fix-1309 http connection enhancements

geowebcache/core/src/main/java/org/geowebcache/config/GeoWebCacheConfiguration.java

@@ -72,6 +72,8 @@ public class GeoWebCacheConfiguration {
 
     private Boolean wmtsCiteCompliant;
 
+    private HttpConnectionSettings httpConnectionSettings;
+
     /** The persisted list of layers */
     private List<TileLayer> layers;
 
@@ -286,4 +288,14 @@ public boolean isWmtsCiteCompliant() {
     public void setWmtsCiteCompliant(boolean wmtsCiteCompliant) {
         this.wmtsCiteCompliant = wmtsCiteCompliant;
     }
+
+    /** @return the HTTP connection settings */
+    public HttpConnectionSettings getHttpConnectionSettings() {
+        return httpConnectionSettings;
+    }
+
+    /** @param httpConnectionSettings the HTTP connection settings to set */
+    public void setHttpConnectionSettings(HttpConnectionSettings httpConnectionSettings) {
+        this.httpConnectionSettings = httpConnectionSettings;
+    }
 }

geowebcache/core/src/main/java/org/geowebcache/config/HttpConnectionSettings.java

@@ -0,0 +1,120 @@
+/**
+ * This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General
+ * Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * <p>This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ * <p>You should have received a copy of the GNU Lesser General Public License along with this program. If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * @author Lennart Juette, PTV AG (http://www.ptvag.com) 2010
+ */
+package org.geowebcache.config;
+
+import java.util.Objects;
+
+/**
+ * Configuration class for global HTTP connection settings used by all WMS layers. This replaces the per-layer
+ * concurrency parameter which was ineffective due to the static singleton connection manager.
+ */
+public class HttpConnectionSettings {
+
+    /** Default maximum total connections */
+    public static final int DEFAULT_MAX_CONNECTIONS_TOTAL = 20;
+
+    /** Default maximum connections per route */
+    public static final int DEFAULT_MAX_CONNECTIONS_PER_ROUTE = 2;
+
+    /** Default connection timeout in seconds */
+    public static final int DEFAULT_CONNECTION_TIMEOUT = 30;
+
+    /** Default socket timeout in seconds */
+    public static final int DEFAULT_SOCKET_TIMEOUT = 60;
+
+    private Integer maxConnectionsTotal;
+    private Integer maxConnectionsPerRoute;
+    private Integer connectionTimeout;
+    private Integer socketTimeout;
+
+    public HttpConnectionSettings() {
+        // Default constructor for XStream
+    }
+
+    public HttpConnectionSettings(
+            Integer maxConnectionsTotal,
+            Integer maxConnectionsPerRoute,
+            Integer connectionTimeout,
+            Integer socketTimeout) {
+        this.maxConnectionsTotal = maxConnectionsTotal;
+        this.maxConnectionsPerRoute = maxConnectionsPerRoute;
+        this.connectionTimeout = connectionTimeout;
+        this.socketTimeout = socketTimeout;
+    }
+
+    /** @return the maximum total number of connections in the connection pool */
+    public int getMaxConnectionsTotal() {
+        return maxConnectionsTotal != null ? maxConnectionsTotal : DEFAULT_MAX_CONNECTIONS_TOTAL;
+    }
+
+    /** @param maxConnectionsTotal the maximum total number of connections to set */
+    public void setMaxConnectionsTotal(Integer maxConnectionsTotal) {
+        this.maxConnectionsTotal = maxConnectionsTotal;
+    }
+
+    /** @return the maximum number of connections per route (per backend server) */
+    public int getMaxConnectionsPerRoute() {
+        return maxConnectionsPerRoute != null ? maxConnectionsPerRoute : DEFAULT_MAX_CONNECTIONS_PER_ROUTE;
+    }
+
+    /** @param maxConnectionsPerRoute the maximum connections per route to set */
+    public void setMaxConnectionsPerRoute(Integer maxConnectionsPerRoute) {
+        this.maxConnectionsPerRoute = maxConnectionsPerRoute;
+    }
+
+    /** @return the connection timeout in seconds */
+    public int getConnectionTimeout() {
+        return connectionTimeout != null ? connectionTimeout : DEFAULT_CONNECTION_TIMEOUT;
+    }
+
+    /** @param connectionTimeout the connection timeout to set */
+    public void setConnectionTimeout(Integer connectionTimeout) {
+        this.connectionTimeout = connectionTimeout;
+    }
+
+    /** @return the socket timeout in seconds */
+    public int getSocketTimeout() {
+        return socketTimeout != null ? socketTimeout : DEFAULT_SOCKET_TIMEOUT;
+    }
+
+    /** @param socketTimeout the socket timeout to set */
+    public void setSocketTimeout(Integer socketTimeout) {
+        this.socketTimeout = socketTimeout;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null || getClass() != obj.getClass()) return false;
+        HttpConnectionSettings that = (HttpConnectionSettings) obj;
+        return Objects.equals(maxConnectionsTotal, that.maxConnectionsTotal)
+                && Objects.equals(maxConnectionsPerRoute, that.maxConnectionsPerRoute)
+                && Objects.equals(connectionTimeout, that.connectionTimeout)
+                && Objects.equals(socketTimeout, that.socketTimeout);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(maxConnectionsTotal, maxConnectionsPerRoute, connectionTimeout, socketTimeout);
+    }
+
+    @Override
+    public String toString() {
+        return "HttpConnectionSettings{" + "maxConnectionsTotal="
+                + getMaxConnectionsTotal() + ", maxConnectionsPerRoute="
+                + getMaxConnectionsPerRoute() + ", connectionTimeout="
+                + getConnectionTimeout() + ", socketTimeout="
+                + getSocketTimeout() + '}';
+    }
+}

geowebcache/core/src/main/java/org/geowebcache/config/XMLConfiguration.java

@@ -88,6 +88,7 @@
 import org.geowebcache.storage.UnsuitableStorageException;
 import org.geowebcache.util.ApplicationContextProvider;
 import org.geowebcache.util.ExceptionUtils;
+import org.geowebcache.util.HttpClientConnectionManagerFactory;
 import org.geowebcache.util.URLs;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -799,6 +800,9 @@ public void afterPropertiesSet() throws GeoWebCacheException {
 
         this.setGwcConfig(loadConfiguration());
 
+        // Initialize HTTP connection manager with configuration settings
+        initializeHttpConnectionManager();
+
         log.config("Initializing GridSets from " + getIdentifier());
 
         getGridSetsInternal();
@@ -853,6 +857,29 @@ private void initialize(final TileLayer layer) {
         layer.initialize(gridSetBroker);
     }
 
+    /**
+     * Initialize the HTTP connection manager with settings from the configuration. This replaces the static singleton
+     * approach with a configurable solution.
+     */
+    private void initializeHttpConnectionManager() {
+        try {
+            HttpConnectionSettings settings = getGwcConfig().getHttpConnectionSettings();
+            if (settings == null) {
+                // Use default settings if none configured
+                settings = new HttpConnectionSettings();
+                log.info("No HTTP connection settings found in configuration, using defaults: " + settings);
+            } else {
+                log.info("Initializing HTTP connection manager with settings: " + settings);
+            }
+
+            HttpClientConnectionManagerFactory.getInstance().initialize(settings);
+        } catch (Exception e) {
+            log.warning("Failed to initialize HTTP connection manager with configuration settings: " + e.getMessage());
+            // Fall back to default settings
+            HttpClientConnectionManagerFactory.getInstance().initialize(new HttpConnectionSettings());
+        }
+    }
+
     /** @see TileLayerConfiguration#getIdentifier() */
     @Override
     public String getIdentifier() {

geowebcache/core/src/main/java/org/geowebcache/layer/wms/WMSLayer.java

@@ -106,6 +106,11 @@ public enum HttpRequestMode {
     @SuppressWarnings("unused")
     private String cachePrefix;
 
+    /**
+     * @deprecated This parameter is deprecated and ineffective due to the static singleton connection manager. Use
+     *     global HTTP connection settings in geowebcache.xml instead.
+     */
+    @Deprecated
     private Integer concurrency;
 
     // private transient int expireCacheInt = -1;
@@ -685,6 +690,9 @@ public void setSourceHelper(WMSSourceHelper source) {
         log.fine("Setting sourceHelper on " + this.name);
         this.sourceHelper = source;
         if (concurrency != null) {
+            log.warning("Layer '" + this.name + "' uses deprecated 'concurrency' parameter. "
+                    + "This parameter is ineffective due to the static singleton connection manager. "
+                    + "Use global HTTP connection settings in geowebcache.xml instead.");
             this.sourceHelper.setConcurrency(concurrency);
         } else {
             this.sourceHelper.setConcurrency(32);

geowebcache/core/src/main/java/org/geowebcache/util/HttpClientBuilder.java

@@ -20,9 +20,7 @@
 import org.apache.http.client.HttpClient;
 import org.apache.http.client.config.CookieSpecs;
 import org.apache.http.client.config.RequestConfig;
-import org.apache.http.conn.HttpClientConnectionManager;
 import org.apache.http.impl.client.BasicCredentialsProvider;
-import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
 import org.geotools.util.logging.Logging;
 
 /** Builder class for HttpClients */
@@ -35,7 +33,8 @@ public class HttpClientBuilder {
     private AuthScope authscope = null;
 
     private Integer backendTimeoutMillis = null;
-    private static final HttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();
+    private static final HttpClientConnectionManagerFactory connectionManagerFactory =
+            HttpClientConnectionManagerFactory.getInstance();
 
     private boolean doAuthentication = false;
 
@@ -71,8 +70,9 @@ public HttpClientBuilder(
 
         clientBuilder = org.apache.http.impl.client.HttpClientBuilder.create();
         clientBuilder.useSystemProperties();
-        clientBuilder.setConnectionManager(connectionManager);
-        clientBuilder.setMaxConnTotal(concurrency);
+        clientBuilder.setConnectionManager(connectionManagerFactory.getConnectionManager());
+        // Note: concurrency parameter is now handled globally via HttpConnectionSettings
+        // The per-layer concurrency parameter is deprecated and ineffective
     }
 
     /*

geowebcache/core/src/main/java/org/geowebcache/util/HttpClientConnectionManagerFactory.java

@@ -0,0 +1,122 @@
+/**
+ * This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General
+ * Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * <p>This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ * <p>You should have received a copy of the GNU Lesser General Public License along with this program. If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * @author Lennart Juette, PTV AG (http://www.ptvag.com) 2010
+ */
+package org.geowebcache.util;
+
+import java.util.logging.Logger;
+import org.apache.http.conn.HttpClientConnectionManager;
+import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
+import org.geotools.util.logging.Logging;
+import org.geowebcache.config.HttpConnectionSettings;
+
+/**
+ * Factory class for creating and managing HTTP connection managers. This replaces the static singleton approach with a
+ * configurable solution that properly respects the connection settings.
+ */
+public class HttpClientConnectionManagerFactory {
+
+    static final Logger log = Logging.getLogger(HttpClientConnectionManagerFactory.class.toString());
+
+    private static volatile HttpClientConnectionManagerFactory instance;
+    private volatile HttpClientConnectionManager connectionManager;
+    private volatile HttpConnectionSettings settings;
+
+    private HttpClientConnectionManagerFactory() {
+        // Private constructor for singleton
+    }
+
+    /** Get the singleton instance of the factory */
+    public static HttpClientConnectionManagerFactory getInstance() {
+        if (instance == null) {
+            synchronized (HttpClientConnectionManagerFactory.class) {
+                if (instance == null) {
+                    instance = new HttpClientConnectionManagerFactory();
+                }
+            }
+        }
+        return instance;
+    }
+
+    /**
+     * Initialize the connection manager with the given settings. This method should be called once during application
+     * startup.
+     *
+     * @param settings the HTTP connection settings to use
+     */
+    public synchronized void initialize(HttpConnectionSettings settings) {
+        if (this.settings != null && this.settings.equals(settings)) {
+            // Settings haven't changed, no need to recreate
+            return;
+        }
+
+        this.settings = settings != null ? settings : new HttpConnectionSettings();
+
+        // Close existing connection manager if it exists
+        if (connectionManager != null) {
+            try {
+                connectionManager.shutdown();
+            } catch (Exception e) {
+                log.warning("Error closing existing connection manager: " + e.getMessage());
+            }
+        }
+
+        // Create new connection manager with proper settings
+        PoolingHttpClientConnectionManager newManager = new PoolingHttpClientConnectionManager();
+        newManager.setMaxTotal(this.settings.getMaxConnectionsTotal());
+        newManager.setDefaultMaxPerRoute(this.settings.getMaxConnectionsPerRoute());
+
+        this.connectionManager = newManager;
+
+        log.info("Initialized HTTP connection manager with settings: " + this.settings);
+    }
+
+    /**
+     * Get the current connection manager. If not initialized, creates one with default settings.
+     *
+     * @return the HTTP connection manager
+     */
+    public HttpClientConnectionManager getConnectionManager() {
+        if (connectionManager == null) {
+            synchronized (this) {
+                if (connectionManager == null) {
+                    // Initialize with default settings if not already done
+                    initialize(new HttpConnectionSettings());
+                }
+            }
+        }
+        return connectionManager;
+    }
+
+    /**
+     * Get the current connection settings
+     *
+     * @return the current HTTP connection settings
+     */
+    public HttpConnectionSettings getSettings() {
+        return settings != null ? settings : new HttpConnectionSettings();
+    }
+
+    /** Shutdown the connection manager and release resources. This should be called during application shutdown. */
+    public synchronized void shutdown() {
+        if (connectionManager != null) {
+            try {
+                connectionManager.shutdown();
+                connectionManager = null;
+                settings = null;
+                log.info("HTTP connection manager shutdown completed");
+            } catch (Exception e) {
+                log.warning("Error during connection manager shutdown: " + e.getMessage());
+            }
+        }
+    }
+}

geowebcache/core/src/main/resources/geowebcache.xml

@@ -99,6 +99,13 @@
 
   </blobStores>
 
+  <httpConnectionSettings>
+    <maxConnectionsTotal>20</maxConnectionsTotal>
+    <maxConnectionsPerRoute>6</maxConnectionsPerRoute>
+    <connectionTimeout>30</connectionTimeout>
+    <socketTimeout>60</socketTimeout>
+  </httpConnectionSettings>
+
   <gridSets>
     <!-- Grid Set Example, by default EPSG:900913 and EPSG:4326 are defined -->
     <gridSet>