MaxDispatchCountUserThread does not work

[ec-steven]

I am using com.refinitiv.ema:ema:3.7.2.0, but have tried version 3.9.2 as well.

I am using com.refinitiv.ema.access.OmmConsumer#dispatch(long) when running with config.operationModel(OmmConsumerConfig.OperationModel.USER_DISPATCH).

The documentation says that MaxDispatchCountUserThread specifies the maximum number of messages the Enterprise Message API can dispatch in a single call to the OmmConsumer::dispatch().

This is exactly what I need to limit the time spent in a single call to dispatch. But it doesn't appear to work. The documentation claims that the default is 100, but I can see well over 1000 callbacks made in a single call to dispatch. And even if I set the parameter explicitly to 1 in a much smaller example where I subscribe to a single RIC, I can still see 15+ callbacks within one call to dispatch.

This appears to relate to #187. Was that ever addressed?

[L-Karchevska]

@ec-steven Thank you for reaching out! We will look into this issue and get back to you.

[L-Karchevska]

@ec-steven We've analysed the issue and the situation is as follows. The fix for the GitHub issue #187 which appears to be the same as your issue was not included into the release because at that time it degraded the performance of the API. We've recently been doing some improvements in ETAJ ValueAdd layer and need to re-evaluate the fix against the latest codebase. In case there is no performance degradation, we will include the fix into one of the future releases. We are sorry for any confusion.

[ec-steven]

Can you elaborate on the performance degradation? Is it simply because MaxDispatchCountUserThread will now be respected and there will be more calls to dispatch? If this is the case, perhaps the default can be changed to unlimited so it is compatible with the current code? This would give me the option to accept some degradation in exchange for limiting the time spent in dispatch.

To be clear, I'm trying to integrate OmmConsumer into in a single-threaded application. To do so, I need dispatch to be non-blocking. And I need it, like every other part of the application, to limit the amount of work it will do within one API call (so other parts of the application can do their work). Is there some other way to accomplish this without resorting to another thread?

[L-Karchevska]

@ec-steven Thank you for your input regarding the issue, we will re-evaluate the performance and hopefully include the fix in the future release. As for the way to limit the time spent in the dispatch method, unfortunately, there are no other ways to do this apart from the MaxDispatchCountUserThread parameter.