When a Job contains several subJobs, you might want to execute some of the subJobs in parallel and then synchronize the executions of the other subJobs at the end of the parallel executions.
To do this, you can simply use tParallelize to orchestrate all of the subJobs to be executed.
The tParallelize component is designed for Data Integration Jobs. Do not use it in the context of Data Services Jobs or Routes because it is not thread safe between parallel requests and will cause huge memory and CPU consumption. Use a Route if parallel processing is a requirement.
In the example presented in the image, tParallelize launches at first the following subJobs: workflow_sales, workflow_rd and workflow_finance; after the executions are completed, it launches workflow_hr.
For further information about tParallelize, see the component documentation at https://help.talend.com.