[
https://issues.apache.org/jira/browse/TINKERPOP-1822?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16503208#comment-16503208
]
ASF GitHub Bot commented on TINKERPOP-1822:
-------------------------------------------
Github user spmallette commented on a diff in the pull request:
https://github.com/apache/tinkerpop/pull/838#discussion_r193389532
--- Diff:
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/branch/RepeatStep.java
---
@@ -273,11 +300,40 @@ public RepeatEndStep(final Traversal.Admin traversal)
{
super(traversal);
}
+ final LinkedList<Traverser.Admin<S>> stashedStarts = new
LinkedList<>();
--- End diff --
An `ArrayList` sounds reasonable to me as far as the right `List`
implementation for how `stashedStarts` is being used. When I'd posed the
question I was more thinking about the more general increased memory
requirements for doing DFS in this fashion as we basically have to accumulate
what could be a fairly large list in memory in order to perform this operation.
I suppose that we do such things in `fold()`-ing steps but the user is
explicitly aware of their choice to do that when they use such a step. In the
case of `stashedStarts` the memory requirement for choosing DFS is somewhat
hidden as it's not clear from the Gremlin they've written that an internal list
is being built. Perhaps that's simply a side-effect of allowing this to work in
the way that it does (as you alluded to in your comment).
I'm still thinking that DFS will be something that users will invoke in
specific use cases where they will be more aware of the consequences of what it
is that they are doing. If that is the case, then this would perhaps just be
one more consequence of making that choice to consider.
I'd be curious to see some JFRs around the different modes of execution
that we now have. Perhaps some microbenchmarks are in order too. And then the
fun part....does OLAP still work without any change? :smile:
> Repeat should depth first search
> --------------------------------
>
> Key: TINKERPOP-1822
> URL: https://issues.apache.org/jira/browse/TINKERPOP-1822
> Project: TinkerPop
> Issue Type: Improvement
> Components: process
> Affects Versions: 3.3.0, 3.2.6
> Reporter: Robert Dale
> Priority: Major
>
> Perhaps optionally.
> See also:
> * https://groups.google.com/forum/#!topic/gremlin-users/gLSLxH_K-wE
> * https://github.com/apache/tinkerpop/pull/715
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
