Changing topology after starting

[Curtis Stanford]

Is it possible to add and remove consumers after disruptor has been started?

[Martin Thompson]

Curtis,

Yes this is possible. I've not done an example but this can be
achieved with the SequenceGroup.

If you get the RingBuffer/Sequencer to depend on the SequenceGroup you
can then add and remove event processors to the group rather than the
RingBuffer/Sequencer this will work. When you add them it is best to
set the EventProcessor sequence to the the current cursor value. This
method can generate some garbage and I'm considering other
implementations that could be garbage free.

Martin...

On Sep 20, 5:53 pm, Curtis Stanford <cur...@stanfordcomputing.com>
wrote:

[Curtis Stanford]

Thanks Martin.

So, I've got something like:

Disruptor disruptor = new Disruptor<AsyncMessageEvent>(

new AsyncMessageEventFactory(),

30,

Executors.newCachedThreadPool(),

ClaimStrategy.Option.MULTI_THREADED,

WaitStrategy.Option.SLEEPING);

group = new SequenceGroup();

disruptor.getRingBuffer().setGatingSequences(group); // not sure about this

disruptor.start();

Now, how do I add more consumer handlers to the group? You can only add new Sequences to the SequenceGroup.

[Martin Thompson]

Hi,

The Disruptor is all about sequences :-)

Every EventProcessor has a getSequence() method. You can use this to
get the sequence of anything you need tracked. These can be added to
the group.

Martin...

On Sep 20, 6:36 pm, Curtis Stanford <cur...@stanfordcomputing.com>
wrote:

[Martin Thompson]

I've checked in a new implementation of SequenceGroup that is lock
free for add() and remove() and no longer creates an iterator when
get() is called.

This will make the next release.

[Curtis Stanford]

Thanks a lot Martin. I look forward to any examples as well :)