Added tool to attach at runtime the agent

OpenJDK based, depends on:
- JAVA_HOME set to a JDK instalation
- OpenJDK tools.jar available locally for compilation

attach-client.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+AGENT_PATH=`ls -1 $DIR/target/jvm-profiler-*.jar`
+echo $AGENT_PATH
+
+java -cp $AGENT_PATH:$JAVA_HOME/lib/tools.jar com.uber.profiling.tools.AttachClient $AGENT_PATH $*
+

pom.xml

@@ -81,7 +81,13 @@
             <version>4.8.1</version>
             <scope>test</scope>
         </dependency>
-
+
+        <!-- required for AttachClient build -->
+        <dependency>
+            <groupId>com.github.olivergondza</groupId>
+            <artifactId>maven-jdk-tools-wrapper</artifactId>
+            <version>0.1</version>
+        </dependency>
     </dependencies>
 
     <build>

src/main/java/com/uber/profiling/tools/AttachClient.java

@@ -0,0 +1,20 @@
+package com.uber.profiling.tools;
+
+import com.sun.tools.attach.VirtualMachine;
+
+public class AttachClient {
+
+  public static void main(String[] args) throws Exception {
+    if (args.length != 3) {
+      System.out.println("Usage: com.uber.profiling.tools.AttachClient <agent_jar_full_path> <agent_args> <vm_pid>");
+      return;
+    }
+    String agent_path = args[0];
+    String agent_args = args[1];
+    String pid = args[2];
+    VirtualMachine vm = VirtualMachine.attach(pid);
+    System.out.println("vm = " + vm);
+    vm.loadAgent(agent_path, agent_args);
+    vm.detach();
+  }
+}