This chapter describes the tools you can use to monitor a broker and how you can get metrics data. The chapter has the following sections:
Reference information on specific metrics is available in Chapter 18, Metrics Reference
There are three monitoring interfaces for Message QueueTM information: log files, interactive commands, and a client API that can obtain metrics. Each has its advantages and disadvantages, as follows:
Log files provide a long-term record of metrics data, but cannot easily be parsed.
Commands enable you to quickly sample information tailored to your needs, but do not enable you to look at historical information or manipulate the data programmatically.
The client API lets you extract information, process it, manipulate the data, present graphs or send alerts. However, to use it, you must write a custom application to capture and analyze the data.
Table 10–1 compares the different tools.
Table 10–1 Benefits and Limitations of Metrics Monitoring Tools
Metrics Monitoring Tool |
Benefits |
Limitations |
---|---|---|
imqcmd metrics |
Remote monitoring Convenient for spot checking Reporting interval set in command option; can be changed on the fly Easy to select specific data of interest Data presented in easy tabular format |
No single command gets all data Difficult to analyze data programmatically Doesn’t create historical record Difficult to see historical trends |
Log files |
Regular sampling Creates a historical record |
Need to configure broker properties; must shut down and restart broker to take effect Local monitoring only Data format very difficult to read or parse; no parsing tools Reporting interval cannot be changed on the fly; the same for all metrics data Does not provide flexibility in selection of data Broker metrics only; destination and connection service metrics not included Possible performance hit if interval set too short |
Client API |
Remote monitoring Easy to select specific data of interest Data can be analyzed programmatically and presented in any format |
Need to configure broker properties; must shut down and restart broker to take effect You need to write your own metrics monitoring client Reporting interval cannot be changed on the fly; the same for all metrics data |
In addition to the differences shown in the table, each tool gathers a somewhat different subset of the metrics information generated by the broker. For information on which metrics data is gathered by each monitoring tool, see Chapter 18, Metrics Reference.
The Message Queue logger takes information generated by broker code, a debugger, and a metrics generator and writes that information to a number of output channels: to standard output (the console), to a log file, and, on Solaris™ operating systems, to the syslog daemon process.
You can specify the type of information gathered by the logger as well as the type written to each of the output channels. In particular, you can specify that you want metrics information written out to a log file.
This section describes the default logging configuration for the broker and explains how to redirect log information to alternative output channels, how to change log file rollover criteria, and how to send metrics data to a log file.
A broker is automatically configured to save log output to a set of rolling log files. The log files are located in a directory identified by the instance name of the associated broker (see Appendix A, Platform-Specific Locations of Message QueueTM Data):
…/instances/instanceName/log
For a broker whose life cycle is controlled by the Application Server, the log files are located in a subdirectory of the domain directory for the domain for which the broker was started:
…/appServer_domainName_dir/imq/instances/imqbroker/log
The log files are simple text files. They are named as follows, from earliest to latest:
log.txt log_1.txt log_2.txt …log_9.txt
By default, log files are rolled over once a week; the system maintains nine backup files.
To change the directory in which the log files are kept, set the property imq.log.file.dirpath to the desired path.
To change the root name of the log files from log to something else, set the imq.log.file.filename property.
The broker supports three log levels: ERROR, WARNING , INFO. Table 10–2 explains each level.
Table 10–2 Logging Levels
Level |
Description |
---|---|
ERROR |
Messages indicating problems that could cause system failure. |
WARNING |
Alerts that should be heeded but will not cause system failure. |
INFO |
Reporting of metrics and other informational messages. |
Setting a logging level gathers messages for that level and all higher levels. The default log level is INFO, so ERROR, WARNING, and INFO messages are all logged by default.
A logged message consists of a time stamp, message code, and the message itself. The volume of information varies with the log level you have set. The following is an example of an INFO message.
[13/Sep/2000:16:13:36 PDT] [B1004]: Starting the broker service using tcp [25374,100] with min threads 50 and max threads of 500 |
To change the time stamp time zone, see information about the imq.log.timezone property, which is described in Table 14–8.
Log-related properties are described in Table 14–8.
Set the log level.
Set the output channel (file, console, or both) for one or more logging categories.
If you log output to a file, configure the rollover criteria for the file.
You complete these steps by setting logger properties. You can do this in one of two ways:
Change or add logger properties in the config.properties file for a broker before you start the broker.
Specify logger command line options in the imqbrokerd command that starts the broker. You can also use the broker option -D to change logger properties (or any broker property).
Options passed on the command line override properties specified in the broker instance configuration files. The following imqbrokerd options affect logging:
Logging interval for broker metrics, in seconds
Logging level (ERROR, WARNING, INFO, or NONE)
Silent mode (no logging to console)
Log all messages to console
The following sections describe how you can change the default configuration in order to do the following:
Change the output channel (the destination of log messages)
Change rollover criteria
By default, error and warning messages are displayed on the terminal as well as being logged to a log file. (On Solaris, error messages are also written to the system’s syslog daemon.)
You can change the output channel for log messages in the following ways:
To have all log categories (for a given level) output displayed on the screen, use the -tty option to the imqbrokerd command.
To prevent log output from being displayed on the screen, use the -silent option to the imqbrokerd command.
Use the imq.log.file.output property to specify which categories of logging information should be written to the log file. For example,
imq.log.file.output=ERROR
Use the imq.log.console.output property to specify which categories of logging information should be written to the console. For example,
imq.log.console.output=INFO
On Solaris, use the imq.log.syslog.output property to specify which categories of logging information should be written to Solaris syslog. For example,
imq.log.syslog.output=NONE
Before changing logger output channels, you must make sure that logging is set at a level that supports the information you are mapping to the output channel. For example, if you set the log level to ERROR and then set the imq.log.console.output property to WARNING, no messages will be logged because you have not enabled the logging of WARNING messages.
There are two criteria for rolling over log files: time and size. The default is to use a time criteria and roll over files every seven days.
To change the time interval, you need to change the property imq.log.file.rolloversecs. For example, the following property definition changes the time interval to ten days:
imq.log.file.rolloversecs=864000
To change the rollover criteria to depend on file size, you need to set the imq.log.file.rolloverbytes property. For example, the following definition directs the broker to rollover files after they reach a limit of 500,000 bytes
imq.log.file.rolloverbytes=500000
If you set both the time-related and the size-related rollover properties, the first limit reached will trigger the rollover. As noted before, the broker maintains up to nine rollover files.
You can set or change the log file rollover properties when a broker is running. To set these properties, use the imqcmd update bkr command.
This section describes the procedure for using broker log files to report metrics information. For general information on configuring the logger, see Configuring and Using Broker Logging.
Configure the broker’s metrics generation capability:
Confirm imq.metrics.enabled=true
Generation of metrics for logging is turned on by default.
Set the metrics generation interval to a convenient number of seconds.
imq.metrics.interval=interval
This value can be set in the config.properties file or using the -metrics interval command line option when starting up the broker.
Confirm that the logger gathers metrics information:
imq.log.level=INFO |
This is the default value. This value can be set in the config.properties file or using the -loglevel level command line option when starting up the broker.
Confirm that the logger is set to write metrics information to the log file:
imq.log.file.output=INFO |
This is the default value. It can be set in the config.properties file.
Start up the broker.
The following shows sample broker metrics output to the log file:
[21/Jul/2004:11:21:18 PDT] Connections: 0 JVM Heap: 8323072 bytes (7226576 free) Threads: 0 (14-1010) In: 0 msgs (0bytes) 0 pkts (0 bytes) Out: 0 msgs (0bytes) 0 pkts (0 bytes) Rate In: 0 msgs/sec (0 bytes/sec) 0 pkts/sec (0 bytes/sec) Rate Out: 0 msgs/sec (0 bytes/sec) 0 pkts/sec (0 bytes/sec) |
For reference information about metrics data, see Chapter 18, Metrics Reference
You can monitor physical destinations by enabling dead message logging for a broker. You can log dead messages whether or not you are using a dead message queue.
If you enable dead message logging, the broker logs the following types of events:
A physical destination exceeded its maximum size.
The broker removed a message from a physical destination, for a reason such as the following:
The destination size limit has been reached.
The message time to live expired.
The message is too large.
An error occurred when the broker attempted to process the message.
If a dead message queue is in use, logging also includes the following types of events:
The broker moved a message to the dead message queue.
The broker removed a message from the dead message queue and discarded it.
The following is an example of the log format for dead messages:
[29/Mar/2006:15:35:39 PST] [B1147]: Message 8-129.145.180.87(e7:6b:dd:5d:98:aa)- 35251-1143675279400 from destination Q:q0 has been placed on the DMQ because [B0053]: Message on destination Q:q0 Expired: expiration time 1143675279402, arrival time 1143675279401, JMSTimestamp 1143675279400 |
Dead message logging is disabled by default. To enable it, set the broker attribute imq.destination.logDeadMsgs.
A Message Queue broker can report the following types of metrics:
Java Virtual Machine (JVM) metrics. Information about the JVM heap size.
Brokerwide metrics. Information about messages stored in a broker, message flows into and out of a broker, and memory use. Messages are tracked in terms of numbers of messages and numbers of bytes.
Connection Service metrics. Information about connections and connection thread resources, and information about message flows for a particular connection service.
Destination metrics. Information about message flows into and out of a particular physical destination, information about a physical destination’s consumers, and information about memory and disk space usage.
The imqcmd command can obtain metrics information for the broker as a whole, for individual connection services, and for individual physical destinations. To obtain metrics data, you generally use the metrics subcommand of imqcmd. Metrics data is written at an interval you specify, or the number of times you specify, to the console screen.
You can also use the query subcommand to view similar data that also includes configuration information. See imqcmd query for more information.
The syntax and options of imqcmd metrics are shown in Table 10–3 and Table 10–4, respectively.
Table 10–3 imqcmd metrics Subcommand SyntaxTable 10–4 imqcmd metrics Subcommand Options
This section describes the procedure for using the metrics subcommand to report metrics information.
Start the broker for which metrics information is desired.
See Starting Brokers.
Issue the appropriate imqcmd metrics subcommand and options as shown in Table 10–3 and Table 10–4.
This section contains examples of output for the imqcmd metrics subcommand. The examples show brokerwide, connection service, and physical destination metrics.
To get the rate of message and packet flow into and out of the broker at 10 second intervals, use the metrics bkr subcommand:
imqcmd metrics bkr -m rts -int 10 -u admin
This command produces output similar to the following (see data descriptions in Table 18–2):
-------------------------------------------------------- Msgs/sec Msg Bytes/sec Pkts/sec Pkt Bytes/sec In Out In Out In Out In Out -------------------------------------------------------- 0 0 27 56 0 0 38 66 10 0 7365 56 10 10 7457 1132 0 0 27 56 0 0 38 73 0 10 27 7402 10 20 1400 8459 0 0 27 56 0 0 38 73 |
To get cumulative totals for messages and packets handled by the jms connection service, use the metrics svc subcommand:
imqcmd metrics svc -n jms -m ttl -u admin
This command produces output similar to the following (see data descriptions in Table 18–3):
------------------------------------------------- Msgs Msg Bytes Pkts Pkt Bytes In Out In Out In Out In Out ------------------------------------------------- 164 100 120704 73600 282 383 135967 102127 657 100 483552 73600 775 876 498815 149948 |
To get metrics information about a physical destination, use the metrics dst subcommand:
imqcmd metrics dst -t q -n XQueue -m ttl -u admin
This command produces output similar to the following (see data descriptions in Table 18–4):
----------------------------------------------------------------------------- Msgs Msg Bytes Msg Count Total Msg Bytes (k) Largest In Out In Out Current Peak Avg Current Peak Avg Msg (k) ----------------------------------------------------------------------------- 200 200 147200 147200 0 200 0 0 143 71 0 300 200 220800 147200 100 200 10 71 143 64 0 300 300 220800 220800 0 200 0 0 143 59 0 |
To get information about a physical destination’s consumers, use the following metrics dst subcommand:
imqcmd metrics dst -t q -n SimpleQueue -m con -u admin
This command produces output similar to the following (see data descriptions in Table 18–4):
------------------------------------------------------------------ Active Consumers Backup Consumers Msg Count Current Peak Avg Current Peak Avg Current Peak Avg ------------------------------------------------------------------ 1 1 0 0 0 0 944 1000 525 |
The syntax and options of imqcmd query are shown in Table 10–5 along with a description of the metrics data provided by the command.
Table 10–5 imqcmd query Subcommand Syntax
Subcommand Syntax |
Metrics Data Provided |
|
---|---|---|
|
Information on the current number of messages and message bytes stored in broker memory and persistent store (see Displaying Broker Information). |
|
or | ||
|
Information on the current number of allocated threads and number of connections for a specified connection service (see Displaying Connection Service Information). |
|
or | ||
|
Information on the current number of producers, active and backup consumers, and messages and message bytes stored in memory and persistent store for a specified destination (see Displaying Information about Physical Destinations). |
Because of the limited metrics data provided by imqcmd query , this tool is not represented in the tables presented in Chapter 18, Metrics Reference.
Message Queue provides a metrics monitoring capability by which the broker can write metrics data into JMS messages, which it then sends to one of a number of metrics topic destinations, depending on the type of metrics information contained in the message.
You can access this metrics information by writing a client application that subscribes to the metrics topic destinations, consumes the messages in these destinations, and processes the metrics information contained in the messages.
There are five metrics topic destinations, whose names are shown in Table 10–6, along with the type of metrics messages delivered to each destination.
Table 10–6 Metrics Topic Destinations
Topic Name | |
---|---|
mq.metrics.broker | |
mq.metrics.jvm | |
mq.metrics.destination_list | |
mq.metrics.destination.queue.monitoredDestinationName |
Destination metrics for queue of specified name |
mq.metrics.destination.topic.monitoredDestinationName |
Destination metrics for topic of specified name |
This section describes the procedure for using the message-based monitoring capability to gather metrics information. The procedure includes both client development and administration tasks.
Write a metrics monitoring client.
See the Message Queue Developer's Guide for Java Clients for instructions on programming clients that subscribe to metrics topic destinations, consume metrics messages, and extract the metrics data from these messages.
Configure the broker’s Metrics Message Producer by setting broker property values in the config.properties file:
Enable metrics message production.
Set imq.metrics.topic.enabled=true
The default value is true.
Set the interval (in seconds) at which metrics messages are generated.
Set imq.metrics.topic.interval=interval .
The default is 60 seconds.
Specify whether you want metrics messages to be persistent (that is, whether they will survive a broker failure).
Set imq.metrics.topic.persist .
The default is false.
Specify how long you want metrics messages to remain in their respective destinations before being deleted.
Set imq.metrics.topic.timetolive .
The default value is 300 seconds.
Set any access control you desire on metrics topic destinations.
See the discussion in Security and Access Considerations below.
Start up your metrics monitoring client.
When consumers subscribe to a metrics topic, the metrics topic destination will automatically be created. Once a metrics topic has been created, the broker’s metrics message producer will begin sending metrics messages to the metrics topic.
There are two reasons to restrict access to metrics topic destinations:
Metrics data might include sensitive information about a broker and its resources.
Excessive numbers of subscriptions to metrics topic destinations might increase broker overhead and negatively affect performance.
Because of these considerations, it is advisable to restrict access to metrics topic destinations.
Monitoring clients are subject to the same authentication and authorization control as any other client. Only users maintained in the Message Queue user repository are allowed to connect to the broker.
You can provide additional protections by restricting access to specific metrics topic destinations through an access control properties file, as described in User Authorization: The Access Control Properties File.
For example, the following entries in an accesscontrol.properties file will deny access to the mq.metrics.broker metrics topic to everyone except user1 and user 2.
topic.mq.metrics.broker.consume.deny.user=* topic.mq.metrics.broker.consume.allow.user=user1,user2 |
The following entries will only allow users user3 to monitor topic t1.
topic.mq.metrics.destination.topic.t1.consume.deny.user=* topic.mq.metrics.destination.topic.t1.consume.allow.user=user3 |
Depending on the sensitivity of metrics data, you can also connect your metrics monitoring client to a broker using an encrypted connection. For information on using encrypted connections, see Message Encryption.
The metrics data outputs you get using the message-based monitoring API is a function of the metrics monitoring client you write. You are limited only by the data provided by the metrics generator in the broker. For a complete list of this data, see Chapter 18, Metrics Reference.