Making ItemReader threadsafe

[senorita]

How do we make the StoredProcedureItemReader thread-safe?

[Dave Syer]

You can synchronize the read() method (e.g. by wrapping it in a delegator that does the synchronization). Remember that you will lose restartability, so best practice is to mark the step as not restartable and to be safe (and efficient) you can also set saveState=false on the reader.

[senorita]

I am running the StoredProcedureItemReader in a multithreaded fasion. I get the below error
Encountered an error executing the step
org.springframework.dao.InvalidDataAccessResourceU sageException: Unexpected cursor position change.

when I run in single threaded mode I dont have this issue....

[senorita]

I am using the spring class StoredprocedureItemReader....How do i synchronise the read method then?

[Dave Syer]

Did you try my original suggestion: "wrapping it in a delegator that does the synchronization"?

[senorita]

Im not sure how to do that...is there an example you can point to? Thanks a lot...

[Dave Syer]

How about this:

public SynchronizedItemReader<T> implements ItemReader<T> {
  private final ItemReader<T> delegate; 
  public SynchronizedItemReader(ItemReader<T> delegate) {
    this.delegate = delegate;
  }
  public synchronized T read () {
    return delegate.read();
  }
}

[senorita]

When I use the synchronisedItemReader, I get reader must be open to read exception.
org.springframework.batch.item.ReaderNotOpenExcept ion: Reader must be open before it can be read.

[senorita]

Im really stuck on a dead end..Could someone please review?

[senorita]

I implemented the open and close in my itemreader and it worked. Thanks for your help Dave..