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ASF GitHub Bot commented on FLINK-3315: --------------------------------------- Github user tillrohrmann commented on a diff in the pull request: https://github.com/apache/flink/pull/1641#discussion_r53808877 --- Diff: flink-streaming-java/src/main/java/org/apache/flink/streaming/api/graph/StreamGraphGenerator.java --- @@ -533,4 +563,33 @@ private StreamGraph generateInternal(List<StreamTransformation<?>> transformatio return Collections.singleton(transform.getId()); } + /** + * Determines the slot sharing group for an operation based on the slot sharing group set by + * the user and the slot sharing groups of the inputs. + * + * <p>If the user specifies a group name, this is taken as is. If nothing is specified and + * the input operations all have the same group name then this name is taken. Otherwise the + * default group is choosen. + * + * @param specifiedGroup The group specified by the user. + * @param inputIds The IDs of the input operations. + */ + private String determineSlotSharingGroup(String specifiedGroup, Collection<Integer> inputIds) { + if (specifiedGroup != null) { + return specifiedGroup; + } else { + String inputGroup = null; + for (int id: inputIds) { + String inputGroupCandidate = streamGraph.getSlotSharingGroup(id); + if (inputGroup == null) { + inputGroup = inputGroupCandidate; + continue; + } + if (!inputGroup.equals(inputGroupCandidate)) { --- End diff -- Can't we get rid of the `continue` statement by making this an `else if(...)` branch? > Fix Slot Sharing in Streaming API > --------------------------------- > > Key: FLINK-3315 > URL: https://issues.apache.org/jira/browse/FLINK-3315 > Project: Flink > Issue Type: Improvement > Components: Streaming > Affects Versions: 1.0.0 > Reporter: Aljoscha Krettek > Assignee: Aljoscha Krettek > Priority: Blocker > > Right now, the slot sharing/resource group logic is a bit "nebulous". The > slot sharing group that operators are put in depends on the order in which > operations are created. For example, in this case: > {code} > Source a = env.source() > Source b = env.source() > a.map().startNewResourceGroup().sink() > b.map().sink() > {code} > We end up with two resource groups: > - group 1: source a > - group 2: map(), sink(), source b, map(), sink() > The reason is that the slot sharing id is incremented when transforming the > {{startNewResouceGroup()}} call and all operators that are transformed > afterwards in graph traversal get that new slot sharing id. > (There is also {{isolateResources()}} which can be used to isolate an > operator.) > What I propose is to remove {{startNewResourceGroup()}} and > {{isolateResouces()}} and replace it with {{slotSharingGroup(String)}}. By > default, operations would be in slot sharing group "default". This allows > very fine grained control over what operators end up in which slot sharing > group. For example, I could have this topology: > {code} > Source a = env.source().slotSharingGroup("sources") > Source b = env.source().slotSharingGroup("sources") > a.map().slotSharingGroup("heavy a").sink().slotSharingGroup("sinks") > b.map().slotSharingGroup("heavy b").sink().slotSharingGroup("sinks") > {code} > Which would isolate the lightweight sources and sinks in a group and put > heavy operations inside their own slot groups. > This is a bit more low level than the previous API and requires more calls > than a simple {{startNewResourceGroup()}} but I think not many people would > use this feature and this design makes it very clear what operations end up > in the same group. -- This message was sent by Atlassian JIRA (v6.3.4#6332)