Use a dedicated thread for VIP status

Also, various nonfunctiuonal changes.

3 files changed, 19 insertions, 5 deletions

diff --git a/container-core/src/main/java/com/yahoo/container/handler/ThreadPoolProvider.java b/container-core/src/main/java/com/yahoo/container/handler/ThreadPoolProvider.java
index 474c2f1a4a2..bd8e9e1601d 100644
--- a/container-core/src/main/java/com/yahoo/container/handler/ThreadPoolProvider.java
+++ b/container-core/src/main/java/com/yahoo/container/handler/ThreadPoolProvider.java
@@ -22,7 +22,7 @@ import com.yahoo.jdisc.Metric;
  * A configurable thread pool provider. This provides the worker threads used for normal request processing.
  * Request an Executor injected in your component constructor if you want to use it.
  *
- * @author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
+ * @author Steinar Knutsen
  * @author baldersheim
  * @author bratseth
  */
diff --git a/container-core/src/main/java/com/yahoo/container/handler/VipStatusHandler.java b/container-core/src/main/java/com/yahoo/container/handler/VipStatusHandler.java
index f36cd77c0b7..7a244bc94cb 100644
--- a/container-core/src/main/java/com/yahoo/container/handler/VipStatusHandler.java
+++ b/container-core/src/main/java/com/yahoo/container/handler/VipStatusHandler.java
@@ -7,6 +7,9 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.util.concurrent.Executor;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
 import java.util.logging.Logger;
 
 import com.google.inject.Inject;
@@ -23,7 +26,8 @@ import com.yahoo.vespa.defaults.Defaults;
  * Transmit status to VIP from file or memory. Bind this to
  * "http://{@literal *}/status.html" to serve VIP status requests.
  *
- * @author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
+ * @author Steinar Knutsen
+ * @author bratseth
  */
 public final class VipStatusHandler extends ThreadedHttpRequestHandler {
 
@@ -160,13 +164,23 @@ public final class VipStatusHandler extends ThreadedHttpRequestHandler {
 
     @Inject
     public VipStatusHandler(Executor executor, VipStatusConfig vipConfig, Metric metric, VipStatus vipStatus) {
-        super(executor, metric);
+        super(createDedicatedThreadExecutor(), metric);
         this.accessDisk = vipConfig.accessdisk();
         this.statusFile = new File(Defaults.getDefaults().underVespaHome(vipConfig.statusfile()));
         this.noSearchBackendsImpliesOutOfService = vipConfig.noSearchBackendsImpliesOutOfService();
         this.vipStatus = vipStatus;
     }
 
+    /**
+     * Use a dedicated thread pool to avoid returning an error to VIPs when the regular thread pool is out of capacity.
+     * One thread should be enough for status handling - otherwise something else is completely wrong, 
+     * in which case this will eventually start returning a 503 (due to work rejection) as the bounded 
+     * queue will fill up
+     */
+    private static Executor createDedicatedThreadExecutor() {
+        return new ThreadPoolExecutor(1, 1, 0, TimeUnit.SECONDS, new LinkedBlockingQueue<>(100));
+    }
+
     @Override
     public HttpResponse handle(HttpRequest request) {
         if (metric != null)
diff --git a/container-core/src/main/java/com/yahoo/container/jdisc/ThreadedHttpRequestHandler.java b/container-core/src/main/java/com/yahoo/container/jdisc/ThreadedHttpRequestHandler.java
index 6600a36f9db..07af6d45aed 100644
--- a/container-core/src/main/java/com/yahoo/container/jdisc/ThreadedHttpRequestHandler.java
+++ b/container-core/src/main/java/com/yahoo/container/jdisc/ThreadedHttpRequestHandler.java
@@ -24,14 +24,14 @@ import java.util.logging.Logger;
  * {@link HttpResponse#render(java.io.OutputStream)} method.
  *
  * @author hmusum
- * @author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
+ * @author Steinar Knutsen
  * @author bratseth
  * @since 5.1
  */
 public abstract class ThreadedHttpRequestHandler extends ThreadedRequestHandler {
 
     public static final String CONTENT_TYPE = "Content-Type";
-    public static final String DATE = "Date";
+    public static final String DATE = "Date"; // TODO: Remove on Vespa 7
     private static final String RENDERING_ERRORS = "rendering_errors";
 
     /** Logger for subclasses */