JMX connector#
The JMX connector provides the ability to query Java Management Extensions (JMX) information from all nodes in a Trino cluster. This is very useful for monitoring or debugging. JMX provides information about the Java Virtual Machine and all of the software running inside it. Trino itself is heavily instrumented via JMX.
This connector can be configured so that chosen JMX information is periodically dumped and stored in memory for later access.
Configuration#
To configure the JMX connector, create a catalog properties file
etc/catalog/example.properties
with the following contents:
connector.name=jmx
To enable periodical dumps, define the following properties:
connector.name=jmx
jmx.dump-tables=java.lang:type=Runtime,trino.execution.scheduler:name=NodeScheduler
jmx.dump-period=10s
jmx.max-entries=86400
dump-tables
is a comma separated list of Managed Beans (MBean). It specifies
which MBeans are sampled and stored in memory every dump-period
. You can
configure the maximum number of history entries with max-entries
and it
defaults to 86400
. The time between dumps can be configured using
dump-period
and it defaults to 10s
.
Commas in MBean names must be escaped using double backslashes (\\
) in the
following manner:
connector.name=jmx
jmx.dump-tables=trino.memory:name=general\\,type=memorypool,trino.memory:name=reserved\\,type=memorypool
Double backslashes are required because a single backslash (\
) is used to
split the value across multiple lines in the following manner:
connector.name=jmx
jmx.dump-tables=trino.memory:name=general\\,type=memorypool,\
trino.memory:name=reserved\\,type=memorypool
Querying JMX#
The JMX connector provides two schemas.
The first one is current
that contains every MBean from every node in the Trino
cluster. You can see all of the available MBeans by running SHOW TABLES
:
SHOW TABLES FROM example.current;
MBean names map to non-standard table names, and must be quoted with double quotes when referencing them in a query. For example, the following query shows the JVM version of every node:
SELECT node, vmname, vmversion
FROM example.current."java.lang:type=runtime";
node | vmname | vmversion
--------------------------------------+-----------------------------------+-----------
ddc4df17-0b8e-4843-bb14-1b8af1a7451a | Java HotSpot(TM) 64-Bit Server VM | 24.60-b09
(1 row)
The following query shows the open and maximum file descriptor counts for each node:
SELECT openfiledescriptorcount, maxfiledescriptorcount
FROM example.current."java.lang:type=operatingsystem";
openfiledescriptorcount | maxfiledescriptorcount
-------------------------+------------------------
329 | 10240
(1 row)
The wildcard character *
may be used with table names in the current
schema.
This allows matching several MBean objects within a single query. The following query
returns information from the different Trino memory pools on each node:
SELECT freebytes, node, object_name
FROM example.current."trino.memory:*type=memorypool*";
freebytes | node | object_name
------------+---------+----------------------------------------------------------
214748364 | example | trino.memory:type=MemoryPool,name=reserved
1073741825 | example | trino.memory:type=MemoryPool,name=general
858993459 | example | trino.memory:type=MemoryPool,name=system
(3 rows)
The history
schema contains the list of tables configured in the connector properties file.
The tables have the same columns as those in the current schema, but with an additional
timestamp column that stores the time at which the snapshot was taken:
SELECT "timestamp", "uptime" FROM example.history."java.lang:type=runtime";
timestamp | uptime
-------------------------+--------
2016-01-28 10:18:50.000 | 11420
2016-01-28 10:19:00.000 | 21422
2016-01-28 10:19:10.000 | 31412
(3 rows)
SQL support#
The connector provides globally available and read operation statements to access JMX information on your Trino nodes.