[TINKERPOP-1380] dedup() doesn't dedup in rare cases

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.2.1
• Fix Version/s: 3.2.4
• Component/s: process
• Assignee: Unassigned
• Reporter: Daniel Kuppitz
• Created: 20/Jul/16 09:03
• Updated: 30/Jan/17 17:20
• Resolved: 30/Jan/17 17:20

Description

I stumbled across this issue when I tried to solve a problem on the mailing list. It seems like a lot of steps need to be involved in order to make it reproducible.

gremlin> :set max-iteration 10
gremlin> 
gremlin> g = TinkerFactory.createModern().traversal().withComputer()
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], graphcomputer]
gremlin> g.V().repeat(both()).until(cyclicPath()).path().aggregate("x").cap("x").unfold().dedup()
==>[v[1], v[2], v[1]]
==>[v[1], v[2], v[1]]
==>[v[1], v[3], v[1]]
==>[v[1], v[3], v[1]]
==>[v[1], v[4], v[1]]
==>[v[1], v[4], v[1]]
==>[v[2], v[1], v[2]]
==>[v[2], v[1], v[2]]
==>[v[3], v[1], v[3]]
==>[v[3], v[1], v[3]]
...

I can't reproduce it w/o using repeat(), aggregate() or cap(). It is reproducible without path() though. And then it even gets a little worse; check this out:

gremlin> g.V().repeat(both()).until(cyclicPath()).aggregate("x").cap("x").unfold().dedup()
==>v[1]
==>v[1]
==>v[2]
==>v[2]
==>v[3]
==>v[3]
==>v[4]
==>v[4]
==>v[5]
==>v[5]
...
gremlin> g.V().repeat(both()).until(cyclicPath()).aggregate("x").cap("x").unfold().dedup().dedup()
java.lang.RuntimeException: java.lang.IllegalStateException: java.lang.IllegalArgumentException: The memory can only be set() during vertex program setup and terminate: x
Display stack trace? [yN]

The exception occurs only in OLAP mode, but also for more meaningful patterns (.dedup().dedup() really doesn't make much sense).

For a better / larger example see: https://groups.google.com/d/msg/gremlin-users/NMXExuvDjt0/ps7bJDYwAQAJ