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[HWKMETRICS-683] Use the correct scheduler for the insertion work.
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Stefan Negrea committed Jun 29, 2017
1 parent 52a03f8 commit a68ffee
Showing 1 changed file with 2 additions and 1 deletion.
3 changes: 2 additions & 1 deletion api/metrics-api-jaxrs/src/main/java/org/hawkular/metrics/api/handler/GenericInserter.java
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Expand Up @@ -41,6 +41,7 @@
import io.vertx.ext.web.Router;
import io.vertx.ext.web.RoutingContext;
import rx.Observable;
import rx.schedulers.Schedulers;

@RestEndpoint(path = "/")
public class GenericInserter implements RestHandler {
Expand Down Expand Up @@ -83,6 +84,6 @@ public <T> void addData(RoutingContext ctx, MetricType<T> type) {
Observable<Metric<T>> metrics = Functions.metricToObservable(TenantFilter.getTenant(ctx), counters,
type);
Observable<Void> observable = metricsService.addDataPoints(type, metrics);
observable.subscribe(new ResultSetObserver(ctx));
observable.subscribeOn(Schedulers.io()).subscribe(new ResultSetObserver(ctx));
}
}

3 comments on commit a68ffee

@jsanda
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@jsanda jsanda commented on a68ffee Jun 29, 2017

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There is no need for the subscribeOn because addDataPoints is already async. If it was a blocking call, then you would want to use subscribeOn.

@stefannegrea
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@jsanda, that change doubled the throughput. I am still trying to understand why.

Do you have any insights into what could be going on there?

@jsanda
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@jsanda jsanda commented on a68ffee Jun 29, 2017

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I'm not really sure. The stuff that executes on subscription are the operators that set up the call chain. As I understand it the callbacks that get passed to operators are not executed on subscription. They get executed when the source observable has a value to emit and push downstream. All of the heavy lifting when values are pushed downstream via onNext. I will probably need to look at and run the tests myself. Can you point me to them?

Here is something else to consider. With Vert.x and the Cassandra driver we are operating in more async environment than we were with JAX-RS. In general we should not have to be scheduling work on the I/O scheduler since everything should already be async. One of the benefits of the async stack is that we should be able to do more work with fewer resources such as threads.

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