Just a question here,
I am using a Data class to retrieve the datasource
public class Data {
/**
* Gets a [EMAIL PROTECTED] DataSource} for database connection usage.
* @return The datasource for database connection.
* @throws SQLException
*/
public static DataSource getDataSource() throws SQLException {
if (ds == null) {
DATASOURCE.info("DataSource is NULL ");
MANY_CONNECTIONS.info("DataSource is NULL ");
try {
final Context initContext = new
InitialContext();
ds =
(BasicDataSource)initContext.lookup("java:/comp/env/jdbc/myDB");
initContext.close();
logDataSource(ds);
return ds;
} catch (final NamingException e) {
e.printStackTrace();
throw new RuntimeException("Java naming
exception when getting connection from tomcat pool: " + e.getMessage());
}
} else {
logDataSource(ds);
return ds;
}
}
}
Collection branches = new BranchData().loadBranches(Data.getDataSource(), 1);
Can the getDataSource method be static?
Thanks,
Sinoea
> From: [EMAIL PROTECTED]
> To: users@tomcat.apache.org
> Subject: Re: Tomcat 5.5, JNDI Connection Pooling, Active connections keep
> increasing....
> Date: Wed, 17 Sep 2008 12:25:17 +0200
>
>
> ----- Original Message -----
> From: "sinoea kaabi"
> To: "Tomcat Users List"
> Sent: Wednesday, September 17, 2008 11:31 AM
> Subject: RE: Tomcat 5.5, JNDI Connection Pooling, Active connections keep
> increasing....
>
>
>
> Thanks,
> First I will try to close resources before returning.
>
> Although I am sure that the finally blocks are reached, since I use logging
> in the last finally block and the log is
> outputted.
>
> try {
>
> } finally {
> connection.close();
> Data.logConnection(connection); // this is logged
> }
>
> But I'll give it a try anyway.
>
> Object object = null;
> try {
>
> } finally {
> close resources..
> }
> return object;
>
>
> The static methods are not thread-safe you say!
>
> So, what exactly does it mean when we say that Tomcat is thread safe for
> requests.
> Tomcat creates a new thread for each request, so somehow my static methods
> are then thread safe (incdirectly, since it is managed by Tomcat).
>
> Request A> new Thread A> using my static method for loadBranches(...)
> Request B> new Thread B> using my static method for loadBranches(...)
>
> Thread B must wait until Thread A is done.
>
> Since threads are managed by tomcat, no thread should be able to use a
> static method that is used by another thread.
>
> Or in fact, you must be right, should I declare them synchronized?
>
> public static synchronized loadBranches(...)
>
> Thanks,
> Sinoea
>
> =====================================
>
> Yes your finally blocks are working.... I checked that... the book is right
> ;)
>
>
> On threading..... No.... just make the class *non* static....
>
> Collection branches = *NEW*
> BranchData().loadBranches(Data.getDataSource(), 1);
>
> so now each thread has its own class.....
>
> I imagine thats tomcats pool is already thread safe...
>
> synchronized will work... but its a bottle neck... it will make tomcat Q...
> and there is a setting in tomcat somewhere where one can make it single
> threaded... but again it will slow it down... you only use that when a coder
> has cocked up ;)
>
> In threading the thing to watch is those global variables... so without
> seeing your actual code its difficult to spot problems...
> Thread safety is more of an art than a science...
>
> New should do it because every thread is getting its own class... so a class
> is isolated, the connection and everything else is inside it... and they
> cant mess with each other... in theory... if there are no shared globals...
>
> So I think whats happening in your static class is something like this...
>
> Thread 1 opens connection 1.... inside class
> Thread 2 open connection 2.... also inside class
>
> Close connection 2
> Close connection 2
>
> ie same connection is no closed twice and connection 1 slips out... that
> wont happen if the class in not static...
>
> .... I think ;)
>
> have fun...
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