Ensure, that Result-ack is sent before Completion-ack. #4115

cbickel · 2018-11-15T16:18:59Z

Description

On invoking an action blocking, a ResultMessage and afterwards a CompletionMessage will be sent from the invoker to the controller. The CompletionMessage is always very small. Currently those two messages are sent asynchronously. If log-collection is very fast, they are sent to Kafka at the same point in time.
This could result into the condition, that the loadbalancer receives the completion-ack before the result ack. This will make the response to the customer slower, as the controller first needs to go against Kafka.

This PR will ensure, that the completion message will be sent after the reult message has been published successfully to Kafka.

Related issue and scope

I opened an issue to propose and discuss this change (#????)

My changes affect the following components

Types of changes

Bug fix (generally a non-breaking change which closes an issue).
Enhancement or new feature (adds new functionality).
Breaking change (a bug fix or enhancement which changes existing behavior).

Checklist:

I signed an Apache CLA.
I reviewed the style guides and followed the recommendations (Travis CI will check :).
I added tests to cover my changes.
My changes require further changes to the documentation.
I updated the documentation where necessary.

dubee · 2018-11-16T16:20:17Z

...er/src/main/scala/org/apache/openwhisk/core/loadBalancer/ShardingContainerPoolBalancer.scala

+          // should have arrived earlier and already resolved it. If it didn't arrive yet (what could happen if log
+          // collection is really fast and the result is very large), it will most likely arrive in a few milliseconds.
+          // If that message really got lost, the mechanism of DB-polling will take place.
+          if (!entry.blocking) entry.promise.trySuccess(Left(aid))


There may be a problem with the line activations.remove(aid) as well. Since the ID is removed from the activations TrieMap, the processResult method may not be able to find the ID when activations.get(aid).map is called.

You are right. That's a very good point.

markusthoemmes · 2018-11-20T09:35:39Z

core/invoker/src/main/scala/org/apache/openwhisk/core/containerpool/ContainerProxy.scala

-    if (job.msg.blocking) {
-      activation.foreach(
+    val sendResult = if (job.msg.blocking) {
+      activation.map(
        sendActiveAck(tid, _, job.msg.blocking, job.msg.rootControllerIndex, job.msg.user.namespace.uuid, false))


We shoudl reconcile any errors here into a Future.successful or use onComplete below. Otherwise you'll end up not sending the second message if the first failed. Unlikely, but just a teeny bit more defensive. I'd go for onComplete below, because that makes it more clear on the calling side, that you don't care about errors.

FWIW I like this solution a lot better than the one before.

codecov-io · 2018-11-20T10:55:37Z

Codecov Report

Merging #4115 into master will decrease coverage by 4.94%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #4115      +/-   ##
==========================================
- Coverage   86.25%   81.31%   -4.95%     
==========================================
  Files         151      151              
  Lines        7263     7269       +6     
  Branches      468      470       +2     
==========================================
- Hits         6265     5911     -354     
- Misses        998     1358     +360

Impacted Files	Coverage Δ
...pache/openwhisk/core/invoker/InvokerReactive.scala	`83.17% <ø> (+0.93%)`	⬆️
.../openwhisk/core/containerpool/ContainerProxy.scala	`93.42% <100%> (+0.17%)`	⬆️
...core/database/cosmosdb/RxObservableImplicits.scala	`0% <0%> (-100%)`	⬇️
...core/database/cosmosdb/CosmosDBArtifactStore.scala	`0% <0%> (-95.54%)`	⬇️
...sk/core/database/cosmosdb/CosmosDBViewMapper.scala	`0% <0%> (-92.6%)`	⬇️
...whisk/core/database/cosmosdb/CosmosDBSupport.scala	`0% <0%> (-83.34%)`	⬇️
...abase/cosmosdb/CosmosDBArtifactStoreProvider.scala	`0% <0%> (-62.5%)`	⬇️
...in/scala/org/apache/openwhisk/common/Counter.scala	`40% <0%> (-20%)`	⬇️
.../scala/org/apache/openwhisk/utils/Exceptions.scala	`20% <0%> (-20%)`	⬇️
...whisk/connector/kafka/KafkaProducerConnector.scala	`72.5% <0%> (-15%)`	⬇️
... and 2 more

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rabbah · 2018-11-20T18:36:40Z

core/invoker/src/main/scala/org/apache/openwhisk/core/containerpool/ContainerProxy.scala

@@ -530,8 +530,16 @@ class ContainerProxy(
    activationWithLogs
      .map(_.fold(_.activation, identity))
      .foreach { activation =>
-        // Sending the completionMessage to the controller asynchronously.
-        sendActiveAck(tid, activation, job.msg.blocking, job.msg.rootControllerIndex, job.msg.user.namespace.uuid, true)
+        // Sending the completionMessage to the controller asynchronously. But not before result message is sent.


maybe im confused by the view on github - is the active ack sent twice for blocking invokes?

you're right, one is ComplectionMessage and the other is ResultMessage

cbickel · 2018-11-22T09:36:18Z

PG3#3673 is 🔵

rabbah

@cbickel I added a commit which adds some comments (that helped me understand the changes). What do you think?

Also you'll notice I added a type alias so the active ack method is easier to find. I'd suggest we do that for some of the other function closures.

…ion messages. Adds a type alias for the active ack messages, and document the interface.

cbickel · 2018-11-23T08:01:11Z

@rabbah Thanks a lot for your proposed changes :)

Using these type aliases in more places makes totally sense to me.

Improves comments to clarify the ordering of result and completion messages. Adds a type alias for the active ack messages, and document the interface. Co-authored-by: Christian Bickel <[email protected]> Co-authored-by: Rodric Rabbah <[email protected]>

cbickel requested a review from dubee November 15, 2018 16:19

cbickel assigned dubee Nov 15, 2018

cbickel added the review Review for this PR has been requested and yet needs to be done. label Nov 15, 2018

dubee reviewed Nov 16, 2018

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cbickel force-pushed the ack branch from 180190a to be38cd4 Compare November 20, 2018 09:29

markusthoemmes reviewed Nov 20, 2018

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rabbah reviewed Nov 20, 2018

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cbickel changed the title ~~Don't react on Completion message of blocking requests.~~ Ensure, that Result-ack arrives before Completion-ack in Loadbalancer. Nov 21, 2018

cbickel changed the title ~~Ensure, that Result-ack arrives before Completion-ack in Loadbalancer.~~ Ensure, that Result-ack is sent before Completion-ack. Nov 21, 2018

cbickel force-pushed the ack branch from 600393e to bbcdd7c Compare November 21, 2018 11:56

cbickel requested a review from vvraskin November 22, 2018 09:36

cbickel assigned vvraskin Nov 22, 2018

Ensure that result-ack is sent before completion-ack.

1fd36bb

rabbah force-pushed the ack branch from bbcdd7c to 5e43072 Compare November 22, 2018 15:32

rabbah approved these changes Nov 22, 2018

View reviewed changes

rabbah force-pushed the ack branch from 5e43072 to 8a8cc3c Compare November 22, 2018 15:35

Add additional comments to clarify the ordering of result and complet…

c8b5215

…ion messages. Adds a type alias for the active ack messages, and document the interface.

rabbah force-pushed the ack branch from 8a8cc3c to c8b5215 Compare November 22, 2018 15:36

jiangpengcheng approved these changes Nov 23, 2018

View reviewed changes

rabbah merged commit b803c64 into apache:master Nov 23, 2018

cbickel deleted the ack branch November 23, 2018 22:17

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Ensure, that Result-ack is sent before Completion-ack. #4115

Ensure, that Result-ack is sent before Completion-ack. #4115

cbickel commented Nov 15, 2018 •

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cbickel commented Nov 23, 2018

Ensure, that Result-ack is sent before Completion-ack. #4115

Ensure, that Result-ack is sent before Completion-ack. #4115

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cbickel commented Nov 15, 2018 • edited Loading

Description

Related issue and scope

My changes affect the following components

Types of changes

Checklist:

dubee Nov 16, 2018

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markusthoemmes Nov 20, 2018

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codecov-io commented Nov 20, 2018 • edited Loading

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cbickel commented Nov 15, 2018 •

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