I am reading through some of the Hawkular APM code and have been looking at how trace fragments get created and written on the client side. One of the classes I am reviewing is FragmentBuilder.java. Its javadocs state that the sequence of events within a thread of execution should be in sequence. It made me wonder whether it is possible to trace async operations. I found https://issues.jboss.org/browse/HWKAPM-77 <https://issues.jboss.org/browse/HWKAPM-77> which apparently improves support for async execution. Gary, can you or anyone else familiar how things work, give a brief explanation of how things work async flows? Most everything in hawkular-metrics is async and reactive. That makes debugging difficult at times where you have to rely primarily on logging. I am wondering if Hawkular APM would be a good tool for these types of situations. - John

For a concrete example, we have a vertx-opentracing application: https://github.com/hawkular/hawkular-apm/blob/master/ examples/vertx-opentracing/order-manager/src/main/java/ org/hawkular/apm/examples/vertx/opentracing/ordermanager/ PlaceOrderHandler.java#L52 This shows where the top level span is started within the order manager service. This span is propagated through various handlers until it is finally finished here: https://github.com/hawkular/hawkular-apm/blob/master/ examples/vertx-opentracing/order-manager/src/main/java/ org/hawkular/apm/examples/vertx/opentracing/ordermanager/ PlaceOrderHandler.java#L126 Regards Gary ----- Original Message ----- > Hi John > > If I put things in OpenTracing terms, each unit of work we want to measure is > a Span, where work performed in the scope of one Span, is created as a child > of that Span - so building up a tree structure. So this is how units of > work, whether sync or async, get represented. > > So the issue is, how we identify the start and end of a Span, when they are > not necessarily occurring within the same thread. And secondly, when a child > activity is spawned, that is not in the same thread as its parent, how that > child Span becomes associated with its parent. > > The piece of code you reference is part of the original java agent, and it > relies on ThreadLocal as a way to track activity within threads - but to > support async behaviour, the agent also enables the trace sessions/context > to be propagated across threads, using context relevant ids. > > If explicitly instrumenting code with the OpenTracing API, async behaviour > can be monitored by simply passing around the Span objects. > > Let me know if you need further information in any particular area. > > Regards > Gary > > ----- Original Message ----- > > I am reading through some of the Hawkular APM code and have been looking at > > how trace fragments get created and written on the client side. One of the > > classes I am reviewing is FragmentBuilder.java. Its javadocs state that the > > sequence of events within a thread of execution should be in sequence. It > > made me wonder whether it is possible to trace async operations. I found > > https://issues.jboss.org/browse/HWKAPM-77 > > <https://issues.jboss.org/browse/HWKAPM-77> which apparently improves > > support for async execution. > > > > Gary, can you or anyone else familiar how things work, give a brief > > explanation of how things work async flows? Most everything in > > hawkular-metrics is async and reactive. That makes debugging difficult at > > times where you have to rely primarily on logging. I am wondering if > > Hawkular APM would be a good tool for these types of situations. > > > > - John > _______________________________________________ hawkular-dev mailing list hawkular-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/hawkular-dev