Use singletons for all fallback components

2 files changed, 10 insertions, 3 deletions

diff --git a/container-core/src/main/java/com/yahoo/container/core/config/HandlersConfigurerDi.java b/container-core/src/main/java/com/yahoo/container/core/config/HandlersConfigurerDi.java
index 0fd31db67f6..05f34a27bc9 100644
--- a/container-core/src/main/java/com/yahoo/container/core/config/HandlersConfigurerDi.java
+++ b/container-core/src/main/java/com/yahoo/container/core/config/HandlersConfigurerDi.java
@@ -48,6 +48,9 @@ public class HandlersConfigurerDi {
 
     private static final Logger log = Logger.getLogger(HandlersConfigurerDi.class.getName());
 
+    private static final Executor fallbackExecutor = Executors.newCachedThreadPool(
+            ThreadFactoryFactory.getThreadFactory("HandlersConfigurerDI"));
+
     private final com.yahoo.container.Container vespaContainer;
     private final Container container;
 
@@ -138,10 +141,12 @@ public class HandlersConfigurerDi {
         return discInjector.createChildInjector(new AbstractModule() {
             @Override
             protected void configure() {
+                // Provide a singleton instance for all component fallbacks,
+                // otherwise fallback injection may lead to a cascade of components requiring reconstruction.
                 bind(com.yahoo.container.Container.class).toInstance(vespaContainer);
                 bind(com.yahoo.statistics.Statistics.class).toInstance(Statistics.nullImplementation);
-                bind(AccessLog.class).toInstance(new AccessLog(new ComponentRegistry<>()));
-                bind(Executor.class).toInstance(Executors.newCachedThreadPool(ThreadFactoryFactory.getThreadFactory("HandlersConfigurerDI")));
+                bind(AccessLog.class).toInstance(AccessLog.VOID_INSTANCE);
+                bind(Executor.class).toInstance(fallbackExecutor);
                 if (vespaContainer.getFileAcquirer() != null)
                     bind(com.yahoo.filedistribution.fileacquirer.FileAcquirer.class).toInstance(vespaContainer.getFileAcquirer());
             }
diff --git a/jdisc_http_service/src/main/java/com/yahoo/container/logging/AccessLog.java b/jdisc_http_service/src/main/java/com/yahoo/container/logging/AccessLog.java
index cdb4febb775..1db5d9b82f1 100644
--- a/jdisc_http_service/src/main/java/com/yahoo/container/logging/AccessLog.java
+++ b/jdisc_http_service/src/main/java/com/yahoo/container/logging/AccessLog.java
@@ -13,6 +13,8 @@ import com.yahoo.component.provider.ComponentRegistry;
  */
 public class AccessLog implements RequestLog {
 
+    public static final AccessLog VOID_INSTANCE = new AccessLog(new ComponentRegistry<>());
+
     private final ComponentRegistry<RequestLogHandler> implementers;
 
     @Inject
@@ -21,7 +23,7 @@ public class AccessLog implements RequestLog {
     }
 
     public static AccessLog voidAccessLog() {
-        return new AccessLog(new ComponentRegistry<>());
+        return VOID_INSTANCE;
     }
 
     @Override