# ElasticSearch high CPU on merge threads
**URL:** https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415
**Category:** Elasticsearch
**Created:** [April 5, 2016, 3:03pm UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415 "2016-04-05T15:03:38Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@razafinr](https://discuss.elastic.co/u/razafinr)
#### Post date: [April 5, 2016, 3:03pm UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415/1 "2016-04-05T15:03:38Z")
Hi,
I am doing a bulk indexing every 10 minutes using logstash to send data to ElasticSearch. For almost 20 days everything went OK, but today I am getting the following issue:
- ElasticSearch is using very high CPU , and when I am getting hot threads it seems that almost all of the big cpu thead are the Lucene merging threads.
- My bulk indexing is lasting 4 times longer.
I am running 2 elasticsearch nodes on SSD disk.
Does anyone knows where the problem could come from ?
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### Author:  [@warkolm](https://discuss.elastic.co/u/warkolm)
#### Post date: [April 5, 2016, 10:50pm UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415/2 "2016-04-05T22:50:42Z")
What version are you on?
Are there lots of deleted documents or segments?
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### Author:  [@razafinr](https://discuss.elastic.co/u/razafinr)
#### Post date: [April 6, 2016, 5:22am UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415/3 "2016-04-06T05:22:09Z")
I run ES version 2.2.1 and I dont delete docs at all
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### Author:  [@dadoonet](https://discuss.elastic.co/u/dadoonet)
#### Post date: [April 6, 2016, 5:39am UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415/4 "2016-04-06T05:39:12Z")
Are you updating a lot of documents?
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### Author:  [@razafinr](https://discuss.elastic.co/u/razafinr)
#### Post date: [April 6, 2016, 5:54am UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415/5 "2016-04-06T05:54:07Z")
Neither, basically I bulk index around 30000 docs in a new index every 10
minutes with no update/delete. My master node seems to be totally slower
than before. My search became slower as well. I really can t tell if it is
an ES or an hardware problem as I did a full cluster restart
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### Author:  [@warkolm](https://discuss.elastic.co/u/warkolm)
#### Post date: [April 6, 2016, 6:05am UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415/6 "2016-04-06T06:05:17Z")
Do you have Marvel installed to monitor your cluster? If not that'd be a good idea as it'll give you something to look at in terms of metrics.
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### Author:  [@razafinr](https://discuss.elastic.co/u/razafinr)
#### Post date: [April 6, 2016, 6:17am UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415/7 "2016-04-06T06:17:46Z")
I will install marvel and check this out. Thanks
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### Author:  [@razafinr](https://discuss.elastic.co/u/razafinr)
#### Post date: [April 6, 2016, 1:33pm UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415/8 "2016-04-06T13:33:42Z")
Could not install Marvel but the problem is solved. The problem was with the server itself and not ElasticSearch. Could not detect exactly where it was from but a full server restart solved it.
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 5, 2017, 11:01pm UTC](https://discuss.elastic.co/t/elasticsearch-high-cpu-on-merge-threads/46415/9 "2017-07-05T23:01:51Z")