Merge pull request #12500 from vespa-engine/hakonhall/avoid-building-lots-of-applicationinstances

Avoid building lots of ApplicationInstances

12 files changed, 159 insertions, 97 deletions

diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/application/OrchestratorMock.java b/configserver/src/test/java/com/yahoo/vespa/config/server/application/OrchestratorMock.java
index 837cbd4605a..88d486cef87 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/application/OrchestratorMock.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/application/OrchestratorMock.java
@@ -2,6 +2,7 @@
 package com.yahoo.vespa.config.server.application;
 
 import com.yahoo.config.provision.ApplicationId;
+import com.yahoo.vespa.applicationmodel.ApplicationInstanceReference;
 import com.yahoo.vespa.applicationmodel.HostName;
 import com.yahoo.vespa.orchestrator.Host;
 import com.yahoo.vespa.orchestrator.Orchestrator;
@@ -41,6 +42,12 @@ public class OrchestratorMock implements Orchestrator {
     }
 
     @Override
+    public HostInfo getHostInfo(ApplicationInstanceReference reference, HostName hostname) {
+        HostInfo hostInfo = hostInfos.get(hostname);
+        return hostInfo == null ? HostInfo.createNoRemarks() : hostInfo;
+    }
+
+    @Override
     public Function<HostName, Optional<HostInfo>> getHostResolver() {
         return hostName -> Optional.of(hostInfos.getOrDefault(hostName, HostInfo.createNoRemarks()));
     }
diff --git a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/MetricsReporter.java b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/MetricsReporter.java
index e65b7273b9e..e107abf8fbb 100644
--- a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/MetricsReporter.java
+++ b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/MetricsReporter.java
@@ -6,6 +6,7 @@ import com.yahoo.config.provision.ApplicationId;
 import com.yahoo.config.provision.NodeResources;
 import com.yahoo.config.provision.NodeType;
 import com.yahoo.jdisc.Metric;
+import com.yahoo.vespa.applicationmodel.ApplicationInstance;
 import com.yahoo.vespa.applicationmodel.HostName;
 import com.yahoo.vespa.applicationmodel.ServiceInstance;
 import com.yahoo.vespa.applicationmodel.ServiceStatus;
@@ -15,7 +16,7 @@ import com.yahoo.vespa.hosted.provision.NodeRepository;
 import com.yahoo.vespa.hosted.provision.node.Allocation;
 import com.yahoo.vespa.hosted.provision.node.History;
 import com.yahoo.vespa.orchestrator.Orchestrator;
-import com.yahoo.vespa.orchestrator.status.HostInfo;
+import com.yahoo.vespa.service.monitor.ServiceModel;
 import com.yahoo.vespa.service.monitor.ServiceMonitor;
 
 import java.time.Clock;
@@ -24,7 +25,6 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.function.Function;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
 
@@ -36,7 +36,7 @@ import static com.yahoo.config.provision.NodeResources.DiskSpeed.any;
 public class MetricsReporter extends Maintainer {
 
     private final Metric metric;
-    private final Function<HostName, Optional<HostInfo>> orchestrator;
+    private final Orchestrator orchestrator;
     private final ServiceMonitor serviceMonitor;
     private final Map<Map<String, String>, Metric.Context> contextMap = new HashMap<>();
     private final Supplier<Integer> pendingRedeploymentsSupplier;
@@ -51,7 +51,7 @@ public class MetricsReporter extends Maintainer {
                     Clock clock) {
         super(nodeRepository, interval);
         this.metric = metric;
-        this.orchestrator = orchestrator.getHostResolver();
+        this.orchestrator = orchestrator;
         this.serviceMonitor = serviceMonitor;
         this.pendingRedeploymentsSupplier = pendingRedeploymentsSupplier;
         this.clock = clock;
@@ -60,9 +60,9 @@ public class MetricsReporter extends Maintainer {
     @Override
     public void maintain() {
         NodeList nodes = nodeRepository().list();
-        Map<HostName, List<ServiceInstance>> servicesByHost = serviceMonitor.getServicesByHostname();
+        ServiceModel serviceModel = serviceMonitor.getServiceModelSnapshot();
 
-        nodes.forEach(node -> updateNodeMetrics(node, servicesByHost));
+        nodes.forEach(node -> updateNodeMetrics(node, serviceModel));
         updateStateMetrics(nodes);
         updateMaintenanceMetrics();
         updateDockerMetrics(nodes);
@@ -73,7 +73,7 @@ public class MetricsReporter extends Maintainer {
         metric.set("hostedVespa.pendingRedeployments", pendingRedeploymentsSupplier.get(), null);
     }
 
-    private void updateNodeMetrics(Node node, Map<HostName, List<ServiceInstance>> servicesByHost) {
+    private void updateNodeMetrics(Node node, ServiceModel serviceModel) {
         Metric.Context context;
 
         Optional<Allocation> allocation = node.allocation();
@@ -128,19 +128,23 @@ public class MetricsReporter extends Maintainer {
         metric.set("wantToDeprovision", node.status().wantToDeprovision() ? 1 : 0, context);
         metric.set("failReport", NodeFailer.reasonsToFailParentHost(node).isEmpty() ? 0 : 1, context);
 
-        orchestrator.apply(new HostName(node.hostname())).ifPresent(info -> {
-            int suspended = info.status().isSuspended() ? 1 : 0;
-            metric.set("suspended", suspended, context);
-            metric.set("allowedToBeDown", suspended, context); // remove summer 2020.
-            long suspendedSeconds = info.suspendedSince()
-                    .map(suspendedSince -> Duration.between(suspendedSince, clock.instant()).getSeconds())
-                    .orElse(0L);
-            metric.set("suspendedSeconds", suspendedSeconds, context);
-        });
+        HostName hostname = new HostName(node.hostname());
+
+        serviceModel.getApplication(hostname)
+                .map(ApplicationInstance::reference)
+                .map(reference -> orchestrator.getHostInfo(reference, hostname))
+                .ifPresent(info -> {
+                    int suspended = info.status().isSuspended() ? 1 : 0;
+                    metric.set("suspended", suspended, context);
+                    metric.set("allowedToBeDown", suspended, context); // remove summer 2020.
+                    long suspendedSeconds = info.suspendedSince()
+                            .map(suspendedSince -> Duration.between(suspendedSince, clock.instant()).getSeconds())
+                            .orElse(0L);
+                    metric.set("suspendedSeconds", suspendedSeconds, context);
+                });
 
         long numberOfServices;
-        HostName hostName = new HostName(node.hostname());
-        List<ServiceInstance> services = servicesByHost.get(hostName);
+        List<ServiceInstance> services = serviceModel.getServiceInstancesByHostName().get(hostname);
         if (services == null) {
             numberOfServices = 0;
         } else {
diff --git a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/NodeFailer.java b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/NodeFailer.java
index 8a5a119f6a7..b0b8f7d8d2c 100644
--- a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/NodeFailer.java
+++ b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/NodeFailer.java
@@ -186,7 +186,7 @@ public class NodeFailer extends Maintainer {
         Map<String, Node> activeNodesByHostname = nodeRepository().getNodes(Node.State.active).stream()
                 .collect(Collectors.toMap(Node::hostname, node -> node));
 
-        serviceMonitor.getServicesByHostname()
+        serviceMonitor.getServiceModelSnapshot().getServiceInstancesByHostName()
                 .forEach((hostName, serviceInstances) -> {
                     Node node = activeNodesByHostname.get(hostName.s());
                     if (node == null) return;
diff --git a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/NodeRepositoryMaintenance.java b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/NodeRepositoryMaintenance.java
index ecc550527fc..c3c488c9616 100644
--- a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/NodeRepositoryMaintenance.java
+++ b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/maintenance/NodeRepositoryMaintenance.java
@@ -8,10 +8,10 @@ import com.yahoo.config.provision.Environment;
 import com.yahoo.config.provision.HostLivenessTracker;
 import com.yahoo.config.provision.InfraDeployer;
 import com.yahoo.config.provision.Zone;
-import com.yahoo.vespa.hosted.provision.autoscale.NodeMetrics;
 import com.yahoo.jdisc.Metric;
 import com.yahoo.vespa.flags.FlagSource;
 import com.yahoo.vespa.hosted.provision.NodeRepository;
+import com.yahoo.vespa.hosted.provision.autoscale.NodeMetrics;
 import com.yahoo.vespa.hosted.provision.autoscale.NodeMetricsDb;
 import com.yahoo.vespa.hosted.provision.provisioning.ProvisionServiceProvider;
 import com.yahoo.vespa.orchestrator.Orchestrator;
diff --git a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/testutils/OrchestratorMock.java b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/testutils/OrchestratorMock.java
index d183e62c96c..ff9cb98783c 100644
--- a/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/testutils/OrchestratorMock.java
+++ b/node-repository/src/main/java/com/yahoo/vespa/hosted/provision/testutils/OrchestratorMock.java
@@ -3,6 +3,7 @@ package com.yahoo.vespa.hosted.provision.testutils;
 
 import com.yahoo.component.AbstractComponent;
 import com.yahoo.config.provision.ApplicationId;
+import com.yahoo.vespa.applicationmodel.ApplicationInstanceReference;
 import com.yahoo.vespa.applicationmodel.HostName;
 import com.yahoo.vespa.orchestrator.Host;
 import com.yahoo.vespa.orchestrator.Orchestrator;
@@ -40,6 +41,12 @@ public class OrchestratorMock extends AbstractComponent implements Orchestrator
     }
 
     @Override
+    public HostInfo getHostInfo(ApplicationInstanceReference reference, HostName hostname) {
+        HostInfo hostInfo = suspendedHosts.get(hostname);
+        return hostInfo == null ? HostInfo.createNoRemarks() : hostInfo;
+    }
+
+    @Override
     public Function<HostName, Optional<HostInfo>> getHostResolver() {
         return hostName -> Optional.of(suspendedHosts.getOrDefault(hostName, HostInfo.createNoRemarks()));
     }
diff --git a/node-repository/src/test/java/com/yahoo/vespa/hosted/provision/maintenance/MetricsReporterTest.java b/node-repository/src/test/java/com/yahoo/vespa/hosted/provision/maintenance/MetricsReporterTest.java
index 8daec1d641e..ddca903a5c2 100644
--- a/node-repository/src/test/java/com/yahoo/vespa/hosted/provision/maintenance/MetricsReporterTest.java
+++ b/node-repository/src/test/java/com/yahoo/vespa/hosted/provision/maintenance/MetricsReporterTest.java
@@ -11,6 +11,8 @@ import com.yahoo.config.provision.NodeType;
 import com.yahoo.config.provision.Zone;
 import com.yahoo.jdisc.Metric;
 import com.yahoo.test.ManualClock;
+import com.yahoo.vespa.applicationmodel.ApplicationInstance;
+import com.yahoo.vespa.applicationmodel.ApplicationInstanceReference;
 import com.yahoo.vespa.curator.Curator;
 import com.yahoo.vespa.curator.mock.MockCurator;
 import com.yahoo.vespa.flags.InMemoryFlagSource;
@@ -26,7 +28,9 @@ import com.yahoo.vespa.hosted.provision.testutils.MockNameResolver;
 import com.yahoo.vespa.orchestrator.Orchestrator;
 import com.yahoo.vespa.orchestrator.status.HostInfo;
 import com.yahoo.vespa.orchestrator.status.HostStatus;
+import com.yahoo.vespa.service.monitor.ServiceModel;
 import com.yahoo.vespa.service.monitor.ServiceMonitor;
+import org.junit.Before;
 import org.junit.Test;
 
 import java.time.Clock;
@@ -40,6 +44,8 @@ import java.util.Optional;
 import java.util.Set;
 
 import static org.junit.Assert.assertEquals;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
@@ -48,6 +54,23 @@ import static org.mockito.Mockito.when;
  * @author smorgrav
  */
 public class MetricsReporterTest {
+    private final ServiceMonitor serviceMonitor = mock(ServiceMonitor.class);
+    private final ApplicationInstanceReference reference = mock(ApplicationInstanceReference.class);
+
+    @Before
+    public void setUp() {
+        // On the serviceModel returned by serviceMonitor.getServiceModelSnapshot(),
+        // 2 methods should be used by MetricsReporter:
+        //  - getServiceInstancesByHostName() -> empty Map
+        //  - getApplication() which is mapped to a dummy ApplicationInstanceReference and
+        //    used for lookup.
+        ServiceModel serviceModel = mock(ServiceModel.class);
+        when(serviceMonitor.getServiceModelSnapshot()).thenReturn(serviceModel);
+        when(serviceModel.getServiceInstancesByHostName()).thenReturn(Map.of());
+        ApplicationInstance applicationInstance = mock(ApplicationInstance.class);
+        when(serviceModel.getApplication(any())).thenReturn(Optional.of(applicationInstance));
+        when(applicationInstance.reference()).thenReturn(reference);
+    }
 
     @Test
     public void test_registered_metric() {
@@ -91,12 +114,10 @@ public class MetricsReporterTest {
         expectedMetrics.put("numberOfServices", 0L);
 
         ManualClock clock = new ManualClock(Instant.ofEpochSecond(124));
+
         Orchestrator orchestrator = mock(Orchestrator.class);
-        ServiceMonitor serviceMonitor = mock(ServiceMonitor.class);
-        when(orchestrator.getHostResolver()).thenReturn(hostName ->
-            Optional.of(HostInfo.createSuspended(HostStatus.ALLOWED_TO_BE_DOWN, Instant.ofEpochSecond(1)))
-        );
-        when(serviceMonitor.getServicesByHostname()).thenReturn(Map.of());
+        when(orchestrator.getHostInfo(eq(reference), any())).thenReturn(
+                HostInfo.createSuspended(HostStatus.ALLOWED_TO_BE_DOWN, Instant.ofEpochSecond(1)));
 
         TestMetric metric = new TestMetric();
         MetricsReporter metricsReporter = new MetricsReporter(
@@ -141,9 +162,7 @@ public class MetricsReporterTest {
         nodeRepository.addDockerNodes(new LockedNodeList(List.of(container2), nodeRepository.lockUnallocated()));
 
         Orchestrator orchestrator = mock(Orchestrator.class);
-        ServiceMonitor serviceMonitor = mock(ServiceMonitor.class);
-        when(orchestrator.getHostResolver()).thenReturn(hostName -> Optional.of(HostInfo.createNoRemarks()));
-        when(serviceMonitor.getServicesByHostname()).thenReturn(Map.of());
+        when(orchestrator.getHostInfo(eq(reference), any())).thenReturn(HostInfo.createNoRemarks());
 
         TestMetric metric = new TestMetric();
         ManualClock clock = new ManualClock();
diff --git a/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/Orchestrator.java b/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/Orchestrator.java
index 10fa10f1150..9d2d72277e5 100644
--- a/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/Orchestrator.java
+++ b/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/Orchestrator.java
@@ -2,8 +2,8 @@
 package com.yahoo.vespa.orchestrator;
 
 import com.yahoo.config.provision.ApplicationId;
+import com.yahoo.vespa.applicationmodel.ApplicationInstanceReference;
 import com.yahoo.vespa.applicationmodel.HostName;
-import com.yahoo.vespa.orchestrator.model.NodeGroup;
 import com.yahoo.vespa.orchestrator.policy.BatchHostStateChangeDeniedException;
 import com.yahoo.vespa.orchestrator.policy.HostStateChangeDeniedException;
 import com.yahoo.vespa.orchestrator.status.ApplicationInstanceStatus;
@@ -45,10 +45,13 @@ public interface Orchestrator {
      *
      * @param hostName The FQDN which are used in the noderepo.
      * @return The enum describing the current state.
-     * @throws HostNameNotFoundException if hostName is unrecognized (in node repo)
+     * @throws HostNameNotFoundException if hostName is not associated with any application
      */
     HostStatus getNodeStatus(HostName hostName) throws HostNameNotFoundException;
 
+    /** Get host info for hostname in application, returning no-remarks if not in application. */
+    HostInfo getHostInfo(ApplicationInstanceReference reference, HostName hostname);
+
     /**
      * Returns a lambda, which when invoked with a hostname, returns its current host info.
      *
diff --git a/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/OrchestratorImpl.java b/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/OrchestratorImpl.java
index 5ac5c66cc7c..f36f7088424 100644
--- a/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/OrchestratorImpl.java
+++ b/orchestrator/src/main/java/com/yahoo/vespa/orchestrator/OrchestratorImpl.java
@@ -127,19 +127,25 @@ public class OrchestratorImpl implements Orchestrator {
 
     @Override
     public HostStatus getNodeStatus(HostName hostName) throws HostNameNotFoundException {
-        return getNodeStatus(getApplicationInstance(hostName).reference(), hostName);
+        ApplicationInstanceReference reference = getApplicationInstanceReference(hostName);
+        return statusService.getHostInfo(reference, hostName).status();
+    }
+
+    @Override
+    public HostInfo getHostInfo(ApplicationInstanceReference reference, HostName hostname) {
+        return statusService.getHostInfo(reference, hostname);
     }
 
     @Override
     public Function<HostName, Optional<HostInfo>> getHostResolver() {
         return hostName -> serviceMonitor
-                .getApplication(hostName)
-                .map(application -> statusService.getHostInfo(application.reference(), hostName));
+                .getApplicationInstanceReference(hostName)
+                .map(reference -> statusService.getHostInfo(reference, hostName));
     }
 
     @Override
     public void setNodeStatus(HostName hostName, HostStatus status) throws OrchestrationException {
-        ApplicationInstanceReference reference = getApplicationInstance(hostName).reference();
+        ApplicationInstanceReference reference = getApplicationInstanceReference(hostName);
         OrchestratorContext context = OrchestratorContext.createContextForSingleAppOp(clock);
         try (ApplicationLock lock = statusService.lockApplication(context, reference)) {
             lock.setHostState(hostName, status);
@@ -347,11 +353,7 @@ public class OrchestratorImpl implements Orchestrator {
         return leftApplicationReference.asString().compareTo(rightApplicationReference.asString());
     }
 
-    private HostStatus getNodeStatus(ApplicationInstanceReference applicationRef, HostName hostName) {
-        return statusService.getHostInfo(applicationRef, hostName).status();
-    }
-
-    private void setApplicationStatus(ApplicationId appId, ApplicationInstanceStatus status) 
+    private void setApplicationStatus(ApplicationId appId, ApplicationInstanceStatus status)
             throws ApplicationStateChangeDeniedException, ApplicationIdNotFoundException{
         OrchestratorContext context = OrchestratorContext.createContextForSingleAppOp(clock);
         ApplicationInstanceReference reference = OrchestratorUtil.toApplicationInstanceReference(appId, serviceMonitor);
@@ -420,9 +422,14 @@ public class OrchestratorImpl implements Orchestrator {
         }
     }
 
+    private ApplicationInstanceReference getApplicationInstanceReference(HostName hostname) throws HostNameNotFoundException {
+        return serviceMonitor.getApplicationInstanceReference(hostname)
+                .orElseThrow(() -> new HostNameNotFoundException(hostname));
+    }
+
     private ApplicationInstance getApplicationInstance(HostName hostName) throws HostNameNotFoundException{
-        return serviceMonitor.getApplication(hostName).orElseThrow(
-                () -> new HostNameNotFoundException(hostName));
+        return serviceMonitor.getApplication(hostName)
+                .orElseThrow(() -> new HostNameNotFoundException(hostName));
     }
 
     private static void sleep(long time, TimeUnit timeUnit) {
diff --git a/orchestrator/src/test/java/com/yahoo/vespa/orchestrator/DummyServiceMonitor.java b/orchestrator/src/test/java/com/yahoo/vespa/orchestrator/DummyServiceMonitor.java
index a784187fb62..501a09f78ff 100644
--- a/orchestrator/src/test/java/com/yahoo/vespa/orchestrator/DummyServiceMonitor.java
+++ b/orchestrator/src/test/java/com/yahoo/vespa/orchestrator/DummyServiceMonitor.java
@@ -163,11 +163,6 @@ public class DummyServiceMonitor implements ServiceMonitor, AntiServiceMonitor {
     }
 
     @Override
-    public Map<HostName, List<ServiceInstance>> getServicesByHostname() {
-        throw new UnsupportedOperationException();
-    }
-
-    @Override
     public CriticalRegion disallowDuperModelLockAcquisition(String regionDescription) {
         return () -> {};
     }
diff --git a/service-monitor/src/main/java/com/yahoo/vespa/service/model/ServiceMonitorImpl.java b/service-monitor/src/main/java/com/yahoo/vespa/service/model/ServiceMonitorImpl.java
index 678b0d3d5ba..e6e6e85c710 100644
--- a/service-monitor/src/main/java/com/yahoo/vespa/service/model/ServiceMonitorImpl.java
+++ b/service-monitor/src/main/java/com/yahoo/vespa/service/model/ServiceMonitorImpl.java
@@ -10,7 +10,6 @@ import com.yahoo.jdisc.Timer;
 import com.yahoo.vespa.applicationmodel.ApplicationInstance;
 import com.yahoo.vespa.applicationmodel.ApplicationInstanceReference;
 import com.yahoo.vespa.applicationmodel.HostName;
-import com.yahoo.vespa.applicationmodel.ServiceInstance;
 import com.yahoo.vespa.service.duper.DuperModelManager;
 import com.yahoo.vespa.service.manager.MonitorManager;
 import com.yahoo.vespa.service.manager.UnionMonitorManager;
@@ -21,8 +20,6 @@ import com.yahoo.vespa.service.monitor.ServiceModel;
 import com.yahoo.vespa.service.monitor.ServiceMonitor;
 import com.yahoo.vespa.service.monitor.ServiceStatusProvider;
 
-import java.util.List;
-import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 
@@ -70,13 +67,16 @@ public class ServiceMonitorImpl implements ServiceMonitor, AntiServiceMonitor {
     }
 
     @Override
-    public Optional<ApplicationInstance> getApplication(HostName hostname) {
-        Optional<ApplicationInfo> applicationInfo = getApplicationInfo(hostname);
-        if (applicationInfo.isEmpty()) {
-            return Optional.empty();
-        }
+    public Optional<ApplicationInstanceReference> getApplicationInstanceReference(HostName hostname) {
+        return duperModelManager.getApplicationInfo(toConfigProvisionHostName(hostname))
+                .map(ApplicationInfo::getApplicationId)
+                .map(modelGenerator::toApplicationInstanceReference);
+    }
 
-        return Optional.of(modelGenerator.toApplicationInstance(applicationInfo.get(), serviceStatusProvider));
+    @Override
+    public Optional<ApplicationInstance> getApplication(HostName hostname) {
+        return getApplicationInfo(hostname)
+                .map(applicationInfo -> modelGenerator.toApplicationInstance(applicationInfo, serviceStatusProvider));
     }
 
     @Override
@@ -97,11 +97,6 @@ public class ServiceMonitorImpl implements ServiceMonitor, AntiServiceMonitor {
     }
 
     @Override
-    public Map<HostName, List<ServiceInstance>> getServicesByHostname() {
-        return getServiceModelSnapshot().getServiceInstancesByHostName();
-    }
-
-    @Override
     public void registerListener(ServiceHostListener listener) {
         var duperModelListener = ServiceHostListenerAdapter.asDuperModelListener(listener, modelGenerator);
         duperModelManager.registerListener(duperModelListener);
@@ -118,8 +113,11 @@ public class ServiceMonitorImpl implements ServiceMonitor, AntiServiceMonitor {
     }
 
     private Optional<ApplicationInfo> getApplicationInfo(HostName hostname) {
-        // The duper model uses HostName from config.provision, which is more natural than applicationmodel.
-        var configProvisionHostname = com.yahoo.config.provision.HostName.from(hostname.s());
-        return duperModelManager.getApplicationInfo(configProvisionHostname);
+        return duperModelManager.getApplicationInfo(toConfigProvisionHostName(hostname));
+    }
+
+    /** The duper model uses HostName from config.provision. */
+    private static com.yahoo.config.provision.HostName toConfigProvisionHostName(HostName hostname) {
+        return com.yahoo.config.provision.HostName.from(hostname.s());
     }
 }
diff --git a/service-monitor/src/main/java/com/yahoo/vespa/service/monitor/ServiceModel.java b/service-monitor/src/main/java/com/yahoo/vespa/service/monitor/ServiceModel.java
index ed72893400a..c8f491a0fc7 100644
--- a/service-monitor/src/main/java/com/yahoo/vespa/service/monitor/ServiceModel.java
+++ b/service-monitor/src/main/java/com/yahoo/vespa/service/monitor/ServiceModel.java
@@ -1,66 +1,91 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.service.monitor;
 
+import com.yahoo.config.model.api.ApplicationInfo;
 import com.yahoo.vespa.applicationmodel.ApplicationInstance;
 import com.yahoo.vespa.applicationmodel.ApplicationInstanceReference;
 import com.yahoo.vespa.applicationmodel.HostName;
 import com.yahoo.vespa.applicationmodel.ServiceCluster;
 import com.yahoo.vespa.applicationmodel.ServiceInstance;
 
+import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.stream.Collectors;
 
 /**
- * The ServiceModel is almost a mirror of the SuperModel, except that it
- * also gives ServiceStatus on each service, and there may be
- * artificial applications like the config server "application".
+ * The service model is the union of the duper model and the service monitor, and presented
+ * as classes from the {@code application-model} module.
+ *
+ * <p>The duper model contains the latest {@link ApplicationInfo} of both tenant and infrastructure
+ * applications. The service monitor provides Slobrok or {@code /state/v1/health} information
+ * on (most) services. The application model presents an application as a set of clusters, and
+ * each cluster a set of services, and each service is associated with a particular host
+ * and has a health status.</p>
+ *
+ * @author hakonhall
  */
 public class ServiceModel {
 
-    private final Map<ApplicationInstanceReference, ApplicationInstance> applications;
-    private final Map<HostName, ApplicationInstance> applicationsByHostName;
+    private final Map<ApplicationInstanceReference, ApplicationInstance> applicationsByReference;
 
-    public ServiceModel(Map<ApplicationInstanceReference, ApplicationInstance> applications) {
-        this.applications = Collections.unmodifiableMap(applications);
-        this.applicationsByHostName = Collections.unmodifiableMap(applicationsByHostNames(applications.values()));
+    private Map<HostName, ApplicationInstance> applicationsByHostName = null;
+    private Map<HostName, List<ServiceInstance>> servicesByHostName = null;
+
+    public ServiceModel(Map<ApplicationInstanceReference, ApplicationInstance> applicationsByReference) {
+        this.applicationsByReference = Collections.unmodifiableMap(Map.copyOf(applicationsByReference));
     }
 
     public Map<ApplicationInstanceReference, ApplicationInstance> getAllApplicationInstances() {
-        return applications;
+        return applicationsByReference;
     }
 
     public Optional<ApplicationInstance> getApplicationInstance(ApplicationInstanceReference reference) {
-        return Optional.ofNullable(applications.get(reference));
+        return Optional.ofNullable(applicationsByReference.get(reference));
     }
 
-    public Map<HostName, ApplicationInstance> getApplicationsByHostName() {
-        return applicationsByHostName;
+    public Optional<ApplicationInstance> getApplication(HostName hostname) {
+        if (applicationsByHostName == null) {
+            fillMaps();
+        }
+
+        return Optional.ofNullable(applicationsByHostName.get(hostname));
     }
 
     public Map<HostName, List<ServiceInstance>> getServiceInstancesByHostName() {
-        return applications.values().stream()
-                .flatMap(application -> application.serviceClusters().stream())
-                .flatMap(cluster -> cluster.serviceInstances().stream())
-                .collect(Collectors.groupingBy(ServiceInstance::hostName, Collectors.toList()));
+        if (servicesByHostName == null) {
+            fillMaps();
+        }
+
+        return servicesByHostName;
     }
 
-    private static Map<HostName, ApplicationInstance> applicationsByHostNames(Collection<ApplicationInstance> applications) {
-        Map<HostName, ApplicationInstance> hosts = new HashMap<>();
-        for (ApplicationInstance application : applications)
-            for (ServiceCluster cluster : application.serviceClusters())
+    private void fillMaps() {
+        Map<HostName, ApplicationInstance> applicationInstances = new HashMap<>();
+        Map<HostName, List<ServiceInstance>> serviceInstances = new HashMap<>();
+
+        for (ApplicationInstance application : applicationsByReference.values()) {
+            for (ServiceCluster cluster : application.serviceClusters()) {
                 for (ServiceInstance instance : cluster.serviceInstances()) {
-                    ApplicationInstance previous = hosts.put(instance.hostName(), application);
-                    if (previous != null && ! previous.equals(application))
+
+                    ApplicationInstance previous = applicationInstances.put(instance.hostName(), application);
+                    if (previous != null && !previous.equals(application)) {
                         throw new IllegalStateException("Major assumption broken: Multiple application instances contain host " +
-                                                        instance.hostName().s() + ": " + Arrays.asList(previous, application));
+                                instance.hostName().s() + ": " + Arrays.asList(previous, application));
+                    }
+
+                    serviceInstances
+                            .computeIfAbsent(instance.hostName(), key -> new ArrayList<>())
+                            .add(instance);
                 }
-        return hosts;
+            }
+        }
+
+        applicationsByHostName = Collections.unmodifiableMap(applicationInstances);
+        servicesByHostName = Collections.unmodifiableMap(serviceInstances);
     }
 
 }
diff --git a/service-monitor/src/main/java/com/yahoo/vespa/service/monitor/ServiceMonitor.java b/service-monitor/src/main/java/com/yahoo/vespa/service/monitor/ServiceMonitor.java
index 0d162fee182..4f52d7d229c 100644
--- a/service-monitor/src/main/java/com/yahoo/vespa/service/monitor/ServiceMonitor.java
+++ b/service-monitor/src/main/java/com/yahoo/vespa/service/monitor/ServiceMonitor.java
@@ -4,10 +4,7 @@ package com.yahoo.vespa.service.monitor;
 import com.yahoo.vespa.applicationmodel.ApplicationInstance;
 import com.yahoo.vespa.applicationmodel.ApplicationInstanceReference;
 import com.yahoo.vespa.applicationmodel.HostName;
-import com.yahoo.vespa.applicationmodel.ServiceInstance;
 
-import java.util.List;
-import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 
@@ -31,8 +28,12 @@ public interface ServiceMonitor {
         return getServiceModelSnapshot().getAllApplicationInstances().keySet();
     }
 
+    default Optional<ApplicationInstanceReference> getApplicationInstanceReference(HostName hostname) {
+        return getApplication(hostname).map(ApplicationInstance::reference);
+    }
+
     default Optional<ApplicationInstance> getApplication(HostName hostname) {
-        return Optional.ofNullable(getServiceModelSnapshot().getApplicationsByHostName().get(hostname));
+        return getServiceModelSnapshot().getApplication(hostname);
     }
 
     default Optional<ApplicationInstance> getApplication(ApplicationInstanceReference reference) {
@@ -43,10 +44,6 @@ public interface ServiceMonitor {
         return getApplication(hostname);
     }
 
-    default Map<HostName, List<ServiceInstance>> getServicesByHostname() {
-        return getServiceModelSnapshot().getServiceInstancesByHostName();
-    }
-
     /**
      * Get notified of changes to the set of applications, or set of hosts assigned to an application.
      *