# Heap size filling up but CPU usage remains very low

**URL:** <https://discuss.elastic.co/t/heap-size-filling-up-but-cpu-usage-remains-very-low/112253>\
**Category:** Logstash\
**Created:** [December 18, 2017, 2:51pm UTC](https://discuss.elastic.co/t/heap-size-filling-up-but-cpu-usage-remains-very-low/112253 "2017-12-18T14:51:42Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![bamowens](https://avatars.discourse-cdn.com/v4/letter/b/dfb087/32.png) [@bamowens](https://discuss.elastic.co/u/bamowens)\
**Post date:** [December 18, 2017, 2:51pm UTC](https://discuss.elastic.co/t/heap-size-filling-up-but-cpu-usage-remains-very-low/112253/1 "2017-12-18T14:51:42Z")

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I have a very basic passthrough logstash instance with a single http input, one date formatting filter, and two outputs, one to s3 and one to another logstash instance.

I upgraded to 6.1 recently, but am continuing to see an issue where my CPU is far from saturated but my heap usage slowly creeps up over a few days.

How can I leverage more of the CPU resources and is it even right to think of it as a balancing act between memory usage and CPU usage?

Thank you!

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [January 15, 2018, 2:51pm UTC](https://discuss.elastic.co/t/heap-size-filling-up-but-cpu-usage-remains-very-low/112253/2 "2018-01-15T14:51:57Z")

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Closed on January 15, 2018, 2:51pm UTC

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