Create MessagePack singleton provider to avoid PermGen leak.

Prepare the MessagePack instance with a RadioMessage because generating
code for the MessagePack template registry is not thread-safe.

Before this, a new MessagePack instance got created for each processed
message which eventually lead to PermGen exhaustion. Not sure why the
generated classes haven't been garbage collected. (bug in msgpack?)

Fixes #907.

graylog2-shared/src/main/java/org/graylog2/shared/bindings/GenericBindings.java

@@ -30,16 +30,18 @@
 import org.graylog2.plugin.inputs.MessageInput;
 import org.graylog2.plugin.inputs.util.ThroughputCounter;
 import org.graylog2.plugin.system.NodeId;
-import org.graylog2.shared.buffers.InputBufferImpl;
-import org.graylog2.shared.buffers.ProcessBuffer;
-import org.graylog2.shared.buffers.processors.DecodingProcessor;
 import org.graylog2.shared.bindings.providers.EventBusProvider;
+import org.graylog2.shared.bindings.providers.MessagePackProvider;
 import org.graylog2.shared.bindings.providers.MetricRegistryProvider;
 import org.graylog2.shared.bindings.providers.NodeIdProvider;
 import org.graylog2.shared.bindings.providers.ServiceManagerProvider;
+import org.graylog2.shared.buffers.InputBufferImpl;
+import org.graylog2.shared.buffers.ProcessBuffer;
+import org.graylog2.shared.buffers.processors.DecodingProcessor;
 import org.graylog2.shared.inputs.InputRegistry;
 import org.graylog2.shared.stats.ThroughputStats;
 import org.jboss.netty.util.HashedWheelTimer;
+import org.msgpack.MessagePack;
 
 import java.util.concurrent.Semaphore;
 
@@ -77,5 +79,7 @@ protected void configure() {
         install(new FactoryModuleBuilder().build(new TypeLiteral<IOState.Factory<MessageInput>>(){}));
 
         bind(InputRegistry.class).asEagerSingleton();
+
+        bind(MessagePack.class).toProvider(MessagePackProvider.class).in(Scopes.SINGLETON);
     }
 }

graylog2-shared/src/main/java/org/graylog2/shared/bindings/providers/MessagePackProvider.java

@@ -0,0 +1,50 @@
+/**
+ * This file is part of Graylog2.
+ *
+ * Graylog2 is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Graylog2 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Graylog2.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.graylog2.shared.bindings.providers;
+
+import org.graylog2.plugin.RadioMessage;
+import org.msgpack.MessagePack;
+
+import javax.inject.Provider;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+/**
+ * MessagePack generates classes for each new instance and message type which can leak into PermGen.
+ *
+ * Must be a singleton provider!
+ */
+public class MessagePackProvider implements Provider<MessagePack> {
+    @Override
+    public MessagePack get() {
+        final MessagePack messagePack = new MessagePack();
+
+        try {
+            // Eagerly generate RadioMessage classes in the MessagePack object to avoid doing it on runtime.
+            // The generated code is thread-safe, but generating it is not.
+            final RadioMessage radioMessage = new RadioMessage();
+            final ByteArrayOutputStream stream = new ByteArrayOutputStream();
+            messagePack.write(stream, radioMessage);
+            final byte[] bytes = stream.toByteArray();
+            messagePack.read(bytes, RadioMessage.class);
+        } catch (IOException ignore) {
+        }
+
+        return messagePack;
+    }
+}