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.

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/node/time Milliseconds taken to query individual historical/realtime nodes. id, status, server. < 1s
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

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

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

Cache

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

Ingestion Metrics

Metric Description Dimensions Normal Value
ingest/events/thrownAway Number of events rejected because they are outside the windowPeriod. dataSource. 0
ingest/events/unparseable Number of events rejected because the events are unparseable. dataSource. 0
ingest/events/processed Number of events successfully processed. dataSource. Equal to your # of events.
ingest/rows/output Number of Druid rows persisted. dataSource. Your # of events with rollup.
ingest/persists/count Number of times persist occurred. dataSource. Depends on configuration.
ingest/persists/time Milliseconds spent doing intermediate persist. dataSource. Depends on configuration.
ingest/persists/backPressure Number of persists pending. dataSource. 0
ingest/persists/failed Number of persists that failed. dataSource. 0
ingest/handoff/failed Number of handoffs that failed. dataSource. 0

Indexing Service

Metric Description Dimensions Normal Value
task/run/time Milliseconds taken to run task. dataSource, taskType, taskStatus. Varies.
segment/added/bytes Size in bytes of new segments created. dataSource, taskType, interval. Varies.
segment/moved/bytes Size in bytes of segments moved/archived via the Move Task. dataSource, taskType, interval. Varies.
segment/nuked/bytes Size in bytes of segments deleted via the Kill Task. dataSource, 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/added/count Number of segments added to 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.

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.

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 bufferPoolName. Bufferpool count. Varies.
jvm/bufferpool/used bufferPoolName. Bufferpool used. close to capacity
jvm/bufferpool/capacity bufferPoolName. Bufferpool capacity. 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 gcName. Garbage collection count. < 100
jvm/gc/time gcName. Garbage collection time. < 1s

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.