Search code examples
task-parallel-libraryproducer-consumertpl-dataflow

TPL default constructor BufferBlock: Value of DataFlowBlockOptions

If you use the default constructor to construct a TPL BufferBlock, are the DataFlowBlockOptions unbounded? In other words, what is the BoundedCapacity of the BufferBlock?

As stated in this SO answer, it's not possible to query nor change the values of the BufferBlock after construction.

Solution

  • You have two options to find this out: read the docs or create BufferBlock by yourself.

    From Introduction to TPL Dataflow:

    The majority of the dataflow blocks included in System.Threading.Tasks.Dataflow.dll support the specification of a bounded capacity.

    This is the limit on the number of items the block may be storing and have in flight at any one time. By default, this value is initialized to DataflowBlockOptions.Unbounded (-1), meaning that there is no limit.

    However, a developer may explicitly specify an upper bound. If a block is already at its capacity when an additional message is offered to it, that message will be postponed.

    Also, from MSDN:

    DataflowBlockOptions is mutable and can be configured through its properties.
    When specific configuration options are not set, the following defaults are used:

    Dataflow blocks capture the state of the options at their construction.
    Subsequent changes to the provided DataflowBlockOptions instance should not affect the behavior of a dataflow block.

    You can always view private members from debugger:

    from debugger

    You also may try to get/set them by reflection, but this is really not recommended.