Setting the default fusion scheme at the instance or domain level

The default fusion scheme is specified as a dynamic instance or domain property that takes effect without requiring an instance or domain restart. For Teracloud® Streams Version 7.2.0, the default fusion scheme is automatic.

You can set the default fusionScheme by running the streamtool setproperty command.

Valid values for the fusionScheme property are:

automatic

If you specify automatic as your fusion scheme, Teracloud® Streams determines the appropriate number of PEs to assign to the job.

Typically, this fusion scheme results in one PE per resource. However, Teracloud® Streams might change the number of PEs produced to avoid creating PEs that contain a very small number of operators, which can have a negative impact on performance.

manual

If you specify manual as your fusion scheme, you can then specify the number of PEs to assign to the job (by specifying a value for the fusionTargetPeCount parameter). The actual number of PEs might vary based on other job configuration constraints, the specifications of the application, and the configuration of the instance where you plan to deploy the application. For example, if you specify a large number of partition ex-location constraints, the resulting application might have more PEs than you expect.

legacy

If you specify legacy as your fusion scheme, each operator is typically fused into their own separate PE if no other placement config is specified in the application bundle file.