druid/docs/content/operations/metrics.md

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Druid Metrics

Druid generates metrics related to queries, ingestion, and coordination.

Metrics are emitted as JSON objects to a runtime log file or over HTTP (to a service such as Apache Kafka). Metric emission is disabled by default.

All Druid metrics share a common set of fields:

• timestamp - the time the metric was created
• metric - the name of the metric
• service - the service name that emitted the metric
• host - the host name that emitted the metric
• value - some numeric value associated with the metric

Metrics may have additional dimensions beyond those listed above.

Most metric values reset each emission period. By default druid emission period is 1 minute, this can be changed by setting the property druid.monitoring.emissionPeriod.

Available Metrics

Query Metrics

Broker

Metric	Description	Dimensions	Normal Value
query/time	Milliseconds taken to complete a query.	Common: dataSource, type, interval, hasFilters, duration, context, remoteAddress, id. Aggregation Queries: numMetrics, numComplexMetrics. GroupBy: numDimensions. TopN: threshold, dimension.	< 1s
query/bytes	number of bytes returned in query response.	Common: dataSource, type, interval, hasFilters, duration, context, remoteAddress, id. Aggregation Queries: numMetrics, numComplexMetrics. GroupBy: numDimensions. TopN: threshold, dimension.
query/node/time	Milliseconds taken to query individual historical/realtime nodes.	id, status, server.	< 1s
query/node/bytes	number of bytes returned from querying individual historical/realtime nodes.	id, status, server.
query/node/ttfb	Time to first byte. Milliseconds elapsed until broker starts receiving the response from individual historical/realtime nodes.	id, status, server.	< 1s
query/node/backpressure	Milliseconds that the channel to this node has spent suspended due to backpressure.	id, status, server.
query/intervalChunk/time	Only emitted if interval chunking is enabled. Milliseconds required to query an interval chunk.	id, status, chunkInterval (if interval chunking is enabled).	< 1s
query/count	number of total queries	This metric is only available if the QueryCountStatsMonitor module is included.
query/success/count	number of queries successfully processed	This metric is only available if the QueryCountStatsMonitor module is included.
query/failed/count	number of failed queries	This metric is only available if the QueryCountStatsMonitor module is included.
query/interrupted/count	number of queries interrupted due to cancellation or timeout	This metric is only available if the QueryCountStatsMonitor module is included.

Historical

Metric	Description	Dimensions	Normal Value
query/time	Milliseconds taken to complete a query.	Common: dataSource, type, interval, hasFilters, duration, context, remoteAddress, id. Aggregation Queries: numMetrics, numComplexMetrics. GroupBy: numDimensions. TopN: threshold, dimension.	< 1s
query/segment/time	Milliseconds taken to query individual segment. Includes time to page in the segment from disk.	id, status, segment.	several hundred milliseconds
query/wait/time	Milliseconds spent waiting for a segment to be scanned.	id, segment.	< several hundred milliseconds
segment/scan/pending	Number of segments in queue waiting to be scanned.		Close to 0
query/segmentAndCache/time	Milliseconds taken to query individual segment or hit the cache (if it is enabled on the historical node).	id, segment.	several hundred milliseconds
query/cpu/time	Microseconds of CPU time taken to complete a query	Common: dataSource, type, interval, hasFilters, duration, context, remoteAddress, id. Aggregation Queries: numMetrics, numComplexMetrics. GroupBy: numDimensions. TopN: threshold, dimension.	Varies
query/count	number of total queries	This metric is only available if the QueryCountStatsMonitor module is included.
query/success/count	number of queries successfully processed	This metric is only available if the QueryCountStatsMonitor module is included.
query/failed/count	number of failed queries	This metric is only available if the QueryCountStatsMonitor module is included.
query/interrupted/count	number of queries interrupted due to cancellation or timeout	This metric is only available if the QueryCountStatsMonitor module is included.

Real-time

Metric	Description	Dimensions	Normal Value
query/time	Milliseconds taken to complete a query.	Common: dataSource, type, interval, hasFilters, duration, context, remoteAddress, id. Aggregation Queries: numMetrics, numComplexMetrics. GroupBy: numDimensions. TopN: threshold, dimension.	< 1s
query/wait/time	Milliseconds spent waiting for a segment to be scanned.	id, segment.	several hundred milliseconds
segment/scan/pending	Number of segments in queue waiting to be scanned.		Close to 0
query/count	number of total queries	This metric is only available if the QueryCountStatsMonitor module is included.
query/success/count	number of queries successfully processed	This metric is only available if the QueryCountStatsMonitor module is included.
query/failed/count	number of failed queries	This metric is only available if the QueryCountStatsMonitor module is included.
query/interrupted/count	number of queries interrupted due to cancellation or timeout	This metric is only available if the QueryCountStatsMonitor module is included.

Jetty

Metric	Description	Normal Value
jetty/numOpenConnections	Number of open jetty connections.	Not much higher than number of jetty threads.

Cache

Metric	Description	Normal Value
query/cache/delta/*	Cache metrics since the last emission.
query/cache/total/*	Total cache metrics.

Metric	Description	Dimensions	Normal Value
*/numEntries	Number of cache entries.		Varies.
*/sizeBytes	Size in bytes of cache entries.		Varies.
*/hits	Number of cache hits.		Varies.
*/misses	Number of cache misses.		Varies.
*/evictions	Number of cache evictions.		Varies.
*/hitRate	Cache hit rate.		~40%
*/averageByte	Average cache entry byte size.		Varies.
*/timeouts	Number of cache timeouts.		0
*/errors	Number of cache errors.		0
*/put/ok	Number of new cache entries successfully cached.		Varies, but more than zero.
*/put/error	Number of new cache entries that could not be cached due to errors.		Varies, but more than zero.
*/put/oversized	Number of potential new cache entries that were skipped due to being too large (based on druid.{broker,historical,realtime}.cache.maxEntrySize properties).		Varies.

Memcached only metrics

Memcached client metrics are reported as per the following. These metrics come directly from the client as opposed to from the cache retrieval layer.

Metric	Description	Dimensions	Normal Value
query/cache/memcached/total	Cache metrics unique to memcached (only if druid.cache.type=memcached) as their actual values	Variable	N/A
query/cache/memcached/delta	Cache metrics unique to memcached (only if druid.cache.type=memcached) as their delta from the prior event emission	Variable	N/A

Ingestion Metrics

These metrics are only available if the RealtimeMetricsMonitor is included in the monitors list for the Realtime node. These metrics are deltas for each emission period.

Metric	Description	Dimensions	Normal Value
ingest/events/thrownAway	Number of events rejected because they are outside the windowPeriod.	dataSource, taskId, taskType.	0
ingest/events/unparseable	Number of events rejected because the events are unparseable.	dataSource, taskId, taskType.	0
ingest/events/duplicate	Number of events rejected because the events are duplicated.	dataSource, taskId, taskType.	0
ingest/events/processed	Number of events successfully processed per emission period.	dataSource, taskId, taskType.	Equal to your # of events per
emission period.
ingest/rows/output	Number of Druid rows persisted.	dataSource, taskId, taskType.	Your # of events with rollup.
ingest/persists/count	Number of times persist occurred.	dataSource, taskId, taskType.	Depends on configuration.
ingest/persists/time	Milliseconds spent doing intermediate persist.	dataSource, taskId, taskType.	Depends on configuration. Generally a few minutes at most.
ingest/persists/cpu	Cpu time in Nanoseconds spent on doing intermediate persist.	dataSource, taskId, taskType.	Depends on configuration. Generally a few minutes at most.
ingest/persists/backPressure	Milliseconds spent creating persist tasks and blocking waiting for them to finish.	dataSource, taskId, taskType.	0 or very low
ingest/persists/failed	Number of persists that failed.	dataSource, taskId, taskType.	0
ingest/handoff/failed	Number of handoffs that failed.	dataSource, taskId, taskType.	0
ingest/merge/time	Milliseconds spent merging intermediate segments	dataSource, taskId, taskType.	Depends on configuration. Generally a few minutes at most.
ingest/merge/cpu	Cpu time in Nanoseconds spent on merging intermediate segments.	dataSource, taskId, taskType.	Depends on configuration. Generally a few minutes at most.
ingest/handoff/count	Number of handoffs that happened.	dataSource, taskId, taskType.	Varies. Generally greater than 0 once every segment granular period if cluster operating normally
ingest/sink/count	Number of sinks not handoffed.	dataSource, taskId, taskType.	1~3
ingest/events/messageGap	Time gap between the data time in event and current system time.	dataSource, taskId, taskType.	Greater than 0, depends on the time carried in event
ingest/kafka/lag	Applicable for Kafka Indexing Service. Total lag between the offsets consumed by the Kafka indexing tasks and latest offsets in Kafka brokers across all partitions. Minimum emission period for this metric is a minute.	dataSource.	Greater than 0, should not be a very high number

Note: If the JVM does not support CPU time measurement for the current thread, ingest/merge/cpu and ingest/persists/cpu will be 0.

Indexing Service

Metric	Description	Dimensions	Normal Value
task/run/time	Milliseconds taken to run a task.	dataSource, taskId, taskType, taskStatus.	Varies.
task/action/log/time	Milliseconds taken to log a task action to the audit log.	dataSource, taskId, taskType	< 1000 (subsecond)
task/action/run/time	Milliseconds taken to execute a task action.	dataSource, taskId, taskType	Varies from subsecond to a few seconds, based on action type.
segment/added/bytes	Size in bytes of new segments created.	dataSource, taskId, taskType, interval.	Varies.
segment/moved/bytes	Size in bytes of segments moved/archived via the Move Task.	dataSource, taskId, taskType, interval.	Varies.
segment/nuked/bytes	Size in bytes of segments deleted via the Kill Task.	dataSource, taskId, taskType, interval.	Varies.

Coordination

These metrics are for the Druid coordinator and are reset each time the coordinator runs the coordination logic.

Metric	Description	Dimensions	Normal Value
segment/assigned/count	Number of segments assigned to be loaded in the cluster.	tier.	Varies.
segment/moved/count	Number of segments moved in the cluster.	tier.	Varies.
segment/dropped/count	Number of segments dropped due to being overshadowed.	tier.	Varies.
segment/deleted/count	Number of segments dropped due to rules.	tier.	Varies.
segment/unneeded/count	Number of segments dropped due to being marked as unused.	tier.	Varies.
segment/cost/raw	Used in cost balancing. The raw cost of hosting segments.	tier.	Varies.
segment/cost/normalization	Used in cost balancing. The normalization of hosting segments.	tier.	Varies.
segment/cost/normalized	Used in cost balancing. The normalized cost of hosting segments.	tier.	Varies.
segment/loadQueue/size	Size in bytes of segments to load.	server.	Varies.
segment/loadQueue/failed	Number of segments that failed to load.	server.	0
segment/loadQueue/count	Number of segments to load.	server.	Varies.
segment/dropQueue/count	Number of segments to drop.	server.	Varies.
segment/size	Size in bytes of available segments.	dataSource.	Varies.
segment/count	Number of available segments.	dataSource.	< max
segment/overShadowed/count	Number of overShadowed segments.		Varies.
segment/unavailable/count	Number of segments (not including replicas) left to load until segments that should be loaded in the cluster are available for queries.	datasource.	0
segment/underReplicated/count	Number of segments (including replicas) left to load until segments that should be loaded in the cluster are available for queries.	tier, datasource.	0

If emitBalancingStats is set to true in the coordinator dynamic configuration, then log entries for class org.apache.druid.server.coordinator.helper.DruidCoordinatorLogger will have extra information on balancing decisions.

General Health

Historical

Metric	Description	Dimensions	Normal Value
segment/max	Maximum byte limit available for segments.		Varies.
segment/used	Bytes used for served segments.	dataSource, tier, priority.	< max
segment/usedPercent	Percentage of space used by served segments.	dataSource, tier, priority.	< 100%
segment/count	Number of served segments.	dataSource, tier, priority.	Varies.
segment/pendingDelete	On-disk size in bytes of segments that are waiting to be cleared out	Varies.

JVM

These metrics are only available if the JVMMonitor module is included.

Metric	Description	Dimensions	Normal Value
jvm/pool/committed	Committed pool.	poolKind, poolName.	close to max pool
jvm/pool/init	Initial pool.	poolKind, poolName.	Varies.
jvm/pool/max	Max pool.	poolKind, poolName.	Varies.
jvm/pool/used	Pool used.	poolKind, poolName.	< max pool
jvm/bufferpool/count	Bufferpool count.	bufferPoolName.	Varies.
jvm/bufferpool/used	Bufferpool used.	bufferPoolName.	close to capacity
jvm/bufferpool/capacity	Bufferpool capacity.	bufferPoolName.	Varies.
jvm/mem/init	Initial memory.	memKind.	Varies.
jvm/mem/max	Max memory.	memKind.	Varies.
jvm/mem/used	Used memory.	memKind.	< max memory
jvm/mem/committed	Committed memory.	memKind.	close to max memory
jvm/gc/count	Garbage collection count.	gcName (cms/g1/parallel/etc.), gcGen (old/young)	Varies.
jvm/gc/cpu	Cpu time in Nanoseconds spent on garbage collection.	gcName, gcGen	Sum of jvm/gc/cpu should be within 10-30% of sum of jvm/cpu/total, depending on the GC algorithm used (reported by JvmCpuMonitor)

EventReceiverFirehose

The following metric is only available if the EventReceiverFirehoseMonitor module is included.

Metric	Description	Dimensions	Normal Value
ingest/events/buffered	Number of events queued in the EventReceiverFirehose's buffer	serviceName, dataSource, taskId, taskType, bufferCapacity
.	Equal
to current # of events in the buffer queue.
ingest/bytes/received	Number of bytes received by the EventReceiverFirehose.	serviceName, dataSource, taskId, taskType.	Varies.

Sys

These metrics are only available if the SysMonitor module is included.

Metric	Description	Dimensions	Normal Value
sys/swap/free	Free swap.		Varies.
sys/swap/max	Max swap.		Varies.
sys/swap/pageIn	Paged in swap.		Varies.
sys/swap/pageOut	Paged out swap.		Varies.
sys/disk/write/count	Writes to disk.	fsDevName, fsDirName, fsTypeName, fsSysTypeName, fsOptions.	Varies.
sys/disk/read/count	Reads from disk.	fsDevName, fsDirName, fsTypeName, fsSysTypeName, fsOptions.	Varies.
sys/disk/write/size	Bytes written to disk. Can we used to determine how much paging is occuring with regards to segments.	fsDevName, fsDirName, fsTypeName, fsSysTypeName, fsOptions.	Varies.
sys/disk/read/size	Bytes read from disk. Can we used to determine how much paging is occuring with regards to segments.	fsDevName, fsDirName, fsTypeName, fsSysTypeName, fsOptions.	Varies.
sys/net/write/size	Bytes written to the network.	netName, netAddress, netHwaddr	Varies.
sys/net/read/size	Bytes read from the network.	netName, netAddress, netHwaddr	Varies.
sys/fs/used	Filesystem bytes used.	fsDevName, fsDirName, fsTypeName, fsSysTypeName, fsOptions.	< max
sys/fs/max	Filesystesm bytes max.	fsDevName, fsDirName, fsTypeName, fsSysTypeName, fsOptions.	Varies.
sys/mem/used	Memory used.		< max
sys/mem/max	Memory max.		Varies.
sys/storage/used	Disk space used.	fsDirName.	Varies.
sys/cpu	CPU used.	cpuName, cpuTime.	Varies.