diff --git a/node/src/main/kotlin/net/corda/node/services/statemachine/MultiThreadedStateMachineManager.kt b/node/src/main/kotlin/net/corda/node/services/statemachine/MultiThreadedStateMachineManager.kt
index 7cc94b361e..9669251b89 100644
--- a/node/src/main/kotlin/net/corda/node/services/statemachine/MultiThreadedStateMachineManager.kt
+++ b/node/src/main/kotlin/net/corda/node/services/statemachine/MultiThreadedStateMachineManager.kt
@@ -52,6 +52,7 @@ import java.security.SecureRandom
 import java.util.*
 import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.ExecutorService
+import java.util.concurrent.ThreadPoolExecutor
 import javax.annotation.concurrent.ThreadSafe
 import kotlin.collections.ArrayList
 import kotlin.streams.toList
@@ -132,7 +133,8 @@ class MultiThreadedStateMachineManager(
         this.actionExecutor = makeActionExecutor(checkpointSerializationContext)
         fiberDeserializationChecker?.start(checkpointSerializationContext)
         val fibers = restoreFlowsFromCheckpoints()
-        metrics.register("Flows.InFlight", Gauge<Int> { concurrentBox.content.flows.size })
+        metrics.register("Flows.ActiveThreads", Gauge { (executor as? ThreadPoolExecutor)?.activeCount })
+        metrics.register("Flows.InFlight", Gauge { concurrentBox.content.flows.size })
         Fiber.setDefaultUncaughtExceptionHandler { fiber, throwable ->
             (fiber as FlowStateMachineImpl<*>).logger.warn("Caught exception from flow", throwable)
         }
@@ -625,6 +627,7 @@ class MultiThreadedStateMachineManager(
         interceptors.add { HospitalisingInterceptor(PropagatingFlowHospital, it) }
         if (serviceHub.configuration.devMode) {
             interceptors.add { DumpHistoryOnErrorInterceptor(it) }
+            interceptors.add { MetricInterceptor(metrics, it) }
         }
         if (serviceHub.configuration.shouldCheckCheckpoints()) {
             interceptors.add { FiberDeserializationCheckingInterceptor(fiberDeserializationChecker!!, it) }
diff --git a/node/src/main/kotlin/net/corda/node/services/statemachine/interceptors/MetricInterceptor.kt b/node/src/main/kotlin/net/corda/node/services/statemachine/interceptors/MetricInterceptor.kt
new file mode 100644
index 0000000000..f5e298fed8
--- /dev/null
+++ b/node/src/main/kotlin/net/corda/node/services/statemachine/interceptors/MetricInterceptor.kt
@@ -0,0 +1,24 @@
+package net.corda.node.services.statemachine.interceptors
+
+import co.paralleluniverse.fibers.Suspendable
+import com.codahale.metrics.MetricRegistry
+import net.corda.node.services.statemachine.*
+import net.corda.node.services.statemachine.transitions.FlowContinuation
+import net.corda.node.services.statemachine.transitions.TransitionResult
+
+class MetricInterceptor(val metrics: MetricRegistry, val delegate: TransitionExecutor): TransitionExecutor {
+    @Suspendable
+    override fun executeTransition(fiber: FlowFiber, previousState: StateMachineState, event: Event, transition: TransitionResult, actionExecutor: ActionExecutor): Pair<FlowContinuation, StateMachineState> {
+        val metricActionInterceptor = MetricActionInterceptor(metrics, actionExecutor)
+        return delegate.executeTransition(fiber, previousState, event, transition, metricActionInterceptor)
+    }
+}
+
+class MetricActionInterceptor(val metrics: MetricRegistry, val delegate: ActionExecutor): ActionExecutor {
+    @Suspendable
+    override fun executeAction(fiber: FlowFiber, action: Action) {
+        val context = metrics.timer("Flows.Actions.${action.javaClass.simpleName}").time()
+        delegate.executeAction(fiber, action)
+        context.stop()
+    }
+}
\ No newline at end of file