Short summary:
\nEscape analysis is not enabled by default in JDK 6, and it’s available only in server JVM<\/p>\n
Thus in order to enable Escape analysis, following parameters for java are required:
\n[code]
\njava -server -XX:+DoEscapeAnalysis
\n[\/code]<\/p>\n
So lets run run the test from the references…<\/p>\n
Test Program<\/b>
\n[code lang=”java”]
\npackage org.kari.test;<\/p>\n
public class LockTest {
\n \/\/ 20 million .
\n private static final int MAX = 20000000;<\/p>\n
public static void main(String[] args)
\n throws InterruptedException
\n {
\n \/\/ warm up the method cache
\n concatBuffer(”Josh”, ”James”, ”Duke”);
\n concatBuilder(”Josh”, ”James”, ”Duke”);<\/p>\n
System.gc();
\n Thread.sleep(1000);
\n long start = System.currentTimeMillis();
\n for (int i = 0; i < MAX; i++) {\n concatBuffer(\"Josh\", \"James\", \"Duke\");\n }\n\n long bufferCost = System.currentTimeMillis() - start;\n System.out.println(\"StringBuffer: \" + bufferCost + \" ms.\");\n\n System.gc();\n Thread.sleep(1000);\n start = System.currentTimeMillis();\n for (int i = 0; i < MAX; i++) {\n concatBuilder(\"Josh\", \"James\", \"Duke\");\n }\n long builderCost = System.currentTimeMillis() - start;\n System.out.println(\"StringBuilder: \" + builderCost + \" ms.\");\n System.out.println(\"Thread safety overhead of StringBuffer: \"\n + ((bufferCost * 10000 \/ (builderCost * 100)) - 100) + \"%n\");\n }\n\n public static String concatBuffer(String s1, String s2, String s3) {\n StringBuffer sb = new StringBuffer();\n sb.append(s1);\n sb.append(s2);\n sb.append(s3);\n return sb.toString();\n }\n\n public static String concatBuilder(String s1, String s2, String s3) {\n StringBuilder sb = new StringBuilder();\n sb.append(s1);\n sb.append(s2);\n sb.append(s3);\n return sb.toString();\n }\n}\n[\/code]\n\nTest script:<\/b>
\n[code]
\nCP=”-cp bin”
\nMAIN=”org.kari.test.LockTest”
\n# 1
\nARGS=”-server -XX:-DoEscapeAnalysis -XX:-EliminateLocks -XX:-UseBiasedLocking”
\necho ””
\necho ”TEST: $ARGS”
\njava $CP $ARGS $MAIN<\/p>\n
# 2
\nARGS=”-server -XX:+DoEscapeAnalysis -XX:-EliminateLocks -XX:-UseBiasedLocking”
\necho ””
\necho ”TEST: $ARGS”
\njava $CP $ARGS $MAIN<\/p>\n
# 3
\nARGS=”-server -XX:-DoEscapeAnalysis -XX:+EliminateLocks -XX:-UseBiasedLocking”
\necho ””
\necho ”TEST: $ARGS”
\njava $CP $ARGS $MAIN<\/p>\n
# 4
\nARGS=”-server -XX:-DoEscapeAnalysis -XX:-EliminateLocks -XX:+UseBiasedLocking”
\necho ””
\necho ”TEST: $ARGS”
\njava $CP $ARGS $MAIN<\/p>\n
# 5
\nARGS=”-server -XX:-DoEscapeAnalysis -XX:+EliminateLocks -XX:+UseBiasedLocking”
\necho ””
\necho ”TEST: $ARGS”
\njava $CP $ARGS $MAIN<\/p>\n
# 6
\nARGS=”-server -XX:+DoEscapeAnalysis -XX:+EliminateLocks -XX:+UseBiasedLocking”
\necho ””
\necho ”TEST: $ARGS”
\njava $CP $ARGS $MAIN<\/p>\n
# 7
\nARGS=”-server”
\necho ””
\necho ”TEST: $ARGS”
\njava $CP $ARGS $MAIN<\/p>\n
# 8
\nARGS=”-client”
\necho ””
\necho ”TEST: $ARGS”
\njava $CP $ARGS $MAIN
\n[\/code]<\/p>\n
Results<\/b>
\n[code]
\nPicked up _JAVA_OPTIONS: -Xverify:none -Dsun.java2d.opengl=true
\nStringBuffer: 4854 ms.
\nStringBuilder: 3905 ms.
\nThread safety overhead of StringBuffer: 24%n<\/p>\n
TEST: -server -XX:+DoEscapeAnalysis -XX:-EliminateLocks -XX:-UseBiasedLocking
\nStringBuffer: 4850 ms.
\nStringBuilder: 4222 ms.
\nThread safety overhead of StringBuffer: 14%n<\/p>\n
TEST: -server -XX:-DoEscapeAnalysis -XX:+EliminateLocks -XX:-UseBiasedLocking
\nStringBuffer: 4598 ms.
\nStringBuilder: 4509 ms.
\nThread safety overhead of StringBuffer: 1%n<\/p>\n
TEST: -server -XX:-DoEscapeAnalysis -XX:-EliminateLocks -XX:+UseBiasedLocking
\nStringBuffer: 4679 ms.
\nStringBuilder: 3940 ms.
\nThread safety overhead of StringBuffer: 18%n<\/p>\n
TEST: -server -XX:-DoEscapeAnalysis -XX:+EliminateLocks -XX:+UseBiasedLocking
\nStringBuffer: 4835 ms.
\nStringBuilder: 4268 ms.
\nThread safety overhead of StringBuffer: 13%n<\/p>\n
TEST: -server -XX:+DoEscapeAnalysis -XX:+EliminateLocks -XX:+UseBiasedLocking
\nStringBuffer: 4989 ms.
\nStringBuilder: 4397 ms.
\nThread safety overhead of StringBuffer: 13%n<\/p>\n
TEST: -server
\nStringBuffer: 4389 ms.
\nStringBuilder: 3969 ms.
\nThread safety overhead of StringBuffer: 10%n<\/p>\n
TEST: -client
\nStringBuffer: 6441 ms.
\nStringBuilder: 5690 ms.
\nThread safety overhead of StringBuffer: 13%n
\n[\/code]<\/p>\n
NOTE:<\/b> I’ve following global java options in use in my system
\n[code]
\nexport _JAVA_OPTIONS=”-Xverify:none -Dsun.java2d.opengl=true”
\n[\/code]<\/p>\n