Use a bound queue for rendering tasks

If we add rendering tasks faster than we are able to complete them
we may run out of memory, so bound the queue.

2 files changed, 40 insertions, 10 deletions

diff --git a/container-search/src/main/java/com/yahoo/search/searchchain/ExecutionFactory.java b/container-search/src/main/java/com/yahoo/search/searchchain/ExecutionFactory.java
index 87880ce2445..dc044c77c94 100644
--- a/container-search/src/main/java/com/yahoo/search/searchchain/ExecutionFactory.java
+++ b/container-search/src/main/java/com/yahoo/search/searchchain/ExecutionFactory.java
@@ -86,7 +86,7 @@ public class ExecutionFactory extends AbstractComponent {
         this.schemaInfo = schemaInfo;
         this.specialTokens = new SpecialTokenRegistry(specialTokens);
         this.linguistics = linguistics;
-        this.renderingExecutor = createRenderingExecutor();
+        this.renderingExecutor = new RenderingExecutorFactory().createExecutor();
         this.rendererRegistry = new RendererRegistry(renderers.allComponents(), renderingExecutor);
         this.executor = executor != null ? executor : Executors.newSingleThreadExecutor();
     }
@@ -151,13 +151,4 @@ public class ExecutionFactory extends AbstractComponent {
                                     null);
     }
 
-    private static ThreadPoolExecutor createRenderingExecutor() {
-        int threadCount = Runtime.getRuntime().availableProcessors();
-        ThreadPoolExecutor executor = new ThreadPoolExecutor(threadCount, threadCount, 1L, TimeUnit.SECONDS,
-                                                             new LinkedBlockingQueue<>(),
-                                                             ThreadFactoryFactory.getThreadFactory("common-rendering"));
-        executor.prestartAllCoreThreads();
-        return executor;
-    }
-
 }
diff --git a/container-search/src/main/java/com/yahoo/search/searchchain/RenderingExecutorFactory.java b/container-search/src/main/java/com/yahoo/search/searchchain/RenderingExecutorFactory.java
new file mode 100644
index 00000000000..f67db059470
--- /dev/null
+++ b/container-search/src/main/java/com/yahoo/search/searchchain/RenderingExecutorFactory.java
@@ -0,0 +1,39 @@
+package com.yahoo.search.searchchain;
+
+import com.yahoo.concurrent.ThreadFactoryFactory;
+
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.RejectedExecutionException;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Factory of the executor passed to renderers by default.
+ *
+ * @author bratseth
+ */
+class RenderingExecutorFactory {
+
+    private final int maxQueuedRenderingTasksPerProcessor;
+    private final int availableProcessors;
+
+    public RenderingExecutorFactory() {
+        this.maxQueuedRenderingTasksPerProcessor = 100;
+        this.availableProcessors = Runtime.getRuntime().availableProcessors();
+    }
+
+    ThreadPoolExecutor createExecutor() {
+        int maxOutstandingTasks = maxQueuedRenderingTasksPerProcessor * availableProcessors;
+        ThreadPoolExecutor executor = new ThreadPoolExecutor(availableProcessors, availableProcessors, 1L, TimeUnit.SECONDS,
+                                                             new LinkedBlockingQueue<>(maxOutstandingTasks),
+                                                             ThreadFactoryFactory.getThreadFactory("common-rendering"),
+                                                             (task, exec) -> renderingRejected(maxOutstandingTasks));
+        executor.prestartAllCoreThreads();
+        return executor;
+    }
+
+    private void renderingRejected(int maxOutstandingTasks) {
+        throw new RejectedExecutionException("More than " + maxOutstandingTasks + " rendering tasks queued, rejecting this");
+    }
+
+}