Marcin Kuthan created KAFKA-6925:
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Summary: Memory leak in
org.apache.kafka.streams.processor.internals.StreamThread$StreamsMetricsThreadImpl
Key: KAFKA-6925
URL: https://issues.apache.org/jira/browse/KAFKA-6925
Project: Kafka
Issue Type: Bug
Components: streams
Affects Versions: 1.0.1
Reporter: Marcin Kuthan
The retained heap of
org.apache.kafka.streams.processor.internals.StreamThread$StreamsMetricsThreadImpl
is surprisingly high for long running job. Over 100MB of heap for every stream
after a week of uptime, when for the same application a few hours after start
takes 2MB.
For the problematic instance majority of memory StreamsMetricsThreadImpl is
occupied by hash map entries in parentSensors, over 8000 elements 100+kB each.
For fresh instance there are less than 200 elements.
Below you could find retained set report generated from Eclipse Mat but I'm not
fully sure about correctness due to complex object graph in the metrics related
code.
{code:java}
Class Name | Objects | Shallow Heap
-----------------------------------------------------------------------------------------------------------
org.apache.kafka.common.metrics.KafkaMetric | 140,476 | 4,495,232
org.apache.kafka.common.MetricName | 140,476 | 4,495,232
org.apache.kafka.common.metrics.stats.SampledStat$Sample | 73,599 | 3,532,752
org.apache.kafka.common.metrics.stats.Meter | 42,104 | 1,347,328
org.apache.kafka.common.metrics.stats.Count | 42,104 | 1,347,328
org.apache.kafka.common.metrics.stats.Rate | 42,104 | 1,010,496
org.apache.kafka.common.metrics.stats.Total | 42,104 | 1,010,496
org.apache.kafka.common.metrics.stats.Max | 28,134 | 900,288
org.apache.kafka.common.metrics.stats.Avg | 28,134 | 900,288
org.apache.kafka.common.metrics.Sensor | 3,164 | 202,496
org.apache.kafka.common.metrics.Sensor[] | 3,164 | 71,088
org.apache.kafka.streams.processor.internals.StreamThread$StreamsMetricsThreadImpl|
1 | 56
-----------------------------------------------------------------------------------------------------------
{code}
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