The number of parallel receive operations that the transport is issuing against the storage queue to pull messages out of it.
Versions 8.1.3 and higher of the transport (or versions 7.5.6 and higher for the 7.x version of the transport) calculate the value at start-up based on the endpoints message processing concurrency limit, using the following formula:
MaxConcurrency |
DegreeOfReceiveParallelism |
Batch Size |
|---|---|---|
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 1 | 3 |
| ... | 1 | ... |
| 10 | 1 | 10 |
| ... | 1 | ... |
| 20 | 1 | 20 |
| ... | 1 | ... |
| 32 | 1 | 32 |
| 50 | 2 | 32 / 18 |
| 100 | 4 | 32 / 32 / 32 / 4 |
| 200 | 7 | 32 / 32 / 32 / 32 / 32 / 32 / 32 / 8 |
| 1000 | 31 | 31 x 32 / 8 |
When the DegreeOfReceiveParallelism is explicitly set, the batch size is dynamically adjusted to fulfill the endpoints message processing limits, if possible, up to the allowed maximum of 32. For example, with a maximum concurrency set to 100 and a DegreeOfReceiveParallelism fixed to 3 an underfetching of 4 messages might occur. Therefore it is advised to tweak both DegreeOfReceiveParallelism to be in alignment with the BatchSize if required. In most cases, the dynamic calculation should be sufficient and no adjustment is required.
Versions 7.x to 7.5.5, and 8.x to 8.1.2, dynamically calculate the value based on the endpoints message processing concurrency limit, using the following equation:
Degree of parallelism = square root of MaxConcurrency
MaxConcurrency |
DegreeOfReceiveParallelism |
|---|---|
| 1 | 1 |
| 10 | 3 |
| 20 | 4 |
| 50 | 7 |
| 100 | 10 |
| 200 | 14 |
| 1000 | 32 [max] |
This means that DegreeOfReceiveParallelism message processing loops will receive up to the configured BatchSize number of messages in parallel. For example, using a BatchSize of 32 (the default) and parallelism set to 10 will allow the transport to receive 320 messages from the storage queue at the same time.
Warning
Changing the value of DegreeOfReceiveParallelism will influence the total number of storage operations against Azure Storage Services and can result in higher costs.
Warning
The values of BatchSize , DegreeOfParallelism, Concurrency, ServicePointManager Settings and the other parameters like MaximumWaitTimeWhenIdle must be selected carefully to get the desired speed from the transport without exceeding the boundaries of the allowed number of operations per second.