[hibernate-dev] A framework JDBC code change suggestion...

[Max Rydahl Andersen]

Hi Joseph,

It would probably be more relevant to report this to Spring since the
code you are referring to is not within Hibernate.

p.s. first time i've seen someone having to decompile opensource classes
to fix things ;)

/max

> Hi all.
>
> In debugging a JDBC-related issue with hibernate and
> WebLogic I found a file:
>
> org.springframework.jdbc.datasource.DriverManagerDataSource.
>
> There is a part of this file that hurts JDBC concurrency
> in multithreaded applications like WebLogic, and I have a
> solution. I would like to suggest a better alternative that
> would probably be named DriverDataSource.
>    The problem is that *all* java.sql.DriverManager calls are
> class-synchronized. This include getConnection() and some very
> simple methods like DriverManager.println() which every driver
> may be calling continually at runtime (whether or not there is
> a DriverManager log stream). The constructor for SQLException
> calls this method.
>    This means that one slow call to DriverManager.getConnection()
> can temporarily block all other JDBC in the whole JVM. In some
> cases we have even seen deadlocks where one thread that holds the
> DriverManager lock calls another thread that wants to do JDBC.
>    The solution is to remove all calls to DriverManager.getConnection()
> and replace them with a simple call to Driver.connect(). In fact,
> this is what the DriverManager itself does, except that for every
> getConnection() call, the DriverManager goes through it's list of
> every registered driver in the JVM, trying each one with your URL
> and properties until it finds one that doesn't throw an exception
> and returns a connection. I decompiled and altered the
> DriverManagerDataSource to do that, for a customer to try, and I
> have attached it to this email as a suggestion for your consideration.
> HTH,
> Joe Weinstein at BEA  
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-- 
--
Max Rydahl Andersen
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Hibernate
max at hibernate.org
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