Made MaintenanceSchedulerImpl constructor private to prevent having multiple instances

2 files changed, 12 insertions, 2 deletions

diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/MaintenanceSchedulerImpl.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/MaintenanceSchedulerImpl.java
index 5e9b89c9ca9..4345b591a0b 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/MaintenanceSchedulerImpl.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/MaintenanceSchedulerImpl.java
@@ -32,7 +32,16 @@ public class MaintenanceSchedulerImpl extends AbstractComponent implements Runna
     private final ScheduledExecutorService service = new ScheduledThreadPoolExecutor(1);
     private Queue<String> jobQueue = new LinkedBlockingQueue<>();
 
-    public MaintenanceSchedulerImpl() {
+    private static MaintenanceScheduler maintenanceScheduler = null;
+
+    // Because of the regular job queue, we must have only one instance of this class
+    public static MaintenanceScheduler getInstance() {
+        if (maintenanceScheduler == null) maintenanceScheduler = new MaintenanceSchedulerImpl();
+
+        return maintenanceScheduler;
+    }
+
+    private MaintenanceSchedulerImpl() {
         service.scheduleAtFixedRate(this, rate.toMillis(), rate.toMillis(), TimeUnit.MILLISECONDS);
 
         addRegularJob(Maintainer.JOB_DELETE_OLD_APP_DATA,
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/provider/ComponentsProviderImpl.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/provider/ComponentsProviderImpl.java
index 2adee07b5b0..b7f8710e85e 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/provider/ComponentsProviderImpl.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/provider/ComponentsProviderImpl.java
@@ -2,6 +2,7 @@
 package com.yahoo.vespa.hosted.node.admin.provider;
 
 import com.yahoo.vespa.applicationmodel.HostName;
+import com.yahoo.vespa.hosted.node.admin.maintenance.MaintenanceScheduler;
 import com.yahoo.vespa.hosted.node.admin.maintenance.MaintenanceSchedulerImpl;
 import com.yahoo.vespa.hosted.node.admin.nodeadmin.NodeAdmin;
 import com.yahoo.vespa.hosted.node.admin.nodeadmin.NodeAdminImpl;
@@ -48,7 +49,7 @@ public class ComponentsProviderImpl implements ComponentsProvider {
 
         NodeRepository nodeRepository = new NodeRepositoryImpl(configServerHosts, HARDCODED_NODEREPOSITORY_PORT, baseHostName);
         Orchestrator orchestrator = OrchestratorImpl.createOrchestratorFromSettings();
-        MaintenanceSchedulerImpl maintenanceScheduler = new MaintenanceSchedulerImpl();
+        MaintenanceScheduler maintenanceScheduler = MaintenanceSchedulerImpl.getInstance();
 
         final Function<HostName, NodeAgent> nodeAgentFactory = (hostName) ->
                 new NodeAgentImpl(hostName, nodeRepository, orchestrator, new DockerOperations(docker), maintenanceScheduler);