WCF Performance Counters

Article
08/07/2009

Windows Communication Foundation (WCF) includes a large set of performance counters to help you gauge your application's performance.

Enabling Performance Counters

You can enable performance counters for a WCF service through the app.config configuration file of the WCF service as follows:

<configuration>
    <system.serviceModel>
        <diagnostics performanceCounters="All" />
    </system.serviceModel>
</configuration>

The performanceCounters attribute can be set to enable a specific type of performance counters. Valid values are

All: All category counters (ServiceModelService, ServiceModelEndpoint and ServiceModelOperation) are enabled.
ServiceOnly: Only ServiceModelService category counters are enabled.
Off: ServiceModel* performance counters are disabled. This is the default value.

If you want to enable performance counters for all WCF applications, you can place the configuration settings in the Machine.config file. Please see the 'Increasing Memory Size for Performance Counters' section for more information on configuring sufficient memory for performance counters on your machine.

You can also enable performance counters in your code as follows,

using System.Configuration;
using System.ServiceModel.Configuration;
using System.ServiceModel.Diagnostics;
Configuration config = ConfigurationManager.OpenExeConfiguration(
    ConfigurationUserLevel.None);
ServiceModelSectionGroup sg = ServiceModelSectionGroup.GetSectionGroup(config);
sg.Diagnostic.PerformanceCounters = PerformanceCounterScope.All;
config.Save();

Viewing Performance Data

To view data captured by the performance counters, you can use the Performance Monitor (Perfmon.exe) that comes with Windows. You can launch this tool by going to Start, and click Run and type perfmon.exe in the dialog box.

Note:
Performance counter instances may be released before the last messages have been processed by the endpoint dispatcher. This can result in performance data not being captured for a few messages.

Increasing Memory Size for Performance Counters

WCF uses separate shared memory for its performance counter categories.

By default, separate shared memory is set to a quarter the size of global performance counter memory. The default global performance counter memory is 524,288 bytes. Therefore, the three WCF performance counter categories have a default size of approximately 128KB each. Depending upon the runtime characteristics of the WCF applications on a machine, performance counter memory may be exhausted. When this happens, WCF writes an error to the application event log. The content of the error states that a performance counter was not loaded, and the entry contains the exception "System.InvalidOperationException: Custom counters file view is out of memory." If tracing is enabled at the error level, this failure is also traced. If performance counter memory is exhausted, continuing to run your WCF applications with performance counters enabled could result in performance degradation. If you are an administrator of the machine, you should configure it to allocate enough memory to support the maximum number of performance counters that can exist at any time. For more information, see performanceCounters.

You can change the amount of performance counter memory for WCF categories in the registry. To do so, you need to add a new DWORD value named FileMappingSize to the three following locations, and set it to the desired value in bytes. Reboot your machine so that these changes are taken into effect.

HKLM\System\CurrentControlSet\Services\ServiceModelEndpoint 3.0.0.0\Performance
HKLM\System\CurrentControlSet\Services\ServiceModelOperation 3.0.0.0\Performance
HKLM\System\CurrentControlSet\Services\ServiceModelService 3.0.0.0\Performance

When a large number of objects (e.g., ServiceHost) are disposed of but waiting to be garbage-collected, the PrivateBytes performance counter will register an unusually high number. To resolve this problem, you can either add your own application-specific counters, or use the performanceCounters attribute to enable only service-level counters.

Types of Performance Counters

Performance counters are scoped to three different levels: Service, Endpoint and Operation.

You can use WMI to retrieve the name of a performance counter instance. For example,

Service counter instance name can be obtained through WMI Service instance's "CounterInstanceName" property.
Endpoint counter instance name can be obtained through WMI Endpoint instance's "CounterInstanceName" property.
Operation counter instance name can be obtained through WMI Endpoint instance's "GetOperationCounterInstanceName" method.

For more information on WMI, see Using Windows Management Instrumentation for Diagnostics.

Service performance counters

Service performance counters measure the service behavior as a whole and can be used to diagnose the performance of the whole service. They can be found under the ServiceModelService 3.0.0.0 performance object when viewing with Performance Monitor. The instances are named using the following pattern:

ServiceName@ServiceBaseAddress

A counter in a service scope is aggregated from counter in a collection of endpoints.

Performance counters for service instance creation are incremented when a new InstanceContext is created. Note that a new InstanceContext is created even when you receive a non-activating message (with an existing service), or when you connect to an instance from one session, end the session, and then reconnect from another session.

Endpoint performance counters

Endpoint performance counters enable you to look at data reflecting how an endpoint is accepting messages. They can be found under the ServiceModelEndpoint 3.0.0.0 performance object when viewing using the Performance Monitor. The instances are named using the following pattern:

(ServiceName).(ContractName)@(endpoint listener address)

The data is similar to what is collected for individual operations, but is only aggregated across the endpoint.

A counter in an endpoint scope is aggregated from counters in a collection of operations.

Note:
If two endpoints have identical contract names and addresses, they are mapped to the same counter instance.

Operation performance counters

Operation performance counters are found under the ServiceModelOperation 3.0.0.0 performance object when viewing with the Performance Monitor. Each operation has an individual instance. That is, if a given contract has 10 operations, 10 operation counter instances are associated with that contract. The object instances are named using the following pattern:

(ServiceName).(ContractName).(OperationName)@(first endpoint listener address)

This counter enables you to measure how the call is being used and how well the operation is performing.

When counters are visible at multiple scopes, data gathered from a higher scope are aggregated with data from lower scopes. For example, Calls at an endpoint represents the sum of all operation calls within the endpoint; Calls at a service represents the sum of all calls to all endpoints within the service.

Note:
If you have duplicate operation names on a contract, you only get one counter instances for both operations.

Programming the WCF Performance Counters

Several files are installed in the SDK install folder so that you can access the WCF performance counters programmatically. These files are listed as follows.

_ServiceModelEndpointPerfCounters.vrg
_ServiceModelOperationPerfCounters.vrg
_ServiceModelServicePerfCounters.vrg
_SMSvcHostPerfCounters.vrg
_TransactionBridgePerfCounters.vrg

For more information on how to access the counters programmatically, see Performance Counter Programming Architecture.

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