The ETL_JOB_THREAD_COUNT variable specifies the number of Extract, Transform and Load (ETL) jobs that can be run simultaneously.
1-100
2
If you only have a few jobs to be triggered few times a day, then 1 thread is sufficient. If you have tens of thousands of jobs, that needs to be triggered every minute, then you probably require thread counts like 50 or 100 (this depends on the nature of the work that your jobs perform, and your systems resources).