address pr comments

documentation/sphinx/source/api-c.rst

@@ -481,7 +481,11 @@ An |database-blurb1| Modifications to a database are performed via transactions.
          |length-of| ``snapshot_command``
    
    .. note:: The function is exposing the functionality of the fdbcli command ``snapshot``. Please take a look at the documentation before using (see :ref:`disk-snapshot-backups`).
-         
+
+.. function:: double fdb_database_get_main_thread_busyness(FDBDatabase* database)
+
+   Returns a value between `0` and `1` representing the percentage of time the Network Thread is busy executing work from the TaskQueue. This value is updated every second.
+
 Transaction
 ===========
 

fdbclient/NativeAPI.actor.cpp

@@ -1733,6 +1733,33 @@ void setNetworkOption(FDBNetworkOptions::Option option, Optional<StringRef> valu
 	}
 }
 
+// update the network busyness on a 1s cadence
+ACTOR Future<Void> monitorNetworkBusyness() {
+	state double prevTime = now();
+	loop choose {
+		when(wait(delay(CLIENT_KNOBS->NETWORK_BUSYNESS_MONITOR_INTERVAL, TaskPriority::FlushTrace))) {
+			double elapsed = now() - prevTime; // get elapsed time from last execution
+			prevTime = now();
+			if (!g_network->isSimulated()) {
+				struct NetworkMetrics::PriorityStats& itr =
+				    g_network->networkInfo.metrics.starvationTrackerNetworkBusyness;
+
+				if (itr.active) { // update metrics
+					itr.duration += now() - itr.windowedTimer;
+					itr.maxDuration = std::max(itr.maxDuration, now() - itr.timer);
+					itr.windowedTimer = now();
+				}
+
+				g_network->networkInfo.metrics.networkBusyness =
+				    std::min(elapsed, itr.duration) / elapsed; // average duration spent doing "work"
+
+				itr.duration = 0;
+				itr.maxDuration = 0;
+			}
+		}
+	}
+}
+
 // Setup g_network and start monitoring for network busyness
 void setupNetwork(uint64_t transportId, bool useMetrics) {
 	if (g_network)
@@ -1748,8 +1775,7 @@ void setupNetwork(uint64_t transportId, bool useMetrics) {
 	FlowTransport::createInstance(true, transportId);
 	Net2FileSystem::newFileSystem();
 
-	monitorNetworkBusyness();
-	uncancellable(recurring(&monitorNetworkBusyness, CLIENT_KNOBS->NETWORK_BUSYNESS_MONITOR_INTERVAL, TaskPriority::FlushTrace));
+	uncancellable(monitorNetworkBusyness());
 }
 
 void runNetwork() {

fdbclient/ThreadSafeTransaction.cpp

@@ -93,6 +93,7 @@ ThreadFuture<Void> ThreadSafeDatabase::createSnapshot(const StringRef& uid, cons
 
 double ThreadSafeDatabase::getMainThreadBusyness() {
 	// Return the main network thread busyness
+	ASSERT(g_network);
 	return g_network->networkInfo.metrics.networkBusyness;
 }
 

flow/Net2.actor.cpp

@@ -1622,13 +1622,8 @@ void Net2::trackAtPriority(TaskPriority priority, double now) {
 			updateStarvationTrackers(binStats, priority, lastPriority, now);
 		}
 
-		// Update starvation trackers for 1s measurment interval
-		for (auto& binStats : networkInfo.metrics.starvationTrackersNetworkBusyness) {
-			if (binStats.priority > lastPriority && binStats.priority > priority) {
-				break;
-			}
-			updateStarvationTrackers(binStats, priority, lastPriority, now);
-		}
+		// Update starvation trackers for network busyness
+		updateStarvationTrackers(networkInfo.metrics.starvationTrackerNetworkBusyness, priority, lastPriority, now);
 
 		lastPriorityStats = &activeStatsItr.first->second;
 	}

flow/SystemMonitor.cpp

@@ -61,34 +61,6 @@ SystemStatistics getSystemStatistics() {
 	    .detail("ApproximateUnusedMemory" #size, FastAllocator<size>::getApproximateMemoryUnused())                    \
 	    .detail("ActiveThreads" #size, FastAllocator<size>::getActiveThreads())
 
-// update the network busyness on a 1s cadence
-void monitorNetworkBusyness() {
-	const IPAddress ipAddr = IPAddress();
-	static StatisticsState statState = StatisticsState();
-	SystemStatistics currentStats = getSystemStatistics("", &ipAddr, &(&statState)->systemState, true);
-	if (!g_network->isSimulated() && currentStats.initialized) {
-		bool firstTracker = true;
-		// iterate over the starvation trackers which are updated in Net2.actor.cpp
-		for (auto& itr : g_network->networkInfo.metrics.starvationTrackersNetworkBusyness) {
-			if (itr.active) {
-				itr.duration += now() - itr.windowedTimer;
-				itr.maxDuration = std::max(itr.maxDuration, now() - itr.timer);
-				itr.windowedTimer = now();
-			}
-
-			if (firstTracker) {
-				g_network->networkInfo.metrics.networkBusyness =
-				    std::min(currentStats.elapsed, itr.duration) /
-				    currentStats.elapsed; // average duration spent doing "work"
-				firstTracker = false;
-			}
-
-			itr.duration = 0;
-			itr.maxDuration = 0;
-		}
-	}
-}
-
 SystemStatistics customSystemMonitor(std::string eventName, StatisticsState* statState, bool machineMetrics) {
 	const IPAddress ipAddr = machineState.ip.present() ? machineState.ip.get() : IPAddress();
 	SystemStatistics currentStats = getSystemStatistics(

flow/SystemMonitor.h

@@ -148,7 +148,6 @@ struct StatisticsState {
 };
 
 void systemMonitor();
-void monitorNetworkBusyness();
 SystemStatistics customSystemMonitor(std::string eventName, StatisticsState* statState, bool machineMetrics = false);
 SystemStatistics getSystemStatistics();
 

flow/network.h

@@ -343,14 +343,16 @@ struct NetworkMetrics {
 	std::unordered_map<TaskPriority, struct PriorityStats> activeTrackers;
 	double lastRunLoopBusyness;
 	std::atomic<double> networkBusyness;
-	std::vector<struct PriorityStats> starvationTrackers, starvationTrackersNetworkBusyness;
+	std::vector<struct PriorityStats> starvationTrackers;
+	struct PriorityStats starvationTrackerNetworkBusyness;
 
 	static const std::vector<int> starvationBins;
 
-	NetworkMetrics() : lastRunLoopBusyness(0), networkBusyness(0) {
+	NetworkMetrics()
+	  : lastRunLoopBusyness(0), networkBusyness(0),
+	    starvationTrackerNetworkBusyness(PriorityStats(static_cast<TaskPriority>(starvationBins.at(0)))) {
 		for (int priority : starvationBins) {
 			starvationTrackers.emplace_back(static_cast<TaskPriority>(priority));
-			starvationTrackersNetworkBusyness.emplace_back(static_cast<TaskPriority>(priority));
 		}
 	}
 
@@ -365,7 +367,7 @@ struct NetworkMetrics {
 		lastRunLoopBusyness = rhs.lastRunLoopBusyness;
 		networkBusyness = rhs.networkBusyness.load();
 		starvationTrackers = rhs.starvationTrackers;
-		starvationTrackersNetworkBusyness = rhs.starvationTrackersNetworkBusyness;
+		starvationTrackerNetworkBusyness = rhs.starvationTrackerNetworkBusyness;
 		return *this;
 	}
 };