Expose OSThreadId and TimeStamp on EventWrittenEventArgs (#19002)

* Add EventWrittenEventArgs public properties OSThreadId and TimeStamp and plumb through OSThreadId.

* Plumb ActivityId and RelatedActivityId to EventListener.

15 files changed, 335 insertions, 43 deletions

diff --git a/src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventSource.cs b/src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventSource.cs
index 6ee5f25f84..9ebb1030b8 100644
--- a/src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventSource.cs
+++ b/src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventSource.cs
@@ -1913,13 +1913,25 @@ namespace System.Diagnostics.Tracing
                         // Maintain old behavior - object identity is preserved
                         if (AppContextSwitches.PreserveEventListnerObjectIdentity)
                         {
-                            WriteToAllListeners(eventId, pActivityId, childActivityID, args);
+                            WriteToAllListeners(
+                                eventId: eventId,
+                                osThreadId: null,
+                                timeStamp: null,
+                                activityID: pActivityId,
+                                childActivityID: childActivityID,
+                                args: args);
                         }
                         else
 #endif // !ES_BUILD_STANDALONE
                         {
                             object[] serializedArgs = SerializeEventArgs(eventId, args);
-                            WriteToAllListeners(eventId, pActivityId, childActivityID, serializedArgs);
+                            WriteToAllListeners(
+                                eventId: eventId,
+                                osThreadId: null,
+                                timeStamp: null,
+                                activityID: pActivityId,
+                                childActivityID: childActivityID,
+                                args: serializedArgs);
                         }
                     }
                 }
@@ -2021,14 +2033,24 @@ namespace System.Diagnostics.Tracing
             EventSource.EventData* dataPtr = data;
             for (int i = 0; i < paramCount; i++)
                 args[i] = DecodeObject(eventId, i, ref dataPtr);
-            WriteToAllListeners(eventId, activityID, childActivityID, args);
+            WriteToAllListeners(
+                eventId: eventId,
+                osThreadId: null,
+                timeStamp: null,
+                activityID: activityID,
+                childActivityID: childActivityID,
+                args: args);
         }
 
         // helper for writing to all EventListeners attached the current eventSource.  
-        internal unsafe void WriteToAllListeners(int eventId, Guid* activityID, Guid* childActivityID, params object[] args)
+        internal unsafe void WriteToAllListeners(int eventId, uint* osThreadId, DateTime* timeStamp, Guid* activityID, Guid* childActivityID, params object[] args)
         {
             EventWrittenEventArgs eventCallbackArgs = new EventWrittenEventArgs(this);
             eventCallbackArgs.EventId = eventId;
+            if (osThreadId != null)
+                eventCallbackArgs.OSThreadId = (int)*osThreadId;
+            if (timeStamp != null)
+                eventCallbackArgs.TimeStamp = *timeStamp;
             if (activityID != null)
                 eventCallbackArgs.ActivityId = *activityID;
             if (childActivityID != null)
@@ -4609,16 +4631,47 @@ namespace System.Diagnostics.Tracing
             }
         }
 
-#region private
+        /// <summary>
+        /// Gets the identifier for the OS thread that wrote the event.
+        /// </summary>
+        public long OSThreadId
+        {
+            get
+            {
+                if (!m_osThreadId.HasValue)
+                {
+                    m_osThreadId = (long)RuntimeThread.CurrentOSThreadId;
+                }
+
+                return m_osThreadId.Value;
+            }
+            internal set
+            {
+                m_osThreadId = value;
+            }
+        }
+
+        /// <summary>
+        /// Gets a UTC DateTime that specifies when the event was written.
+        /// </summary>
+        public DateTime TimeStamp
+        {
+            get;
+            internal set;
+        }
+
+        #region private
         internal EventWrittenEventArgs(EventSource eventSource)
         {
             m_eventSource = eventSource;
+            TimeStamp = DateTime.UtcNow;
         }
         private string m_message;
         private string m_eventName;
         private EventSource m_eventSource;
         private ReadOnlyCollection<string> m_payloadNames;
         private Guid m_activityId;
+        private long? m_osThreadId;
         internal EventTags m_tags;
         internal EventOpcode m_opcode;
         internal EventLevel m_level;
diff --git a/src/System.Private.CoreLib/src/Internal/Runtime/Augments/RuntimeThread.cs b/src/System.Private.CoreLib/src/Internal/Runtime/Augments/RuntimeThread.cs
index 9a2204bf24..c613b2c01b 100644
--- a/src/System.Private.CoreLib/src/Internal/Runtime/Augments/RuntimeThread.cs
+++ b/src/System.Private.CoreLib/src/Internal/Runtime/Augments/RuntimeThread.cs
@@ -88,6 +88,19 @@ namespace Internal.Runtime.Augments
         private extern void SetPriorityNative(int priority);
 
         /*=========================================================================
+        ** Returns the operating system identifier for the current thread.
+        =========================================================================*/
+        internal static ulong CurrentOSThreadId
+        {
+            get
+            {
+                return GetCurrentOSThreadId();
+            }
+        }
+        [DllImport(JitHelpers.QCall)]
+        private static extern ulong GetCurrentOSThreadId();
+
+        /*=========================================================================
         ** Return the thread state as a consistent set of bits.  This is more
         ** general then IsAlive or IsBackground.
         =========================================================================*/
diff --git a/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/DotNETRuntimeEventSource.cs b/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/DotNETRuntimeEventSource.cs
index 8bfac2b04b..42cf77959b 100644
--- a/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/DotNETRuntimeEventSource.cs
+++ b/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/DotNETRuntimeEventSource.cs
@@ -16,7 +16,7 @@ namespace System.Diagnostics.Tracing
         /// <param name="eventID">The eventID corresponding to the event as defined in the auto-generated portion of the RuntimeEventSource class.</param>
         /// <param name="payload">A span pointing to the data payload for the event.</param>
         [NonEvent]
-        internal unsafe void ProcessEvent(uint eventID, ReadOnlySpan<Byte> payload)
+        internal unsafe void ProcessEvent(uint eventID, uint osThreadID, DateTime timeStamp, Guid activityId, Guid childActivityId, ReadOnlySpan<Byte> payload)
         {
             // Make sure the eventID is valid.
             if (eventID >= m_eventData.Length)
@@ -26,7 +26,13 @@ namespace System.Diagnostics.Tracing
 
             // Decode the payload.
             object[] decodedPayloadFields = EventPipePayloadDecoder.DecodePayload(ref m_eventData[eventID], payload);
-            WriteToAllListeners((int)eventID, null, null, decodedPayloadFields);
+            WriteToAllListeners(
+                eventId: (int)eventID,
+                osThreadId: &osThreadID,
+                timeStamp: &timeStamp,
+                activityID: &activityId,
+                childActivityID: &childActivityId,
+                args: decodedPayloadFields);
         }
    }
 #endif // FEATURE_PERFTRACING
diff --git a/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/EventPipe.cs b/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/EventPipe.cs
index 89528cfd30..94ace3cca5 100644
--- a/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/EventPipe.cs
+++ b/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/EventPipe.cs
@@ -16,11 +16,23 @@ namespace System.Diagnostics.Tracing
     {
         internal IntPtr ProviderID;
         internal uint EventID;
+        internal uint ThreadID;
+        internal Int64 TimeStamp;
+        internal Guid ActivityId;
+        internal Guid ChildActivityId;
         internal IntPtr Payload;
         internal uint PayloadLength;
     }
 
     [StructLayout(LayoutKind.Sequential)]
+    internal struct EventPipeSessionInfo
+    {
+        internal Int64 StartTimeAsUTCFileTime;
+        internal Int64 StartTimeStamp;
+        internal Int64 TimeStampFrequency;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
     internal struct EventPipeProviderConfiguration
     {
         [MarshalAs(UnmanagedType.LPWStr)]
@@ -128,6 +140,8 @@ namespace System.Diagnostics.Tracing
 
     internal static class EventPipe
     {
+        private static UInt64 s_sessionID = 0;
+
         internal static void Enable(EventPipeConfiguration configuration)
         {
             if(configuration == null)
@@ -142,7 +156,7 @@ namespace System.Diagnostics.Tracing
 
             EventPipeProviderConfiguration[] providers = configuration.Providers;
 
-            EventPipeInternal.Enable(
+            s_sessionID = EventPipeInternal.Enable(
                 configuration.OutputFile,
                 configuration.CircularBufferSizeInMB,
                 configuration.ProfilerSamplingRateInNanoseconds,
@@ -152,7 +166,7 @@ namespace System.Diagnostics.Tracing
 
         internal static void Disable()
         {
-            EventPipeInternal.Disable();
+            EventPipeInternal.Disable(s_sessionID);
         }
     }
 
@@ -162,10 +176,10 @@ namespace System.Diagnostics.Tracing
         // These PInvokes are used by the configuration APIs to interact with EventPipe.
         //
         [DllImport(JitHelpers.QCall, CharSet = CharSet.Unicode)]
-        internal static extern void Enable(string outputFile, uint circularBufferSizeInMB, long profilerSamplingRateInNanoseconds, EventPipeProviderConfiguration[] providers, int numProviders);
+        internal static extern UInt64 Enable(string outputFile, uint circularBufferSizeInMB, long profilerSamplingRateInNanoseconds, EventPipeProviderConfiguration[] providers, int numProviders);
 
         [DllImport(JitHelpers.QCall, CharSet = CharSet.Unicode)]
-        internal static extern void Disable();
+        internal static extern void Disable(UInt64 sessionID);
 
         //
         // These PInvokes are used by EventSource to interact with the EventPipe.
@@ -191,6 +205,13 @@ namespace System.Diagnostics.Tracing
         [DllImport(JitHelpers.QCall, CharSet = CharSet.Unicode)]
         internal static extern unsafe void WriteEventData(IntPtr eventHandle, uint eventID, EventProvider.EventData* pEventData, uint dataCount, Guid* activityId, Guid* relatedActivityId);
 
+
+        //
+        // These PInvokes are used as part of the EventPipeEventDispatcher.
+        //
+        [DllImport(JitHelpers.QCall, CharSet = CharSet.Unicode)]
+        internal static extern unsafe bool GetSessionInfo(UInt64 sessionID, EventPipeSessionInfo* pSessionInfo);
+
         [DllImport(JitHelpers.QCall, CharSet = CharSet.Unicode)]
         internal static extern unsafe bool GetNextEvent(EventPipeEventInstanceData* pInstance);
     }
diff --git a/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/EventPipeEventDispatcher.cs b/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/EventPipeEventDispatcher.cs
index 7d08d0db84..f7afd973c1 100644
--- a/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/EventPipeEventDispatcher.cs
+++ b/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/EventPipeEventDispatcher.cs
@@ -26,6 +26,11 @@ namespace System.Diagnostics.Tracing
 
         private IntPtr m_RuntimeProviderID;
 
+        private UInt64 m_sessionID = 0;
+        private DateTime m_syncTimeUtc;
+        private Int64 m_syncTimeQPC;
+        private Int64 m_timeQPCFrequency;
+
         private bool m_stopDispatchTask;
         private Task m_dispatchTask = null;
         private object m_dispatchControlLock = new object();
@@ -73,13 +78,15 @@ namespace System.Diagnostics.Tracing
 
         private void CommitDispatchConfiguration()
         {
+            Debug.Assert(Monitor.IsEntered(m_dispatchControlLock));
+
             // Ensure that the dispatch task is stopped.
             // This is a no-op if the task is already stopped.
             StopDispatchTask();
 
             // Stop tracing.
             // This is a no-op if it's already disabled.
-            EventPipeInternal.Disable();
+            EventPipeInternal.Disable(m_sessionID);
 
             // Check to see if tracing should be enabled.
             if (m_subscriptions.Count <= 0)
@@ -87,7 +94,7 @@ namespace System.Diagnostics.Tracing
                 return;
             }
 
-            // Start collecting events.
+            // Determine the keywords and level that should be used based on the set of enabled EventListeners.
             EventKeywords aggregatedKeywords = EventKeywords.None;
             EventLevel highestLevel = EventLevel.LogAlways;
 
@@ -97,12 +104,28 @@ namespace System.Diagnostics.Tracing
                 highestLevel = (subscription.Level > highestLevel) ? subscription.Level : highestLevel;
             }
 
+            // Enable the EventPipe session.
             EventPipeProviderConfiguration[] providerConfiguration = new EventPipeProviderConfiguration[]
             {
                 new EventPipeProviderConfiguration(RuntimeEventSource.EventSourceName, (ulong) aggregatedKeywords, (uint) highestLevel)
             };
 
-            EventPipeInternal.Enable(null, 1024, 1, providerConfiguration, 1);
+            m_sessionID = EventPipeInternal.Enable(null, 1024, 1, providerConfiguration, 1);
+            Debug.Assert(m_sessionID != 0);
+
+            // Get the session information that is required to properly dispatch events.
+            EventPipeSessionInfo sessionInfo;
+            unsafe
+            {
+                if (!EventPipeInternal.GetSessionInfo(m_sessionID, &sessionInfo))
+                {
+                    Debug.Assert(false, "GetSessionInfo returned false.");
+                }
+            }
+
+            m_syncTimeUtc = DateTime.FromFileTimeUtc(sessionInfo.StartTimeAsUTCFileTime);
+            m_syncTimeQPC = sessionInfo.StartTimeStamp;
+            m_timeQPCFrequency = sessionInfo.TimeStampFrequency;
 
             // Start the dispatch task.
             StartDispatchTask();
@@ -146,7 +169,8 @@ namespace System.Diagnostics.Tracing
                     {
                         // Dispatch the event.
                         ReadOnlySpan<Byte> payload = new ReadOnlySpan<byte>((void*)instanceData.Payload, (int)instanceData.PayloadLength);
-                        RuntimeEventSource.Log.ProcessEvent(instanceData.EventID, payload);
+                        DateTime dateTimeStamp = TimeStampToDateTime(instanceData.TimeStamp);
+                        RuntimeEventSource.Log.ProcessEvent(instanceData.EventID, instanceData.ThreadID, dateTimeStamp, instanceData.ActivityId, instanceData.ChildActivityId, payload);
                     }
                 }
 
@@ -157,6 +181,26 @@ namespace System.Diagnostics.Tracing
                 }
             }
         }
+
+        /// <summary>
+        /// Converts a QueryPerformanceCounter (QPC) timestamp to a UTC DateTime.
+        /// </summary>
+        private DateTime TimeStampToDateTime(Int64 timeStamp)
+        {
+            if (timeStamp == Int64.MaxValue)
+            {
+                return DateTime.MaxValue;
+            }
+
+            Debug.Assert((m_syncTimeUtc.Ticks != 0) && (m_syncTimeQPC != 0) && (m_timeQPCFrequency != 0));
+            Int64 inTicks = (Int64)((timeStamp - m_syncTimeQPC) * 10000000.0 / m_timeQPCFrequency) + m_syncTimeUtc.Ticks;
+            if((inTicks < 0)|| (DateTime.MaxTicks < inTicks))
+            {
+                inTicks = DateTime.MaxTicks;
+            }
+
+            return new DateTime(inTicks, DateTimeKind.Utc);
+        }
     }
 #endif // FEATURE_PERFTRACING
 }
diff --git a/src/pal/inc/pal.h b/src/pal/inc/pal.h
index 98d0ae2f11..993d76ed9e 100644
--- a/src/pal/inc/pal.h
+++ b/src/pal/inc/pal.h
@@ -1267,6 +1267,12 @@ PALAPI
 GetCurrentThreadId(
            VOID);
 
+PALIMPORT
+size_t
+PALAPI
+PAL_GetCurrentOSThreadId(
+           VOID);
+
 // To work around multiply-defined symbols in the Carbon framework.
 #define GetCurrentThread PAL_GetCurrentThread
 PALIMPORT
diff --git a/src/pal/src/thread/thread.cpp b/src/pal/src/thread/thread.cpp
index bc06d2f7d4..66311edb03 100644
--- a/src/pal/src/thread/thread.cpp
+++ b/src/pal/src/thread/thread.cpp
@@ -399,6 +399,31 @@ GetCurrentThreadId(
     return dwThreadId;
 }
 
+/*++
+Function:
+  PAL_GetCurrentOSThreadId
+
+Returns the current thread's OS thread ID.
+This API is functionally equivalent to GetCurrentThreadId, but does not truncate the return value to 32-bits.
+This is needed to ensure that we can provide the correct OS thread ID on platforms such as OSX that have a 64-bit thread ID.
+--*/
+size_t
+PALAPI
+PAL_GetCurrentOSThreadId(
+            VOID)
+{
+    size_t threadId;
+
+    PERF_ENTRY(PAL_GetCurrentOSThreadId);
+    ENTRY("PAL_GetCurrentOSThreadId()\n");
+
+    threadId = THREADSilentGetCurrentThreadId();
+    
+    LOGEXIT("PAL_GetCurrentOSThreadId returns %p\n", threadId);    
+    PERF_EXIT(GetCurrentThreadId);
+    
+    return threadId;
+}
 
 
 /*++
diff --git a/src/vm/comcallablewrapper.cpp b/src/vm/comcallablewrapper.cpp
index 15e02a214b..a2186a78b1 100644
--- a/src/vm/comcallablewrapper.cpp
+++ b/src/vm/comcallablewrapper.cpp
@@ -958,18 +958,24 @@ void SimpleComCallWrapper::BuildRefCountLogMessage(LPCWSTR wszOperation, StackSS
 
         if (ETW_EVENT_ENABLED(MICROSOFT_WINDOWS_DOTNETRUNTIME_PRIVATE_PROVIDER_Context, CCWRefCountChange)) 
         {
-            SString className;
-            className.SetUTF8(pszClassName);
-            SString nameSpace;
-            nameSpace.SetUTF8(pszNamespace);
-
-            FireEtwCCWRefCountChange(
-                handle, 
-                (Object *)obj, 
-                this, 
-                dwEstimatedRefCount, 
-                NULL,                   // domain value is not interesting in CoreCLR
-                className.GetUnicode(), nameSpace.GetUnicode(), wszOperation, GetClrInstanceId());
+            EX_TRY
+            {
+                SString className;
+                className.SetUTF8(pszClassName);
+                SString nameSpace;
+                nameSpace.SetUTF8(pszNamespace);
+
+                FireEtwCCWRefCountChange(
+                    handle, 
+                    (Object *)obj, 
+                    this, 
+                    dwEstimatedRefCount, 
+                    NULL,                   // domain value is not interesting in CoreCLR
+                    className.GetUnicode(), nameSpace.GetUnicode(), wszOperation, GetClrInstanceId());
+            }
+            EX_CATCH
+            { }
+            EX_END_CATCH(SwallowAllExceptions);
         }
         
         if (g_pConfig->ShouldLogCCWRefCountChange(pszClassName, pszNamespace))
diff --git a/src/vm/comsynchronizable.cpp b/src/vm/comsynchronizable.cpp
index a476a77609..0a6447bd9b 100644
--- a/src/vm/comsynchronizable.cpp
+++ b/src/vm/comsynchronizable.cpp
@@ -804,6 +804,27 @@ FCIMPL0(Object*, ThreadNative::GetCurrentThread)
 }
 FCIMPLEND
 
+UINT64 QCALLTYPE ThreadNative::GetCurrentOSThreadId()
+{
+    QCALL_CONTRACT;
+
+    // The Windows API GetCurrentThreadId returns a 32-bit integer thread ID.
+    // On some non-Windows platforms (e.g. OSX), the thread ID is a 64-bit value.
+    // We special case the API for non-Windows to get the 64-bit value and zero-extend
+    // the Windows value to return a single data type on all platforms.
+
+    UINT64 threadId;
+
+    BEGIN_QCALL;
+#ifndef FEATURE_PAL
+    threadId = (UINT64) GetCurrentThreadId();
+#else
+    threadId = (UINT64) PAL_GetCurrentOSThreadId();
+#endif
+    END_QCALL;
+
+    return threadId;
+}
 
 FCIMPL3(void, ThreadNative::SetStart, ThreadBaseObject* pThisUNSAFE, Object* pDelegateUNSAFE, INT32 iRequestedStackSize)
 {
diff --git a/src/vm/comsynchronizable.h b/src/vm/comsynchronizable.h
index 87321fd336..ddd55cc21f 100644
--- a/src/vm/comsynchronizable.h
+++ b/src/vm/comsynchronizable.h
@@ -101,6 +101,7 @@ public:
     static FCDECL1(void,    SpinWait,                       int iterations);
     static BOOL QCALLTYPE YieldThread();
     static FCDECL0(Object*, GetCurrentThread);
+    static UINT64 QCALLTYPE GetCurrentOSThreadId();
     static FCDECL1(void,    Finalize,                       ThreadBaseObject* pThis);
 #ifdef FEATURE_COMINTEROP
     static FCDECL1(void,    DisableComObjectEagerCleanup,   ThreadBaseObject* pThis);
diff --git a/src/vm/ecalllist.h b/src/vm/ecalllist.h
index 25bc85abce..46ee7f8c5f 100644
--- a/src/vm/ecalllist.h
+++ b/src/vm/ecalllist.h
@@ -668,6 +668,7 @@ FCFuncStart(gRuntimeThreadFuncs)
     FCFuncElement("get_IsThreadPoolThread", ThreadNative::IsThreadpoolThread)
     FCFuncElement("GetPriorityNative", ThreadNative::GetPriority)
     FCFuncElement("SetPriorityNative", ThreadNative::SetPriority)
+    QCFuncElement("GetCurrentOSThreadId", ThreadNative::GetCurrentOSThreadId)
     FCFuncElement("GetThreadStateNative", ThreadNative::GetThreadState)
 #ifdef FEATURE_COMINTEROP_APARTMENT_SUPPORT
     FCFuncElement("GetApartmentStateNative", ThreadNative::GetApartmentState)
@@ -1154,6 +1155,7 @@ FCFuncEnd()
 FCFuncStart(gEventPipeInternalFuncs)
     QCFuncElement("Enable", EventPipeInternal::Enable)
     QCFuncElement("Disable", EventPipeInternal::Disable)
+    QCFuncElement("GetSessionInfo", EventPipeInternal::GetSessionInfo)
     QCFuncElement("CreateProvider", EventPipeInternal::CreateProvider)
     QCFuncElement("DefineEvent", EventPipeInternal::DefineEvent)
     QCFuncElement("DeleteProvider", EventPipeInternal::DeleteProvider)
diff --git a/src/vm/eventpipe.cpp b/src/vm/eventpipe.cpp
index 955c757790..42eea423a7 100644
--- a/src/vm/eventpipe.cpp
+++ b/src/vm/eventpipe.cpp
@@ -250,7 +250,7 @@ void EventPipe::Shutdown()
     // We are shutting down, so if disabling EventPipe throws, we need to move along anyway.
     EX_TRY
     {
-        Disable();
+        Disable((EventPipeSessionID)s_pSession);
     }
     EX_CATCH { }
     EX_END_CATCH(SwallowAllExceptions);
@@ -279,7 +279,7 @@ void EventPipe::Shutdown()
 #endif
 }
 
-void EventPipe::Enable(
+EventPipeSessionID EventPipe::Enable(
     LPCWSTR strOutputPath,
     unsigned int circularBufferSizeInMB,
     EventPipeProviderConfiguration *pProviders,
@@ -301,10 +301,10 @@ void EventPipe::Enable(
         static_cast<unsigned int>(numProviders));
 
     // Enable the session.
-    Enable(strOutputPath, pSession);
+    return Enable(strOutputPath, pSession);
 }
 
-void EventPipe::Enable(LPCWSTR strOutputPath, EventPipeSession *pSession)
+EventPipeSessionID EventPipe::Enable(LPCWSTR strOutputPath, EventPipeSession *pSession)
 {
     CONTRACTL
     {
@@ -318,13 +318,13 @@ void EventPipe::Enable(LPCWSTR strOutputPath, EventPipeSession *pSession)
     // If tracing is not initialized or is already enabled, bail here.
     if(!s_tracingInitialized || s_pConfig == NULL || s_pConfig->Enabled())
     {
-        return;
+        return 0;
     }
 
     // If the state or arguments are invalid, bail here.
     if(pSession == NULL || !pSession->IsValid())
     {
-        return;
+        return 0;
     }
 
     // Enable the EventPipe EventSource.
@@ -365,9 +365,12 @@ void EventPipe::Enable(LPCWSTR strOutputPath, EventPipeSession *pSession)
 
     // Enable the sample profiler
     SampleProfiler::Enable();
+
+    // Return the session ID.
+    return (EventPipeSessionID)s_pSession;
 }
 
-void EventPipe::Disable()
+void EventPipe::Disable(EventPipeSessionID id)
 {
     CONTRACTL
     {
@@ -377,6 +380,13 @@ void EventPipe::Disable()
     }
     CONTRACTL_END;
 
+    // Only perform the disable operation if the session ID
+    // matches the current active session.
+    if(id != (EventPipeSessionID)s_pSession)
+    {
+        return;
+    }
+
     // Don't block GC during clean-up.
     GCX_PREEMP();
 
@@ -463,6 +473,18 @@ void EventPipe::Disable()
     }
 }
 
+EventPipeSession* EventPipe::GetSession(EventPipeSessionID id)
+{
+    LIMITED_METHOD_CONTRACT;
+
+    EventPipeSession *pSession = NULL;
+    if((EventPipeSessionID)s_pSession == id)
+    {
+        pSession = s_pSession;
+    }
+    return pSession;
+}
+
 bool EventPipe::Enabled()
 {
     LIMITED_METHOD_CONTRACT;
@@ -1026,7 +1048,7 @@ EventPipeEventInstance* EventPipe::GetNextEvent()
     return pInstance;
 }
 
-void QCALLTYPE EventPipeInternal::Enable(
+UINT64 QCALLTYPE EventPipeInternal::Enable(
         __in_z LPCWSTR outputFile,
         UINT32 circularBufferSizeInMB,
         INT64 profilerSamplingRateInNanoseconds,
@@ -1035,21 +1057,48 @@ void QCALLTYPE EventPipeInternal::Enable(
 {
     QCALL_CONTRACT;
 
+    UINT64 sessionID = 0;
+
     BEGIN_QCALL;
     SampleProfiler::SetSamplingRate((unsigned long)profilerSamplingRateInNanoseconds);
-    EventPipe::Enable(outputFile, circularBufferSizeInMB, pProviders, numProviders);
+    sessionID = EventPipe::Enable(outputFile, circularBufferSizeInMB, pProviders, numProviders);
     END_QCALL;
+
+    return sessionID;
 }
 
-void QCALLTYPE EventPipeInternal::Disable()
+void QCALLTYPE EventPipeInternal::Disable(UINT64 sessionID)
 {
     QCALL_CONTRACT;
 
     BEGIN_QCALL;
-    EventPipe::Disable();
+    EventPipe::Disable(sessionID);
     END_QCALL;
 }
 
+bool QCALLTYPE EventPipeInternal::GetSessionInfo(UINT64 sessionID, EventPipeSessionInfo *pSessionInfo)
+{
+    QCALL_CONTRACT;
+
+    bool retVal = false;
+    BEGIN_QCALL;
+
+    if(pSessionInfo != NULL)
+    {
+        EventPipeSession *pSession = EventPipe::GetSession(sessionID);
+        if(pSession != NULL)
+        {
+            pSessionInfo->StartTimeAsUTCFileTime = pSession->GetStartTime();
+            pSessionInfo->StartTimeStamp.QuadPart = pSession->GetStartTimeStamp().QuadPart;
+            QueryPerformanceFrequency(&pSessionInfo->TimeStampFrequency);
+            retVal = true;
+        }
+    }
+
+    END_QCALL;
+    return retVal;
+}
+
 INT_PTR QCALLTYPE EventPipeInternal::CreateProvider(
     __in_z LPCWSTR providerName,
     EventPipeCallback pCallbackFunc)
@@ -1235,6 +1284,10 @@ bool QCALLTYPE EventPipeInternal::GetNextEvent(
     {
         pInstance->ProviderID = pNextInstance->GetEvent()->GetProvider();
         pInstance->EventID = pNextInstance->GetEvent()->GetEventID();
+        pInstance->ThreadID = pNextInstance->GetThreadId();
+        pInstance->TimeStamp.QuadPart = pNextInstance->GetTimeStamp()->QuadPart;
+        pInstance->ActivityId = *pNextInstance->GetActivityId();
+        pInstance->RelatedActivityId = *pNextInstance->GetRelatedActivityId();
         pInstance->Payload = pNextInstance->GetData();
         pInstance->PayloadLength = pNextInstance->GetDataLength();
     }
diff --git a/src/vm/eventpipe.h b/src/vm/eventpipe.h
index 1904d45d6c..d5273c4974 100644
--- a/src/vm/eventpipe.h
+++ b/src/vm/eventpipe.h
@@ -215,6 +215,8 @@ public:
     }
 };
 
+typedef UINT64 EventPipeSessionID;
+
 class EventPipe
 {
     // Declare friends.
@@ -236,14 +238,17 @@ class EventPipe
         static void EnableOnStartup();
 
         // Enable tracing via the event pipe.
-        static void Enable(
+        static EventPipeSessionID Enable(
             LPCWSTR strOutputPath,
             unsigned int circularBufferSizeInMB,
             EventPipeProviderConfiguration *pProviders,
             int numProviders);
 
         // Disable tracing via the event pipe.
-        static void Disable();
+        static void Disable(EventPipeSessionID id);
+
+        // Get the session for the specified session ID.
+        static EventPipeSession* GetSession(EventPipeSessionID id);
 
         // Specifies whether or not the event pipe is enabled.
         static bool Enabled();
@@ -288,7 +293,7 @@ class EventPipe
     private:
 
         // Enable the specified EventPipe session.
-        static void Enable(LPCWSTR strOutputPath, EventPipeSession *pSession);
+        static EventPipeSessionID Enable(LPCWSTR strOutputPath, EventPipeSession *pSession);
 
         // Get the EnableOnStartup configuration from environment.
         static void GetConfigurationFromEnvironment(SString &outputPath, EventPipeSession *pSession);
@@ -385,20 +390,34 @@ private:
     public:
         void *ProviderID;
         unsigned int EventID;
+        unsigned int ThreadID;
+        LARGE_INTEGER TimeStamp;
+        GUID ActivityId;
+        GUID RelatedActivityId;
         const BYTE *Payload;
         unsigned int PayloadLength;
     };
 
+    struct EventPipeSessionInfo
+    {
+    public:
+        FILETIME StartTimeAsUTCFileTime;
+        LARGE_INTEGER StartTimeStamp;
+        LARGE_INTEGER TimeStampFrequency;
+    };
+
 public:
 
-    static void QCALLTYPE Enable(
+    static UINT64 QCALLTYPE Enable(
         __in_z LPCWSTR outputFile,
         UINT32 circularBufferSizeInMB,
         INT64 profilerSamplingRateInNanoseconds,
         EventPipeProviderConfiguration *pProviders,
         INT32 numProviders);
 
-    static void QCALLTYPE Disable();
+    static void QCALLTYPE Disable(UINT64 sessionID);
+
+    static bool QCALLTYPE GetSessionInfo(UINT64 sessionID, EventPipeSessionInfo *pSessionInfo);
 
     static INT_PTR QCALLTYPE CreateProvider(
         __in_z LPCWSTR providerName,
diff --git a/src/vm/eventpipesession.cpp b/src/vm/eventpipesession.cpp
index 5f6e415662..b10caf2f5b 100644
--- a/src/vm/eventpipesession.cpp
+++ b/src/vm/eventpipesession.cpp
@@ -29,6 +29,8 @@ EventPipeSession::EventPipeSession(
     m_pProviderList = new EventPipeSessionProviderList(
         pProviders,
         numProviders);
+    GetSystemTimeAsFileTime(&m_sessionStartTime);
+    QueryPerformanceCounter(&m_sessionStartTimeStamp);
 }
 
 EventPipeSession::~EventPipeSession()
diff --git a/src/vm/eventpipesession.h b/src/vm/eventpipesession.h
index c8c2e1ff1b..5518e76097 100644
--- a/src/vm/eventpipesession.h
+++ b/src/vm/eventpipesession.h
@@ -34,6 +34,12 @@ private:
     // This determines behavior within the system (e.g. policies around which events to drop, etc.)
     EventPipeSessionType m_sessionType;
 
+    // Start date and time in UTC.
+    FILETIME m_sessionStartTime;
+
+    // Start timestamp.
+    LARGE_INTEGER m_sessionStartTimeStamp;
+
 public:
 
     // TODO: This needs to be exposed via EventPipe::CreateSession() and EventPipe::DeleteSession() to avoid memory ownership issues.
@@ -76,6 +82,20 @@ public:
         m_rundownEnabled = value;
     }
 
+    // Get the session start time in UTC.
+    FILETIME GetStartTime() const
+    {
+        LIMITED_METHOD_CONTRACT;
+        return m_sessionStartTime;
+    }
+
+    // Get the session start timestamp.
+    LARGE_INTEGER GetStartTimeStamp() const
+    {
+        LIMITED_METHOD_CONTRACT;
+        return m_sessionStartTimeStamp;
+    }
+
     // Enable all events.
     // This is used for testing and is controlled via COMPLUS_EnableEventPipe.
     void EnableAllEvents();