Thread-safe connections

[2006 IR Open Dicussion]

By: Dave Cherkassky - dcherk

Thread-safe connections

2006-03-18 06:48

Posting here, since a post in 'Open Discussions' did not get a reply:

 

We are trying to run a subreport within a report. However we are getting an exception thrown from the subreport code because it is trying to use the same java.sql.Connection as was passed into the report. Apparently the subreport is running on a different thread. Our implementation of java.sql.Connection detects that it is being used by 2 threads at the same time and throws an IllegalStateException.

 

Questions:

- do we have to have threadsafe Connection objects to run subreports?

- what if the Connection is closed by the calling thread before the subreport is finished? Does the calling thread wait for all subreport threads?

- does each subreport have it's own thread and do they run in parallel?

- I assume that if Jasper Reports is using multiple threads it is doing thread pooling? How do we configure the pool?

 

Thanks,

Dave Cherkassky.

 

 

By: Sanjeev Saha - sanjeevsaha

RE: Thread-safe connections

2006-03-18 09:05

What version of Jasper Reports are you using?

 

Regards,

Sanjeev

 

 

By: Dave Cherkassky - dcherk

RE: Thread-safe connections

2006-03-18 12:11

The latest stable release (I think its 1.2.0) -- I just downloaded it 3 days ago.

 

Thanks,

Dave Cherkassky

 

 

By: Lucian Chirita - lucianc

RE: Thread-safe connections

2006-03-20 01:36

Usually subreports use the same connection as the master to run queries. However, this is not imposed in any way and one is able set any connection as connectionExpression for the subreport.

 

Therefore, if your connections cannot be used by several thread simultaneously, you can pass a separate connection to be used by the subreports.

 

To answer the rest of your questions:

- the master report would not close the connection before the subreports finish (see the next point)

- each subreport has its own thread. They never run in parallel, not even with the master. When a subreport needs to be filled, the parent thread launches a thread for the subreport and then waits for it to finish until resuming its own filling process. Subreport threads are mainly used to manage a call stack.

- no thread pooling is done, a new thread gets created for each subreport.

 

Regards,

Lucian