The Integration Service names concurrent workflow session and workflow log files based on the way you configure concurrency:
Unique instance names.
The Integration Service appends the instance name to the log file name.
Instances of the same name.
The Integration Service appends a run ID and time stamp to the log file name.
The Integration Service writes the run ID and the workflow type to the workflow log. The workflow type describes if the workflow is a concurrent workflow.
Workflow SALES_REV started with run id , run instance name [WF_CONCURRENT_SALES1], run type [Concurrent Run with Unique Instance Name].
Each session log also includes an entry that describes the workflow run ID and instance name:
Workflow: [SALES_REV] Run Instance Name: [WF_CONCURRENT_SALES1] Run Id: 
If you cannot view all the workflow log messages when the error severity level is at warning, change the error severity level of the workflow log. Change the log level from warning to info in the advanced properties of the PowerCenter Integration Service process.