# High CPU usage after GC?
**URL:** https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429
**Category:** Elasticsearch
**Created:** [March 5, 2018, 3:03am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429 "2018-03-05T03:03:13Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@uLan](https://discuss.elastic.co/u/uLan)
#### Post date: [March 5, 2018, 3:03am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/1 "2018-03-05T03:03:13Z")
I got alerted that our CPU usage is high and according to some metrics elasticsearch is consuming cpu. This was the last log of elasticsearch, but it's still working fine though
```auto
[INFO][o.e.m.j.JvmGcMonitorService] [iJXOMG0] [gc][2923498] overhead, spent [261ms] collecting in the last [1s]
```
Shortly after this, the alert triggered
Another thing is that the last time this log showed the number seems to be small
```auto
[o.e.m.j.JvmGcMonitorService] [iJXOMG0] [gc][304] overhead, spent [272ms] collecting in the last [1s]
```
How could I lower down the CPU usage?
Elasticsearch is running on docker and I have set `ES_JAVA_OPTS: "-Xmx512m -Xms512m"`
---
### Author:  [@Ben96](https://discuss.elastic.co/u/Ben96)
#### Post date: [March 5, 2018, 7:50am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/2 "2018-03-05T07:50:58Z")
Is your Elasticsearch Instance is running as Master/Client & Data in the same container ?
Because 512Mb is really not enought to run a one node ELK Stack.
To be safe in you case, put at least 2G for the container.
Edit : May you have to increase your CPU's
---
### Author:  [@uLan](https://discuss.elastic.co/u/uLan)
#### Post date: [March 5, 2018, 8:08am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/3 "2018-03-05T08:08:46Z")
Yes it is. I could increase the heap size but the issue here though is that it was consuming almost 0% cpu before this
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### Author:  [@Ben96](https://discuss.elastic.co/u/Ben96)
#### Post date: [March 5, 2018, 8:30am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/4 "2018-03-05T08:30:36Z")
Mhm, what were the last tasks elastic run ?
Looks something happen to consuming from 0% to 50% AVG.
Log's aren't tell what kind of event could be the fault ? (Execpt 2 lines)
---
### Author:  [@uLan](https://discuss.elastic.co/u/uLan)
#### Post date: [March 6, 2018, 3:44am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/5 "2018-03-06T03:44:22Z")
How could I know that?
---
### Author:  [@Ben96](https://discuss.elastic.co/u/Ben96)
#### Post date: [March 6, 2018, 9:39am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/6 "2018-03-06T09:39:20Z")
You could get more information from Elastic logs, at leasts more details
---
### Author:  [@uLan](https://discuss.elastic.co/u/uLan)
#### Post date: [March 6, 2018, 10:04am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/7 "2018-03-06T10:04:36Z")
Doesn't the logs go out into `STDOUT`? If so then the last logs of elasticsearch are the one I have posted originally. If there is a different file that elasticsearch logs into then I would appreciate it if you could help me find it.
---
### Author:  [@uLan](https://discuss.elastic.co/u/uLan)
#### Post date: [March 6, 2018, 10:08am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/8 "2018-03-06T10:08:45Z")
This is the contents of my log4j2 file
```auto
status = error
appender.console.type = Console
appender.console.name = console
appender.console.layout.type = PatternLayout
appender.console.layout.pattern = [%d{ISO8601}][%-5p][%-25c{1.}] %marker%m%n
rootLogger.level = info
rootLogger.appenderRef.console.ref = console
```
This means that the logs are output into the console right?
---
### Author:  [@uLan](https://discuss.elastic.co/u/uLan)
#### Post date: [March 9, 2018, 3:39am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/9 "2018-03-09T03:39:14Z")
Hi, I really need help on this. I could probably just restart my elasticsearch instance to solve this problem but I want to know what caused this.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [April 6, 2018, 3:39am UTC](https://discuss.elastic.co/t/high-cpu-usage-after-gc/122429/10 "2018-04-06T03:39:18Z")
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