The System.Diagnostics namespace provides classes that allow you to interact with system processes, event logs, and performance counters.

• The EventLog component provides functionality to write to event logs, read event log entries, and create and delete event logs and event sources on the network. The EntryWrittenEventHandler provides a way to interact with event logs asynchronously. Supporting classes provide access to more detailed control, including: permission restrictions, the ability to specify event log types (which controls the type of default data that is written with an event log entry), and iterate through collections of event log entries. For more information about these tasks, see the EventLogPermission, EventLogEntryType, and EventLogEntryCollection classes.

• The Process class provides functionality to monitor system processes across the network, and to start and stop local system processes. In addition to retrieving lists of running processes (by specifying either the computer, the process name, or the process id) or viewing information about the process that currently has access to the processor, you can get detailed knowledge of process threads and modules both through the Process class itself, and by interacting with the ProcessThread and ProcessModule classes. The ProcessStartInfo class enables you to specify a variety of elements with which to start a new process, such as input, output, and error streams, working directories, and command line verbs and arguments. These give you fine control over the behavior of your processes. Other related classes let you specify window styles, process and thread priorities, and interact with collections of threads and modules.

• The PerformanceCounter class enables you to monitor system performance, while the PerformanceCounterCategory class provides a way to create new custom counters and categories. You can write to local custom counters and read from both local and remote counters (system as well as custom). You can sample counters using the PerformanceCounter class, and calculate results from successive performance counter samples using the CounterSample class. The CounterCreationData class enables you to create multiple counters in a category and specify their types. Other classes associated with the performance counter component provide access to collections of counters, counter permission, and counter types.

The System.Diagnostics namespace also provides classes that allow you to debug your application and to trace the execution of your code. For more information, see the Trace and Debug classes.

Classes

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	Class	Description
	BooleanSwitch	Provides a simple on/off switch that controls debugging and tracing output.
	ConditionalAttribute	Indicates to compilers that a method is callable if a specified preprocessing identifier is applied to the method.
	ConsoleTraceListener	Directs tracing or debugging output to either the standard output or the standard error stream.
	CorrelationManager	Correlates traces that are part of a logical transaction.
	CounterCreationData	Defines the counter type, name, and Help string for a custom counter.
	CounterCreationDataCollection	Provides a strongly typed collection of CounterCreationData objects.
	CounterSampleCalculator	Provides a set of utility functions for interpreting performance counter data.
	DataReceivedEventArgs	Provides data for the OutputDataReceived and ErrorDataReceived events.
	Debug	Provides a set of methods and properties that help debug your code. This class cannot be inherited.
	DebuggableAttribute	Modifies code generation for runtime just-in-time (JIT) debugging. This class cannot be inherited.
	Debugger	Enables communication with a debugger. This class cannot be inherited.
	DebuggerBrowsableAttribute	Determines if and how a member is displayed in the debugger variable windows. This class cannot be inherited.
	DebuggerDisplayAttribute	Determines how a class or field is displayed in the debugger variable windows.
	DebuggerHiddenAttribute	Specifies the DebuggerHiddenAttribute. This class cannot be inherited.
	DebuggerNonUserCodeAttribute	Identifies a type or member that is not part of the user code for an application.
	DebuggerStepperBoundaryAttribute	Indicates the code following the attribute is to be executed in run, not step, mode.
	DebuggerStepThroughAttribute	Specifies the DebuggerStepThroughAttribute. This class cannot be inherited.
	DebuggerTypeProxyAttribute	Specifies the display proxy for a type.
	DebuggerVisualizerAttribute	Specifies that the type has a visualizer. This class cannot be inherited.
	DefaultTraceListener	Provides the default output methods and behavior for tracing.
	DelimitedListTraceListener	Directs tracing or debugging output to a text writer, such as a stream writer, or to a stream, such as a file stream.
	DiagnosticsConfigurationHandler	Handles the diagnostics section of configuration files.
	EntryWrittenEventArgs	Provides data for the EntryWritten event.
	EventInstance	Represents language-neutral information for an event log entry.
	EventLog	Provides interaction with Windows event logs.
	EventLogEntry	Encapsulates a single record in the event log. This class cannot be inherited.
	EventLogEntryCollection	Defines size and enumerators for a collection of EventLogEntry instances.
	EventLogInstaller	Allows you to install and configure an event log that your application reads from or writes to when running.
	EventLogPermission	Allows control of code access permissions for event logging.
	EventLogPermissionAttribute	Allows declaritive permission checks for event logging.
	EventLogPermissionEntry	Defines the smallest unit of a code access security permission that is set for an EventLog.
	EventLogPermissionEntryCollection	Contains a strongly typed collection of EventLogPermissionEntry objects.
	EventLogTraceListener	Provides a simple listener that directs tracing or debugging output to an EventLog.
	EventSourceCreationData	Represents the configuration settings used to create an event log source on the local computer or a remote computer.
	EventTypeFilter	Indicates whether a listener should trace based on the event type.
	FileVersionInfo	Provides version information for a physical file on disk.
	InstanceData	Holds instance data associated with a performance counter sample.
	InstanceDataCollection	Provides a strongly typed collection of InstanceData objects.
	InstanceDataCollectionCollection	Provides a strongly typed collection of InstanceDataCollection objects.
	MonitoringDescriptionAttribute	Specifies a description for a property or event.
	PerformanceCounter	Represents a Windows NT performance counter component.
	PerformanceCounterCategory	Represents a performance object, which defines a category of performance counters.
	PerformanceCounterInstaller	Specifies an installer for the PerformanceCounter component.
	PerformanceCounterManager	Prepares performance data for the performance.dll the system loads when working with performance counters.
	PerformanceCounterPermission	Allows control of code access permissions for PerformanceCounter.
	PerformanceCounterPermissionAttribute	Allows declaritive performance counter permission checks.
	PerformanceCounterPermissionEntry	Defines the smallest unit of a code access security permission that is set for a PerformanceCounter.
	PerformanceCounterPermissionEntryCollection	Contains a strongly typed collection of PerformanceCounterPermissionEntry objects.
	Process	Provides access to local and remote processes and enables you to start and stop local system processes.
	ProcessModule	Represents a.dll or .exe file that is loaded into a particular process.
	ProcessModuleCollection	Provides a strongly typed collection of ProcessModule objects.
	ProcessStartInfo	Specifies a set of values used when starting a process.
	ProcessThread	Represents an operating system process thread.
	ProcessThreadCollection	Provides a strongly typed collection of ProcessThread objects.
	SourceFilter	Indicates whether a listener should trace a message based on the source of a trace.
	SourceSwitch	Provides a multilevel switch to control tracing and debug output without recompiling your code.
	StackFrame	Provides information about a StackFrame, which represents a function call on the call stack for the current thread.
	StackTrace	Represents a stack trace, which is an ordered collection of one or more stack frames.
	Stopwatch	Provides a set of methods and properties that you can use to accurately measure elapsed time.
	Switch	Provides an abstract base class to create new debugging and tracing switches.
	SwitchAttribute	Identifies a switch used in an assembly, class, or member.
	SwitchLevelAttribute	Identifies the level type for a switch.
	TextWriterTraceListener	Directs tracing or debugging output to a TextWriter or to a Stream, such as FileStream.
	Trace	Provides a set of methods and properties that help you trace the execution of your code. This class cannot be inherited.
	TraceEventCache	Provides trace event data specific to a thread and a process.
	TraceFilter	Provides the base class for trace filter implementations.
	TraceListener	Provides the abstract base class for the listeners who monitor trace and debug output.
	TraceListenerCollection	Provides a thread-safe list of TraceListener objects.
	TraceSource	Provides a set of methods and properties that enable applications to trace the execution of code and associate trace messages with their source.
	TraceSwitch	Provides a multilevel switch to control tracing and debug output without recompiling your code.
	XmlWriterTraceListener	Directs tracing or debugging output as XML-encoded data to a TextWriter or to a Stream, such as a FileStream.

Interfaces

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	Interface	Description
	ICollectData	Prepares performance data for the performance.dll the system loads when working with performance counters.

Structures

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	Structure	Description
	CounterSample	Defines a structure holding the raw data for a performance counter.

Delegates

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	Delegate	Description
	DataReceivedEventHandler	Represents the method that will handle the OutputDataReceived event or ErrorDataReceived event of a Process.
	EntryWrittenEventHandler	Represents the method that will handle the EntryWritten event of an EventLog.

Enumerations

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	Enumeration	Description
	DebuggableAttribute.DebuggingModes	Specifies the debugging mode for the just-in-time (JIT) compiler.
	DebuggerBrowsableState	Provides display instructions for the debugger.
	EventLogEntryType	Specifies the event type of an event log entry.
	EventLogPermissionAccess	Defines access levels used by EventLog permission classes.
	OverflowAction	Specifies how to handle entries in an event log that has reached its maximum file size.
	PerformanceCounterCategoryType	Indicates whether the performance counter category can have multiple instances.
	PerformanceCounterInstanceLifetime	Specifies the lifetime of a performance counter instance.
	PerformanceCounterPermissionAccess	Defines access levels used by PerformanceCounter permission classes.
	PerformanceCounterType	Specifies the formula used to calculate the NextValue method for a PerformanceCounter instance.
	ProcessPriorityClass	Indicates the priority that the system associates with a process. This value, together with the priority value of each thread of the process, determines each thread's base priority level.
	ProcessWindowStyle	Specified how a new window should appear when the system starts a process.
	SourceLevels	Specifies the levels of trace messages filtered by the source switch and event type filter.
	ThreadPriorityLevel	Specifies the priority level of a thread.
	ThreadState	Specifies the current execution state of the thread.
	ThreadWaitReason	Specifies the reason a thread is waiting.
	TraceEventType	Identifies the type of event that has caused the trace.
	TraceLevel	Specifies what messages to output for the Debug, Trace and TraceSwitch classes.
	TraceOptions	Specifies trace data options to be written to the trace output.