Tuning endpoint message processing

NServiceBus uses defaults that ensure good performance in common cases. While this is usually the preferred mode of operation there are situations where tuning might be desired.

Tuning concurrency

Limit maximum concurrency so that no more messages than the specified value are ever processed at the same time. If a maximum concurrency is not specified, the transport will choose an optimal value that is a balance between throughput and effective resource usage.

Sequential processing:

Set the concurrently limit value to 1 to process messages sequentially.

Examples where concurrency tuning might be relevant are:

• Non thread safe code that needs to run sequentially
• Databases that might deadlock when getting too many concurrent requests

Throttling

Throughput throttling options have been deprecated. To enable throttling on Version 6 and higher, a custom behavior should be used. The throttling sample demonstrates how such a behavior can be implemented.

Configuration

The default concurrency settings of an endpoint can be changed via code:

endpointConfiguration.LimitMessageProcessingConcurrencyTo(5);

TimeoutManager satellite queues

Depending on the chosen transport, additional queues (satellite queues) may be used to handle deferred messages like delayed retries or timeouts. Satellite queues use the default concurrency configuration. This concurrency setting can be configured using:

var timeoutManager = endpointConfiguration.TimeoutManager();
timeoutManager.LimitMessageProcessingConcurrencyTo(4);