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https://issues.apache.org/jira/browse/TINKERPOP-1830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16248449#comment-16248449
 ] 

ASF GitHub Bot commented on TINKERPOP-1830:
-------------------------------------------

Github user spmallette commented on a diff in the pull request:

    https://github.com/apache/tinkerpop/pull/745#discussion_r150381086
  
    --- Diff: 
tinkergraph-gremlin/src/main/java/org/apache/tinkerpop/gremlin/tinkergraph/structure/TinkerIndex.java
 ---
    @@ -48,17 +48,18 @@ public TinkerIndex(final TinkerGraph graph, final 
Class<T> indexClass) {
     
         protected void put(final String key, final Object value, final T 
element) {
             Map<Object, Set<T>> keyMap = this.index.get(key);
    -        if (keyMap == null) {
    -            keyMap = new ConcurrentHashMap<>();
    -            this.index.put(key, keyMap);
    +        if (null == keyMap) {
    +            Map<Object, Set<T>> tmpMap = new ConcurrentHashMap<>();
    +            this.index.putIfAbsent(key, tmpMap);
    +            keyMap = this.index.get(key);
             }
             Set<T> objects = keyMap.get(value);
             if (null == objects) {
    -            objects = new HashSet<>();
    -            keyMap.put(value, objects);
    +            Set<T> tmpObjects = ConcurrentHashMap.newKeySet();
    --- End diff --
    
    can you add a `final` here please?


> Race condition in Tinkergraph index creation 
> ---------------------------------------------
>
>                 Key: TINKERPOP-1830
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-1830
>             Project: TinkerPop
>          Issue Type: Bug
>          Components: tinkergraph
>    Affects Versions: 3.3.0, 3.2.6
>            Reporter: Michael Pollmeier
>            Priority: Minor
>             Fix For: 3.2.7, 3.3.1
>
>
> My colleage Fabian Yamaguchi <f...@shiftleft.io> discovered a race condition 
> in tinkergraph's index creation. He fixed it by simply replacing 
> `parallelStream` with `stream`. Quoting his analysis:
> > So, reading the code, you see that this.put is called in parallel, but that 
> > method seems to contain a race as get is called on the index, checked for 
> > null, and a subsequent write is performed. It still seems like using stream 
> > here fixes the problem we've been seeing, and the performance hit is not 
> > significant.



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