behavior of DriverManager.getConnection.


REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER WORKAROUND :
Modify DriverManager so that getConnection is not synchronized.
(Incident Review ID: 165686)
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