Metrics

    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:

    • - 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.

    Query metrics

    Historical

    MetricDescriptionDimensionsNormal Value
    query/timeMilliseconds 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/timeMilliseconds taken to query individual segment. Includes time to page in the segment from disk.id, status, segment.several hundred milliseconds
    query/wait/timeMilliseconds spent waiting for a segment to be scanned.id, segment.< several hundred milliseconds
    segment/scan/pendingNumber of segments in queue waiting to be scanned.Close to 0
    query/segmentAndCache/timeMilliseconds taken to query individual segment or hit the cache (if it is enabled on the Historical process).id, segment.several hundred milliseconds
    query/cpu/timeMicroseconds of CPU time taken to complete a queryCommon: dataSource, type, interval, hasFilters, duration, context, remoteAddress, id. Aggregation Queries: numMetrics, numComplexMetrics. GroupBy: numDimensions. TopN: threshold, dimension.Varies
    query/countnumber of total queriesThis metric is only available if the QueryCountStatsMonitor module is included.
    query/success/countnumber of queries successfully processedThis metric is only available if the QueryCountStatsMonitor module is included.
    query/failed/countnumber of failed queriesThis metric is only available if the QueryCountStatsMonitor module is included.
    query/interrupted/countnumber of queries interrupted due to cancellation or timeoutThis metric is only available if the QueryCountStatsMonitor module is included.

    Real-time

    MetricDescriptionDimensionsNormal Value
    query/timeMilliseconds 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/timeMilliseconds spent waiting for a segment to be scanned.id, segment.several hundred milliseconds
    segment/scan/pendingNumber of segments in queue waiting to be scanned.Close to 0
    query/countnumber of total queriesThis metric is only available if the QueryCountStatsMonitor module is included.
    query/success/countnumber of queries successfully processedThis metric is only available if the QueryCountStatsMonitor module is included.
    query/failed/countnumber of failed queriesThis metric is only available if the QueryCountStatsMonitor module is included.
    query/interrupted/countnumber of queries interrupted due to cancellation or timeoutThis metric is only available if the QueryCountStatsMonitor module is included.
    MetricDescriptionNormal Value
    jetty/numOpenConnectionsNumber of open jetty connections.Not much higher than number of jetty threads.

    Cache

    MetricDescriptionNormal Value
    query/cache/delta/Cache metrics since the last emission.N/A
    query/cache/total/Total cache metrics.N/A

    Memcached only metrics

    MetricDescriptionDimensionsNormal Value
    query/cache/memcached/totalCache metrics unique to memcached (only if druid.cache.type=memcached) as their actual valuesVariableN/A
    query/cache/memcached/deltaCache metrics unique to memcached (only if druid.cache.type=memcached) as their delta from the prior event emissionVariableN/A

    If SQL is enabled, the Broker will emit the following metrics for SQL.

    MetricDescriptionDimensionsNormal Value
    sqlQuery/timeMilliseconds taken to complete a SQL.id, nativeQueryIds, dataSource, remoteAddress, success.< 1s
    sqlQuery/bytesnumber of bytes returned in SQL response.id, nativeQueryIds, dataSource, remoteAddress, success.

    Ingestion Metrics (Kafka Indexing Service)

    These metrics are applicable for the Kafka Indexing Service.

    MetricDescriptionDimensionsNormal Value
    ingest/kafka/lagTotal 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
    ingest/kafka/maxLagMax 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
    ingest/kafka/avgLagAverage 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

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

    MetricDescriptionDimensionsNormal Value
    ingest/events/thrownAwayNumber of events rejected because they are outside the windowPeriod.dataSource, taskId, taskType.0
    ingest/events/unparseableNumber of events rejected because the events are unparseable.dataSource, taskId, taskType.0
    ingest/events/duplicateNumber of events rejected because the events are duplicated.dataSource, taskId, taskType.0
    ingest/events/processedNumber of events successfully processed per emission period.dataSource, taskId, taskType.Equal to your # of events per emission period.
    ingest/rows/outputNumber of Druid rows persisted.dataSource, taskId, taskType.Your # of events with rollup.
    ingest/persists/countNumber of times persist occurred.dataSource, taskId, taskType.Depends on configuration.
    ingest/persists/timeMilliseconds spent doing intermediate persist.dataSource, taskId, taskType.Depends on configuration. Generally a few minutes at most.
    ingest/persists/cpuCpu time in Nanoseconds spent on doing intermediate persist.dataSource, taskId, taskType.Depends on configuration. Generally a few minutes at most.
    ingest/persists/backPressureMilliseconds spent creating persist tasks and blocking waiting for them to finish.dataSource, taskId, taskType.0 or very low
    ingest/persists/failedNumber of persists that failed.dataSource, taskId, taskType.0
    ingest/handoff/failedNumber of handoffs that failed.dataSource, taskId, taskType.0
    ingest/merge/timeMilliseconds spent merging intermediate segmentsdataSource, taskId, taskType.Depends on configuration. Generally a few minutes at most.
    ingest/merge/cpuCpu time in Nanoseconds spent on merging intermediate segments.dataSource, taskId, taskType.Depends on configuration. Generally a few minutes at most.
    ingest/handoff/countNumber of handoffs that happened.dataSource, taskId, taskType.Varies. Generally greater than 0 once every segment granular period if cluster operating normally
    ingest/sink/countNumber of sinks not handoffed.dataSource, taskId, taskType.1~3
    ingest/events/messageGapTime gap between the data time in event and current system time.dataSource, taskId, taskType.Greater than 0, depends on the time carried in event

    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

    Coordination

    MetricDescriptionDimensionsNormal Value
    segment/assigned/countNumber of segments assigned to be loaded in the cluster.tier.Varies.
    segment/moved/countNumber of segments moved in the cluster.tier.Varies.
    segment/dropped/countNumber of segments dropped due to being overshadowed.tier.Varies.
    segment/deleted/countNumber of segments dropped due to rules.tier.Varies.
    segment/unneeded/countNumber of segments dropped due to being marked as unused.tier.Varies.
    segment/cost/rawUsed in cost balancing. The raw cost of hosting segments.tier.Varies.
    segment/cost/normalizationUsed in cost balancing. The normalization of hosting segments.tier.Varies.
    segment/cost/normalizedUsed in cost balancing. The normalized cost of hosting segments.tier.Varies.
    segment/loadQueue/sizeSize in bytes of segments to load.server.Varies.
    segment/loadQueue/failedNumber of segments that failed to load.server.0
    segment/loadQueue/countNumber of segments to load.server.Varies.
    segment/dropQueue/countNumber of segments to drop.server.Varies.
    segment/sizeTotal size of used segments in a data source. Emitted only for data sources to which at least one used segment belongs.dataSource.Varies.
    Number of used segments belonging to a data source. Emitted only for data sources to which at least one used segment belongs.dataSource.< max
    segment/overShadowed/countNumber of overshadowed segments.Varies.
    segment/unavailable/countNumber 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/countNumber of segments (including replicas) left to load until segments that should be loaded in the cluster are available for queries.tier, dataSource.0
    tier/historical/countNumber of available historical nodes in each tier.tier.Varies.
    tier/replication/factorConfigured maximum replication factor in each tier.tier.Varies.
    tier/required/capacityTotal capacity in bytes required in each tier.tier.Varies.
    tier/total/capacityTotal capacity in bytes available in each tier.tier.Varies.

    If emitBalancingStats is set to true in the Coordinator dynamic configuration, then for class org.apache.druid.server.coordinator.duty.EmitClusterStatsAndMetrics will have extra information on balancing decisions.

    MetricDescriptionDimensionsNormal Value
    segment/maxMaximum byte limit available for segments.Varies.
    segment/usedBytes used for served segments.dataSource, tier, priority.< max
    segment/usedPercentPercentage of space used by served segments.dataSource, tier, priority.< 100%
    segment/countNumber of served segments.dataSource, tier, priority.Varies.
    segment/pendingDeleteOn-disk size in bytes of segments that are waiting to be cleared outVaries.

    JVM

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

    MetricDescriptionDimensionsNormal Value
    jvm/pool/committedCommitted pool.poolKind, poolName.close to max pool
    jvm/pool/initInitial pool.poolKind, poolName.Varies.
    jvm/pool/maxMax pool.poolKind, poolName.Varies.
    jvm/pool/usedPool used.poolKind, poolName.< max pool
    jvm/bufferpool/countBufferpool count.bufferpoolName.Varies.
    jvm/bufferpool/usedBufferpool used.bufferpoolName.close to capacity
    jvm/bufferpool/capacityBufferpool capacity.bufferpoolName.Varies.
    jvm/mem/initInitial memory.memKind.Varies.
    jvm/mem/maxMax memory.memKind.Varies.
    jvm/mem/usedUsed memory.memKind.< max memory
    jvm/mem/committedCommitted memory.memKind.close to max memory
    jvm/gc/countGarbage collection count.gcName (cms/g1/parallel/etc.), gcGen (old/young)Varies.
    jvm/gc/cpuCount of CPU time in Nanoseconds spent on garbage collection. Note: jvm/gc/cpu represents the total time over multiple GC cycles; divide by jvm/gc/count to get the mean GC time per cyclegcName, gcGenSum of jvm/gc/cpu should be within 10-30% of sum of jvm/cpu/total, depending on the GC algorithm used (reported by )

    EventReceiverFirehose

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

    MetricDescriptionDimensionsNormal Value
    ingest/events/bufferedNumber of events queued in the EventReceiverFirehose’s bufferserviceName, dataSource, taskId, taskType, bufferCapacity.Equal to current # of events in the buffer queue.
    ingest/bytes/receivedNumber of bytes received by the EventReceiverFirehose.serviceName, dataSource, taskId, taskType.Varies.

    Sys

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