Debug information

Every response from Elasticsearch.Net and NEST contains a DebugInformation property that provides a human readable description of what happened during the request for both successful and failed requests

			var response = client.Search<Project>(s => s
    .Query(q => q
        .MatchAll()
    )
);

response.DebugInformation.Should().Contain("Valid NEST response");

		

This can be useful in tracking down numerous problems and can also be useful when filing an issue on the GitHub repository.

Request and response bytes

By default, the request and response bytes are not available within the debug information, but can be enabled globally on Connection Settings by setting DisableDirectStreaming. This disables direct streaming of

1. the serialized request type to the request stream
2. the response stream to a deserialized response type

			var connectionPool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));

var settings = new ConnectionSettings(connectionPool)
    .DisableDirectStreaming(); 1

var client = new ElasticClient(settings);

		

1. disable direct streaming for all requests

or on a per request basis

			var response = client.Search<Project>(s => s
    .RequestConfiguration(r => r
        .DisableDirectStreaming() 1
    )
    .Query(q => q
        .MatchAll()
    )
);

		

1. disable direct streaming for this request only

Configuring DisableDirectStreaming on an individual request takes precedence over any global configuration.

There is typically a performance and allocation cost associated with disabling direct streaming since both the request and response bytes must be buffered in memory, to allow them to be exposed on the response call details.

TCP statistics

It can often be useful to see the statistics for active TCP connections, particularly when trying to diagnose issues with the client. The client can collect the states of active TCP connections just before making a request, and expose these on the response and in the debug information.

Similarly to DisableDirectStreaming, TCP statistics can be collected for every request by configuring on ConnectionSettings

			var connectionPool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));

var settings = new ConnectionSettings(connectionPool)
    .EnableTcpStats(); 1

var client = new ElasticClient(settings);

		

1. collect TCP statistics for all requests

or on a per request basis

			var response = client.Search<Project>(s => s
    .RequestConfiguration(r => r
        .EnableTcpStats() 1
    )
    .Query(q => q
        .MatchAll()
    )
);

var debugInformation = response.DebugInformation;

		

1. collect TCP statistics for this request only

With EnableTcpStats set, the states of active TCP connections will now be included on the response and in the debug information.

The client includes a TcpStats class to help with retrieving more detail about active TCP connections should it be required

			var tcpStatistics = TcpStats.GetActiveTcpConnections(); 1
var ipv4Stats = TcpStats.GetTcpStatistics(NetworkInterfaceComponent.IPv4); 2
var ipv6Stats = TcpStats.GetTcpStatistics(NetworkInterfaceComponent.IPv6); 3

var response = client.Search<Project>(s => s
    .Query(q => q
        .MatchAll()
    )
);

		

1. Retrieve details about active TCP connections, including local and remote addresses and ports
2. Retrieve statistics about IPv4
3. Retrieve statistics about IPv6

Note

Collecting TCP statistics may not be accessible in all environments, for example, Azure App Services. When this is the case, TcpStats.GetActiveTcpConnections() returns null.

ThreadPool statistics

It can often be useful to see the statistics for thread pool threads, particularly when trying to diagnose issues with the client. The client can collect statistics for both worker threads and asynchronous I/O threads, and expose these on the response and in debug information.

Similar to collecting TCP statistics, ThreadPool statistics can be collected for all requests by configuring EnableThreadPoolStats on ConnectionSettings

			var connectionPool = new SingleNodeConnectionPool(new Uri("http://localhost:9200"));

var settings = new ConnectionSettings(connectionPool)
     .EnableThreadPoolStats(); 1

var client = new ElasticClient(settings);

		

1. collect thread pool statistics for all requests

or on a per request basis

			var response = client.Search<Project>(s => s
     .RequestConfiguration(r => r
             .EnableThreadPoolStats() 1
     )
     .Query(q => q
         .MatchAll()
     )
 );

var debugInformation = response.DebugInformation; 2

		

1. collect thread pool statistics for this request only
2. contains thread pool statistics

With EnableThreadPoolStats set, the statistics of thread pool threads will now be included on the response and in the debug information.