# Strange Marvel exception

**URL:** <https://discuss.elastic.co/t/strange-marvel-exception/36112>\
**Category:** Elasticsearch\
**Tags:** elastic-stack-monitoring\
**Created:** [December 2, 2015, 2:21am UTC](https://discuss.elastic.co/t/strange-marvel-exception/36112 "2015-12-02T02:21:09Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Chris\_Neal](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/chris_neal/32/3527_2.png) [@Chris\_Neal](https://discuss.elastic.co/u/Chris_Neal)\
**Post date:** [December 2, 2015, 2:21am UTC](https://discuss.elastic.co/t/strange-marvel-exception/36112/1 "2015-12-02T02:21:09Z")

</div>

Hi all.

I have a dedicated Marvel cluster in my production environment. I noticed tonight that it was missing one of the nodes in my cluster. When I went to the missing data node (dedicated data only), I found this exception, seemingly out of the blue, repeated about 20 times:

```
[2015-12-01 22:09:11,685][ERROR][marvel.agent] [elasticsearch-bdprodes07] Background thread had an uncaught exception:
java.lang.ClassCastException: [J cannot be cast to [B
at org.apache.lucene.util.fst.BytesStore.ramBytesUsed(BytesStore.java:478)
at org.apache.lucene.util.fst.FST.ramBytesUsed(FST.java:435)
at org.apache.lucene.codecs.blocktree.FieldReader.ramBytesUsed(FieldReader.java:187)
at org.apache.lucene.codecs.blocktree.BlockTreeTermsReader.ramBytesUsed(BlockTreeTermsReader.java:309)
at org.apache.lucene.codecs.perfield.PerFieldPostingsFormat$FieldsReader.ramBytesUsed(PerFieldPostingsFormat.java:238)
at org.apache.lucene.index.SegmentCoreReaders.ramBytesUsed(SegmentCoreReaders.java:226)
at org.apache.lucene.index.SegmentReader.ramBytesUsed(SegmentReader.java:614)
at org.elasticsearch.index.engine.Engine.segmentsStats(Engine.java:309)
at org.elasticsearch.index.shard.IndexShard.segmentStats(IndexShard.java:652)
at org.elasticsearch.action.admin.indices.stats.CommonStats.<init>(CommonStats.java:175)

```

Then, every ~10 seconds, I'm now just getting this:

```
[2015-12-02 02:16:45,563][ERROR][marvel.agent] [elasticsearch-bdprodes07] Background thread had an uncaught exception:
java.lang.ClassCastException
[2015-12-02 02:16:57,357][ERROR][marvel.agent] [elasticsearch-bdprodes07] Background thread had an uncaught exception:
java.lang.ClassCastException
[2015-12-02 02:17:09,250][ERROR][marvel.agent] [elasticsearch-bdprodes07] Background thread had an uncaught exception:
java.lang.ClassCastException
[2015-12-02 02:17:21,863][ERROR][marvel.agent] [elasticsearch-bdprodes07] Background thread had an uncaught exception:
java.lang.ClassCastException
[2015-12-02 02:17:34,100][ERROR][marvel.agent] [elasticsearch-bdprodes07] Background thread had an uncaught exception:
java.lang.ClassCastException
[2015-12-02 02:17:45,238][ERROR][marvel.agent] [elasticsearch-bdprodes07] Background thread had an uncaught exception:
java.lang.ClassCastException
[2015-12-02 02:17:56,346][ERROR][marvel.agent] [elasticsearch-bdprodes07] Background thread had an uncaught exception:
java.lang.ClassCastException
[2015-12-02 02:18:07,968][ERROR][marvel.agent] [elasticsearch-bdprodes07] Background thread had an uncaught exception:
java.lang.ClassCastException

```

Not sure what happened, or what to do about it. Cycling the node is an obvious option, but I'd rather not take out a data node in production if I don't have to.

This cluster has been in prod for over a year, and is currently on ES 1.7.3, and Marvel 1.3.

Any ideas?

Thank you!  
Chris

---

<div class="post-metadata">

**Author:** ![tanguy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/tanguy/32/6030_2.png) [@tanguy](https://discuss.elastic.co/u/tanguy)\
**Post date:** [December 2, 2015, 9:08am UTC](https://discuss.elastic.co/t/strange-marvel-exception/36112/2 "2015-12-02T09:08:22Z")

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Hi,

Which JVM (version/vendor) are you running?

---

<div class="post-metadata">

**Author:** ![Chris\_Neal](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/chris_neal/32/3527_2.png) [@Chris\_Neal](https://discuss.elastic.co/u/Chris_Neal)\
**Post date:** [December 2, 2015, 2:08pm UTC](https://discuss.elastic.co/t/strange-marvel-exception/36112/3 "2015-12-02T14:08:00Z")

</div>

This one:

chris.neal@bdprodes07:[59]:~\> java -version  
openjdk version "1.8.0\_65"  
OpenJDK Runtime Environment (build 1.8.0\_65-b17)  
OpenJDK 64-Bit Server VM (build 25.65-b01, mixed mode)

Thanks!  
Chris

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [July 6, 2017, 1:46pm UTC](https://discuss.elastic.co/t/strange-marvel-exception/36112/4 "2017-07-06T13:46:24Z")

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