RE: path query optimization

[pieter-gmail]

Hi,

I have been optimizing Sqlg of late and eventually arrived at TinkerPop
code.

The gremlin in particular that I am interested is path queries.

Here is the test that I am running in jmh.

        //@Setup
        Vertex a = graph.addVertex(T.label, "A", "name", "a1");
        for (int i = 1; i < 1_000_001; i++) {
            Vertex b = graph.addVertex(T.label, "B", "name", "name_" + i);
            a.addEdge("outB", b);
            for (int j = 0; j < 1; j++) {
                Vertex c = graph.addVertex(T.label, "C", "name", "name_"
+ i + " " + j);
                b.addEdge("outC", c);
            }  
        }

And the query being benchmarked is

        GraphTraversal<Vertex, Path> traversal =
g.V(a).as("a").out().as("b").out().as("c").path();
        while (traversal.hasNext()) {
            Path path = traversal.next();
        }

Before the optimization, (as things are now)

Benchmark                                 Mode Cnt  Score Error       Units
GremlinPathBenchmark.g_path  avgt  100  1.086 ± 0.020   s/op

The optimization I did is in AbstractStep.prepareTraversalForNextStep,
to not call addLabels() for path gremlins as the labels are known by the
step and do not change again so there is not need to keep adding them.

    private final Traverser.Admin<E> prepareTraversalForNextStep(final
Traverser.Admin<E> traverser) {
        if (!this.traverserStepIdAndLabelsSetByChild) {
            traverser.setStepId(this.nextStep.getId());
            if (traverser instanceof B_LP_O_P_S_SE_SL_Traverser) {
            } else {
                traverser.addLabels(this.labels);
            }  
        }  
        return traverser;
    } 

After optimization,

Benchmark                                 Mode Cnt  Score Error       Units
GremlinPathBenchmark.g_path  avgt  100  0.680 ± 0.004   s/op

1.086 vs 0.689 seconds for the traversal.

I ran the Structured and Process test suites. 2 tests are failing with
this optimization.

InjectTest.g_VX1X_out_name_injectXdanielX_asXaX_mapXlengthX_path fails with

"java.lang.IllegalArgumentException: The step with label a does not exist"

and

SerializationTest.shouldSerializePathAsDetached fails with

"Caused by: java.lang.IllegalArgumentException: Class is not registered:
java.util.Collections$UnmodifiableSet"

Before investigating the failures is this optimization worth pursuing?

Thanks
Pieter