Can OnBarUpdate & OnMarketData execute simultaneously?

[grose]

Hi,

I have logic in an indicator that initializes some variables on each new bar, as in

int lastBar = -99;
if (lastBar != CurrentBar)
{
// -- do something...

I am processing bid/ask data, so I override both OnBarUpdate and OnMarketData. As I understand it, it's non-determinstic for any given incoming tick whether one or the other is called first. So my thinking is that code like the above needs to be in both. That should be fine as long as it's not possible for both to execute simultaneously on different threads. That would cause some problems and would require synchronization. Synchronization is expensive performance-wise, and I'd prefer not to do it. Also, while I don't believe it would happen here, it is possible to dead-lock when using synchronization.

I'd appreciate it if someone from NT could respond as to whether or not OnBarUpdate and OnMarketData can execute simultaneously on different threads, and if so, share any tips on synchornization in a NT indicator.

Regards,

Gordon

[NinjaTrader_ChelseaB]

Hi Gordon,

The NinjaScript methods are run in the same thread as the UI. The events are not guaranteed in an order (the events are not synchronous), however, they will not run simultaneously because they are run in the same thread.

However, OnBarUpdate is only run when there is a tick of data which triggers OnMarketUpDate any way. So if you need something updated every tick, writing it solely into OnMarketUpDate would suffice.

[grose]

Hi Gordon,

The NinjaScript methods are run in the same thread as the UI. The events are not guaranteed in an order (the events are not synchronous), however, they will not run simultaneously because they are run in the same thread.

However, OnBarUpdate is only run when there is a tick of data which triggers OnMarketUpDate any way. So if you need something updated every tick, writing it solely into OnMarketUpDate would suffice.

Hi Chelsea,

Great - thanks for your answer. Just to be clear, are you saying that while in general there's no guaranteed order of execution of methods, OnMarketData does always precede OnBarUpdate?

Also, can you tell me whether or not NinjaScript methods will run on the single thread of the UI in version 8, and, when you say single thread of the UI, is the UI a single chart (one thread per chart) or is the UI all of NinjaTrader?

Thanks much. This information is very helpful.

Regards,

Gordon

[NinjaTrader_CalH]

Grose,

This is not what Chelsea is saying.

If a tick of information comes in either OnMarketData() OR OnBarUpdate() will get called first.
There is synchronization between these two.

NinjaTrader 8 will be multi-threaded for everything. With NinjaTrader 7, the UI, including charts, indicators, strategies and so forth, all run on 1 thread.

[grose]

Thanks Cal and Chelsea,

One last question - when an incoming tick is the first tick of a new bar, is CurrentBar updated regardless of whether OnMarketData or OnBarUpdate is called, or is it only updated, or current, in the On BarUpdate method?

Regards,

Gordon

[NinjaTrader_CalH]

Grose,

That is going to be processed in the background by the application. OnBarUpdate() is just a method that gets called from the data.