memorylimiter

Memory Limiter exercise

It is recommended to limit the otelcol's memory usage early in the processors pipeline.

• Run the otelcol using prepared config file

  otelcol-contrib --config config.yaml

  You should see logs and metrics coming in:

  2022-05-24T14:57:42.568+0200	INFO	loggingexporter/logging_exporter.go:71	LogsExporter	{"#logs": 12}
  2022-05-24T14:57:47.267+0200	INFO	loggingexporter/logging_exporter.go:56	MetricsExporter	{"#metrics": 3}
  2022-05-24T14:57:52.267+0200	INFO	loggingexporter/logging_exporter.go:56	MetricsExporter	{"#metrics": 3}
  

• Read the Memory Limiter documentation

• Limit maximum memory usage for to the logs pipeline to 4mb

  You should see that metrics are comming in while logs are not:

  2022-05-24T14:51:23.332+0200	info	memorylimiterprocessor/memorylimiter.go:271	Memory usage after GC.	{"kind": "processor", "name": "memory_limiter/logs", "pipeline": "logs", "cur_mem_mib": 9}
  2022-05-24T14:51:24.329+0200	warn	memorylimiterprocessor/memorylimiter.go:281	Memory usage is above hard limit. Forcing a GC.	{"kind": "processor", "name": "memory_limiter/logs", "pipeline": "logs", "cur_mem_mib": 9}
  2022-05-24T14:51:24.330+0200	INFO	loggingexporter/logging_exporter.go:56	MetricsExporter	{"#metrics": 3}
  

• Change the logs pipeline memory limit to 128mb. You should see that the logs pipeline is working fine.

• Limit maximum memory usage for the metrics pipeline to 4mb. Do not change the memory limit for the logs pipeline.

  Metrics pipeline should not work at this point and you should see warning in otelcol logs. You should not see error from the logs pipeline:

  2022-05-24T14:54:53.071+0200	INFO	loggingexporter/logging_exporter.go:71	LogsExporter	{"#logs": 12}
  2022-05-24T14:54:53.770+0200	warn	memorylimiterprocessor/memorylimiter.go:281	Memory usage is above hard limit. Forcing a GC.	{"kind": "processor", "name": "memory_limiter/metrics", "pipeline": "metrics", "cur_mem_mib": 10}
  2022-05-24T14:54:53.773+0200	info	memorylimiterprocessor/memorylimiter.go:271	Memory usage after GC.	{"kind": "processor", "name": "memory_limiter/metrics", "pipeline": "metrics", "cur_mem_mib": 9}
  

• Change the metrics pipeline memory limit to 64mb. You should have both logs and metrics pipelines working OK again.

  2022-05-24T15:01:40.306+0200	INFO	loggingexporter/logging_exporter.go:71	LogsExporter	{"#logs": 12}
  2022-05-24T15:01:45.006+0200	INFO	loggingexporter/logging_exporter.go:56	MetricsExporter	{"#metrics": 3}
  2022-05-24T15:01:50.005+0200	INFO	loggingexporter/logging_exporter.go:56	MetricsExporter	{"#metrics": 3}