JMX monitoring

The JMX monitoring feature exposes query metrics via the JMX API.

Table of contents

Setup

Enable collecting stats

By default, Collecting stats is enabled. You can disable collecting stats via the CrateDB configuration file or by running this statement:

cr> SET GLOBAL "stats.enabled" = FALSE;

Enable the JMX API

To monitor CrateDB using the JMX API, you must set the following system properties before you start CrateDB:

com.sun.management.jmxremote
com.sun.management.jmxremote.port=<JMX_PORT>
com.sun.management.jmxremote.ssl=false
com.sun.management.jmxremote.authenticate=false

Here, <JMX_PORT> sets the port number of your JMX server. JMX SSL and authentication are currently not supported.

More information about the JMX monitoring properties can be found in the JMX documentation.

You can set the Java system properties with the -D option:

sh$ ./bin/crate -Dcom.sun.management.jmxremote \
...             -Dcom.sun.management.jmxremote.port=7979 \
...             -Dcom.sun.management.jmxremote.ssl=false \
...             -Dcom.sun.management.jmxremote.authenticate=false

However, the recommended way to set system properties is via the CRATE_JAVA_OPTS environment variable, like so:

sh$ export CRATE_JAVA_OPTS="$CRATE_JAVA_OPTS \
      -Dcom.sun.management.jmxremote \
      -Dcom.sun.management.jmxremote.port=7979 \
      -Dcom.sun.management.jmxremote.ssl=false \
      -Dcom.sun.management.jmxremote.authenticate=false"
sh$ ./bin/crate

If you’re using the CrateDB Debian or RPM packages, you can set this environment variable via the /etc/default/crate configuration file.

Using Docker

To enable JMX monitoring when running CrateDB in a Docker container you have to set the following additional Java system properties:

-Djava.rmi.server.hostname=<RMI_HOSTNAME>
-Dcom.sun.management.jmxremote.rmi.port=<RMI_PORT>

Here, <RMI_HOSTNAME> is the IP address or hostname of the Docker host and <RMI_PORT> is the statically assigned port of the RMI server. For convenience, <RMI_PORT> can be set to the same port the JMX server listens on.

The <RMI_HOSTNAME> and <RMI_PORT> can be used by JMX clients (e.g. JConsole or VisualVM) to connect to the JMX server.

Here’s an example Docker command:

sh> docker run -d -e CRATE_JAVA_OPTS="\
      -Dcom.sun.management.jmxremote
      -Dcom.sun.management.jmxremote.port=7979 \
      -Dcom.sun.management.jmxremote.ssl=false \
      -Dcom.sun.management.jmxremote.authenticate=false \
      -Dcom.sun.management.jmxremote.rmi.port=7979 \
      -Djava.rmi.server.hostname=<RMI_HOSTNAME>" \
      -p 7979:7979 crate -Cnetwork.host=_site_

Here, again, <RMI_HOSTNAME> is the IP address or hostname of the Docker host.

JMX Beans

QueryStats MBean

The QueryStats MBean exposes the sum of durations, in milliseconds, total and failed count of all statements executed since the node was started, grouped by type, for SELECT, UPDATE, DELETE, INSERT, MANAGEMENT, DDL, COPY and UNDEFINED queries.

Metrics can be accessed using the JMX MBean object name io.crate.monitoring:type=QueryStats and the following attributes:

Statements total count since the node was started:

• SelectQueryTotalCount

• InsertQueryTotalCount

• UpdateQueryTotalCount

• DeleteQueryTotalCount

• ManagementQueryTotalCount

• DDLQueryTotalCount

• CopyQueryTotalCount

• UndefinedQueryTotalCount

Statements failed count since the node was started:

• SelectQueryFailedCount

• InsertQueryFailedCount

• UpdateQueryFailedCount

• DeleteQueryFailedCount

• ManagementQueryFailedCount

• DDLQueryFailedCount

• CopyQueryFailedCount

• UndefinedQueryFailedCount

The sum of the durations, in milliseconds, since the node was started, of all statement executions grouped by type:

• SelectQuerySumOfDurations

• InsertQuerySumOfDurations

• UpdateQuerySumOfDurations

• DeleteQuerySumOfDurations

• ManagementQuerySumOfDurations

• DDLQuerySumOfDurations

• CopyQuerySumOfDurations

• UndefinedQuerySumOfDurations

NodeStatus MBean

The NodeStatus JMX MBean exposes the status of the current node as boolean values.

NodeStatus can be accessed using the JMX MBean object name io.crate.monitoring:type=NodeStatus and the following attributes:

• Ready

  Defines if the node is able to process SQL statements.

NodeInfo MXBean

The NodeInfo JMX MXBean exposes information about the current node.

NodeInfo can be accessed using the JMX MXBean object name io.crate.monitoring:type=NodeInfo and the following attributes:

Name	Description
NodeId	Provides the unique identifier of the node in the cluster.
NodeName	Provides the human friendly name of the node.
ClusterStateVersion	Provides the version of the current applied cluster state.
ShardStats	Statistics about the number of shards located on the node.
ShardInfo	Detailed information about the shards located on the node.

ShardStats returns a CompositeData object containing statistics about the number of shards located on the node with the following attributes:

Name	Description
Total	The number of shards located on the node.
Primaries	The number of primary shards located on the node.
Replicas	The number of replica shards located on the node.
Unassigned	The number of unassigned shards in the cluster. If the node is the elected master node in the cluster, this will show the total number of unassigned shards in the cluster, otherwise 0.

ShardInfo returns an Array of CompositeData objects containing detailed information about the shards located on the node with the following attributes:

Name	Description
Id	The shard id. This shard id is managed by the system, ranging from 0 up to the number of configured shards of the table.
Table	The name of the table this shard belongs to.
PartitionIdent	The partition ident of a partitioned table. Empty for non-partitioned tables.
RoutingState	The current state of the shard in the routing table. Possible states are: UNASSIGNED INITIALIZING STARTED RELOCATING
State	The current state of the shard. Possible states are: CREATED RECOVERING POST_RECOVERY STARTED RELOCATED CLOSED INITIALIZING UNASSIGNED
Size	The estimated cumulated size in bytes of all files of this shard.

Connections MBean

The Connections MBean exposes information about any open connections to a CrateDB node.

It can be accessed using the io.crate.monitoring:type=Connections object name and has the following attributes:

Name	Description
HttpOpen	The number of currently established connections via HTTP
HttpTotal	The number of total connections established via HTTP over the life time of a node
PsqlOpen	The number of currently established connections via the PostgreSQL protocol
PsqlTotal	The number of total connections established via the PostgreSQL protocol over the life time of a node
TransportOpen	The number of currently established connections via the transport protocol

ThreadPools MXBean

The ThreadPools MXBean exposes statistical information about the used thread pools of a CrateDB node.

It can be accessed using the io.crate.monitoring:type=ThreadPools object name and has following attributes:

Name	Description
Generic	Thread pool statistics of the generic thread pool.
Search	Thread pool statistics of the search thread pool used by read statements on user generated tables.
Write	Thread pool statistics of the write thread pool used for writing and deleting data.
Management	Thread pool statistics of the management thread pool used by management tasks like stats collecting, repository information, shard allocations, etc.
Flush	Thread pool statistics of the flush thread pool used for fsyncing to disk and merging segments in the storage engine.
Refresh	Thread pool statistics of the refresh thread pool used for automatic and on-demand refreshing of tables
Snapshot	Thread pool statistics of the snapshot thread pool used for creating and restoring snapshots.
ForceMerge	Thread pool statistics of the force_merge thread pool used when running an optimize statement.
Listener	Thread pool statistics of the listener thread pool used on client nodes for asynchronous result listeners.
Get	Thread pool statistics of the get thread pool used when querying sys.nodes or sys.shards.
FetchShardStarted	Thread pool statistics of the fetch_shard_started thread pool used on shard allocation .
FetchShardStore	Thread pool statistics of the fetch_shard_store used on shard replication.

Each of them returns a CompositeData object containing detailed statistics of each thread pool with the following attributes:

Name	Description
poolSize	The current number of threads in the pool.
largestPoolSize	The largest number of threads that have ever simultaneously been in the pool.
queueSize	The current number of tasks in the queue.
active	The approximate number of threads that are actively executing tasks.
completed	The approximate total number of tasks that have completed execution.
rejected	The number of rejected executions.

CircuitBreakers MXBean

The CircuitBreaker MXBean exposes statistical information about all available circuit breakers of a CrateDB node.

It can be accessed using the io.crate.monitoring:type=CircuitBreakers object name and has following attributes:

Name	Description
Parent	Statistics of the parent circuit breaker containing summarized counters across all circuit breakers.
Query	Statistics of the query circuit breaker used to account memory usage of SQL execution including intermediate states e.g. on aggregation and resulting rows.
JobsLog	Statistics of the jobs_log circuit breaker used to account memory usage of the sys.jobs_log table.
OperationsLog	Statistics of the operations_log circuit breaker used to account memory usage of the sys.operations_log table.
FieldData	Statistics of the field_data circuit breaker used for estimating the amount of memory a field will require to be loaded into memory.
InFlightRequests	Statistics of the in_flight_requests circuit breaker used to account memory usage of all incoming requests on transport or HTTP level.
Request	Statistics of the request circuit breaker used to account memory usage of per-request data structure.

Each of them returns a CompositeData object containing detailed statistics of each circuit breaker with the following attributes:

Name	Description
name	The circuit breaker name this statistic belongs to.
used	The currently accounted used memory estimations.
limit	The configured limit when to trip.
trippedCount	The total number of occurred trips.

Exposing JMX via HTTP

The JMX metrics and a readiness endpoint can be exposed via HTTP (e.g. to be used by Prometheus) by using the Crate JMX HTTP Exporter Java agent. See the README in the Crate JMX HTTP Exporter repository for more information.