Cole Greer created TINKERPOP-3283:
-------------------------------------
Summary: loops() quietly overflows
Key: TINKERPOP-3283
URL: https://issues.apache.org/jira/browse/TINKERPOP-3283
Project: TinkerPop
Issue Type: Bug
Components: process
Affects Versions: 3.8.1, 3.7.6
Reporter: Cole Greer
The `loops()` step is ultimately backed by a `LabelledCounter`, which tracks
the loop count as a `short`
(https://github.com/apache/tinkerpop/blob/519a7be1576c6ccc7f028382c108f02933b1140b/gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/traverser/util/LabelledCounter.java#L30).
There is no overflow protection on this count, which can lead to some
undesirable behaviours around the boundary of 32767 (short max):
{code:java}
gremlin> g.inject(0).repeat(loops()).emit().times(32767).count()
==>32767
gremlin> g.inject(0).repeat(loops()).emit().times(32768).count()
//hung, as the loop counter overflows before reaching 32768
gremlin> g.inject(0).repeat(addV('TestNode').
property(id, constant('TID-').concat(loops().asString())).
property('rid', loops()).
property('series','M').
property('uuid', 'ab0ae056-5d59-48df-a582-92c7c1bb9fcc')).
times(80000).iterate()
Vertex with id already exists: TID-0
Type ':help' or ':h' for help.
Display stack trace? [yN]n
gremlin> g.V()
==>v[TID--25318] // writes vertices with negative value ids after loops()
overflows
==>v[TID--25319]
==>v[TID--15991]
==>v[TID--15992]
==>v[TID--15990]
==>v[TID--25310]
{code}
The silent overflow leads to really unintuitive results and should be
considered a bug. This could be solved by adding some smart overflow detection
(either resulting in a clear exception or expansion to a new long-counting
traverser), or we could simply globally expand the counter to be a long, and
suffer the impact from the increased memory consumption. These options should
each be evaluated before implementing any fix.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
