MaxConcurrentExecutables, a package level property in SSIS determines the number of control flow items that can be executed in parallel. The default value is -1. This is equivalent to number of processors (logical and physical) plus 2.
For example, in the below package running on my machine with 4 processors and MaxConcurrentExecutables = -1, you can see 6 tasks have completed execution and 6 are currently running. It’s executing 6 at a time because 4 processors + 2 = 6 threads.
This applies to all versions of SSIS. Parallelism is powerful when your goal is to complete a process as quickly as possible, specially when the tasks in a control flow are independent of each other.
If you’re thinking of increasing this setting to an infinity hoping to achieve a Nobel prize in performance tuning… slow down. If the words throughput, threading, multi-tasking scares you, you should be careful with this property. In most cases, the default setting can get the job done just fine.
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