#67 live option implemented to collect live objects' stat

vjmap/README.md

@@ -66,6 +66,12 @@ vjmap的运行需要一段时间，如果中途需要停止执行，请使用kil
 ./vjmap.sh -all:minsize=1024,byname PID > /tmp/histo.log
 ```
 
+## 2.4 打印老年代中对象的统计信息，仅输出存活对象:
+
+```
+./vjmap.sh -old:live PID > /tmp/histo-old.log
+```
+
 # 3.输出示例
 
 

vjmap/README_EN.md

@@ -28,7 +28,7 @@ execute `kill -18 <PID_OF_TARGET_APP>` TWICE to awaken the target app.
 ## 2.1 Commands
 
 ```
-// Prints object stats of all the heap, ordered by their respective size in total.
+// Prints object stats of all gens, ordered by their respective size in total.
 ./vjmap.sh -all PID > /tmp/histo.log
 
 // Prints oldgen object stats, ordered by size in OldGen. Only CMS is supported for this option. 
@@ -70,6 +70,12 @@ for the CMS oldgen
 ./vjmap.sh -sur:minsize=1024,byname PID > /tmp/histo-sur.log
 ```
 
+## 2.4 Prints object stats of old gen, live objects only:
+
+```
+./vjmap.sh -old:live PID > /tmp/histo-old.log
+```
+
 # 3.Outputs
 
 ## 3.1 Count Survivor Objects over the Age of 3.

vjmap/pom.xml

@@ -9,6 +9,7 @@
 	<properties>
 		<!-- change it to point to your sa-jdi.jar from your JDK -->
 		<sajdijar>${java.home}/../lib/sa-jdi.jar</sajdijar>
+		<toolsjar>${java.home}/../lib/tools.jar</toolsjar>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<java.version>1.7</java.version>
 		<maven.compiler.source>${java.version}</maven.compiler.source>
@@ -23,6 +24,13 @@
 			<scope>system</scope>
 			<systemPath>${sajdijar}</systemPath>
 		</dependency>
+		<dependency>
+			<groupId>com.sun</groupId>
+			<artifactId>tools</artifactId>
+			<version>${java.version}</version>
+			<scope>system</scope>
+			<systemPath>${toolsjar}</systemPath>
+		</dependency>
 	</dependencies>
 
 	<build>

vjmap/src/main/assembly/vjmap.sh

@@ -18,10 +18,17 @@ if [ ! -f "$SAJDI_PATH" ] ; then
 	exit 1
 fi
 
+TOOLS_PATH=$JAVA_HOME/lib/tools.jar
+
+if [ ! -f "$TOOLS_PATH" ] ; then
+	echo "$TOOLS_PATH doesn't exist !" >&2
+	exit 1
+fi
+
 echo -e "\033[31mWARNING!! STW(Stop-The-World) will be performed on your Java process, if this is NOT wanted, type 'Ctrl+C' to exit. \033[0m"
 
 DIR=$( cd $(dirname $0) ; pwd -P )
 JAVA_OPTS="-Xms512m -Xmx512m -Xmn400m -XX:+UseConcMarkSweepGC -XX:+TieredCompilation -Xverify:none -XX:AutoBoxCacheMax=20000"
 
 
-"$JAVA_HOME"/bin/java $JAVA_OPTS -classpath $DIR/vjmap.jar:$SAJDI_PATH com.vip.vjtools.vjmap.VJMap $*
+"$JAVA_HOME"/bin/java $JAVA_OPTS -classpath $DIR/vjmap.jar:$SAJDI_PATH:$TOOLS_PATH com.vip.vjtools.vjmap.VJMap $*

vjmap/src/main/java/com/vip/vjtools/vjmap/VJMap.java

@@ -1,8 +1,11 @@
 package com.vip.vjtools.vjmap;
 
+import java.io.IOException;
+import java.io.InputStream;
 import java.io.PrintStream;
 import java.util.List;
 
+import com.sun.tools.attach.VirtualMachine;
 import com.vip.vjtools.vjmap.oops.GenAddressAccessor;
 import com.vip.vjtools.vjmap.oops.HeapHistogramVisitor;
 import com.vip.vjtools.vjmap.oops.LoadedClassAccessor;
@@ -12,6 +15,7 @@
 import sun.jvm.hotspot.HotSpotAgent;
 import sun.jvm.hotspot.oops.ObjectHeap;
 import sun.jvm.hotspot.runtime.VM;
+import sun.tools.attach.HotSpotVirtualMachine;;
 
 public class VJMap {
 
@@ -67,6 +71,8 @@ public static void main(String[] args) {
 		boolean orderByName = false;
 		long minSize = -1;
 		int minAge = 3;
+		boolean live = false;
+		// boolean dead = false;
 		if (!(args.length == 2 || args.length == 3)) {
 			printHelp();
 			return;
@@ -94,6 +100,8 @@ public static void main(String[] args) {
 						return;
 					}
 					minAge = Integer.parseInt(values[1]);
+				}  else if (addtionalFlag.toLowerCase().startsWith("live")) {
+					live = true;
 				}
 			}
 		}
@@ -108,8 +116,16 @@ public static void main(String[] args) {
 			coredumpPath = args[2];
 		}
 
+		if(live) {
+			if(pid == null) {
+				tty.println("only a running vm can be attached when live option is on");
+				return;
+			}
+			triggerGc(pid);
+		}
+
 		HotSpotAgent agent = new HotSpotAgent();
-
+		
 		try {
 			if (args.length == 2) {
 				agent.attach(pid);
@@ -149,6 +165,40 @@ public static void main(String[] args) {
 		}
 	}
 
+	/**
+	 * Trigger a remote gc using HotSpotVirtualMachine, inspired by jcmd's source code.
+	 * 
+	 * @param pid
+	 */
+	private static void triggerGc(Integer pid) {
+		VirtualMachine vm = null;
+		try {
+			vm = VirtualMachine.attach(String.valueOf(pid));
+			HotSpotVirtualMachine hvm = (HotSpotVirtualMachine) vm;
+			try (InputStream in = hvm.executeJCmd("GC.run");) {
+				byte b[] = new byte[256];
+				int n;
+				do {
+					n = in.read(b);
+					if (n > 0) {
+						String s = new String(b, 0, n, "UTF-8");
+						tty.print(s);
+					}
+				} while (n > 0);
+				tty.println();
+			}
+		} catch (Exception e) {
+			tty.println(e.getMessage());
+		} finally {
+			if (vm != null) {
+				try {
+					vm.detach();
+				} catch (IOException e) {
+					tty.println(e.getMessage());
+				}
+			}
+		}
+	}
 
 	private static void printHelp() {
 		int leftLength = "-all:minsize=1024,byname".length();
@@ -163,6 +213,7 @@ private static void printHelp() {
 				"print all gens histogram, total size>=1024, order by class name");
 
 		tty.printf(format, "-old", "print oldgen histogram, order by oldgen size");
+		tty.printf(format, "-old:live", "print oldgen histogram, live objects only");
 		tty.printf(format, "-old:minsize=1024", "print oldgen histogram, oldgen size>=1024");
 		tty.printf(format, "-old:minsize=1024,byname",
 				"print oldgen histogram, oldgen size>=1024, order by class name");