Managing a JReport Server Cluster

Configuring performance weight

Balancing the server load

Monitoring clustered servers

On the JReport Administration page, you can administer the servers in a cluster, for example, you can configure the performance weight for the clustered servers, balance the server load to makes the servers work more effectively. If you have JReport Server Monitor installed, you can also use it to monitor the status of each clustered server.

Configuring performance weight

If you have chosen the Weighted Min-load (loadbalance.type=2) algorithm for load balancing when creating a cluster, you will have to configure a performance weight for each clustered server in the cluster. The higher performance weight you set to a clustered server, the higher chance it may get selected by the server that has the active scheduler during load balancing.

To configure performance weight:

Start a clustered server in the cluster and log onto its JReport Administration page.
Click Cluster on the system toolbar and select Weight from the drop-down menu. The Cluster - Weight page is displayed.
In the weight table, specify a weight value for each clustered server manually. Performance weight is a positive float number.
Click OK to save the weight values.
If you want to test each clustered server's performance weight value at current time, specify a catalog and a report that will be used for the testing in the Catalog and Report text fields and then click the Test button.

The following are two examples for how Least Weighted Current Reports algorithm works:

Example 1 - when there are free servers:

Active Servers	ServerA	ServerB	ServerC	Comments
Is local server	TRUE	FALSE	FALSE
Maximum concurrent reports	8	Unlimited	5
Number of currently running reports	6	6	5
Performance weight	10	10	10
Calculation
Weighted current reports	0.6	0.6	0.5
Is free	TRUE	TRUE	FALSE	Current < MaxConcurrent, or MaxConcurrent is unlimited
Candidate servers	YES	YES		Select from free servers
Candidate servers	YES	YES		Select servers which have the least Weighted current reports
Selected server	YES			Local server has higher priority

Example 2 - when there are no free servers:

Active Servers	ServerA	ServerB	ServerC	Comments
Is local server	TRUE	FALSE	FALSE
Maximum concurrent reports	10	10	10
Number of currently running reports	10	10	10
Performance weight	4	5	8
Calculation
Weighted current reports	2.5	2	1.25
Is free	FALSE	FALSE	FALSE	Current < MaxConcurrent, or MaxConcurrent is unlimited
Candidate servers	YES	YES	YES	Selects from all servers when all servers are full
Candidate servers			YES	Select servers which have the least Weighted current reports
Selected server			YES	Select ServerC

Balancing the server load

In a cluster environment, JReport Server provides a load balancing mechanism which enables the server to work more effectively.

Load balancing process

When the time of a scheduled task arrives, active schedulers compete and the winner gets to trigger the schedule.
The server that has the active scheduler selects a server in the cluster according to the load balancing algorithm specified which can either be a built-in one or a customized one, and then sends the task to the selected server.

Tip: You can also directly specify a server in a cluster to perform a scheduled task instead of using load balancing. To do this, first make sure that the Identify Server Preference option is enabled in the Profile > Customize Server Preferences > Advanced tab, and then use the Specify a preferred server to run the task option in the General tab of the Schedule dialog to specify a server manually.

Note: For the load balancing algorithms: the server that holds the active scheduler selects from the servers with the number of concurrently running reports less than maximum number first. However, if all servers are full, it will select from all of them.

You can also write your own load balancing algorithm based on the API included in JReport Server. For details, see Writing Customized Load Balancing Algorithm via API.

Monitoring clustered servers

If you have JReport Server Monitor installed, you can use it to monitor the status of each clustered server.

Before you can use JReport Server Monitor to monitor servers in a cluster, the following steps must be taken:

Modify the server.properties file in <monitor_install_root>\bin to configure the IP address and port information of one clustered server.
Copy rmi.auth from <server_install_root>\bin of the clustered server whose IP address and port information you modified in the last step to <monitor_install_root>\bin, or remove rmi.auth from <server_install_root>\bin of this clustered server.
Start JReport Server.
Launch MonitorServer.bat in <monitor_install_root>\bin to start JReport Server Monitor.
Access JReport Server Monitor using http://monitorhost:monitorport (default 8848), or by clicking Monitor on the JReport Administration page system toolbar.

Note: The Monitor tab will not be displayed on the JReport Administration page when the web.monitor.link.enable property in the server.properties file in <server_install_root>\bin is set to false. You can specify the monitor port by setting monitor.jmx.htmladaptor.port in server.properties.

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