Does OpenJ9 support sun.misc.Contended annotation?
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I've created a program to check if @sun.misc.Contended is in effect. The idea is that when @Contended is in effect, the field offsets in annotated class will be larger.
I can see the expected difference in offsets on OpenJDK, if I specify the -XX:-RestrictContended flag. I do not see any difference on OpenJ9 11 (jdk-11.0.1+13, Eclipse OpenJ9 VM-11.0.1) through.
The OpenJDK output is
readOnly: 12
writeOnly: 16
----
readOnly: 12
writeOnly: 144
The OpenJ9 output is
readOnly: 8
writeOnly: 12
----
readOnly: 8
writeOnly: 12
The program is
import sun.misc.Unsafe;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
public class Main {
public static class Baseline {
int readOnly;
int writeOnly;
}
public static class Contended {
int readOnly;
@sun.misc.Contended
int writeOnly;
}
public static void main(String args) throws Exception {
Baseline b = new Baseline();
Contended s = new Contended();
printOffsets(b);
System.out.println("----");
printOffsets(s);
}
// https://blog.hazelcast.com/using-sun-misc-unsafe-in-java-9/
@SuppressWarnings("restriction")
private static Unsafe getUnsafe() throws NoSuchFieldException, IllegalAccessException {
Field singleoneInstanceField = Unsafe.class.getDeclaredField("theUnsafe");
singleoneInstanceField.setAccessible(true);
return (Unsafe) singleoneInstanceField.get(null);
}
// http://mishadoff.com/blog/java-magic-part-4-sun-dot-misc-dot-unsafe/
public static void printOffsets(Object o) throws Exception {
Unsafe u = getUnsafe();
Class c = o.getClass();
for (Field f : c.getDeclaredFields()) {
if ((f.getModifiers() & Modifier.STATIC) == 0) {
printOffset(u, f);
}
}
}
public static void printOffset(Unsafe u, Field f) {
long offset = u.objectFieldOffset(f);
System.out.println(f.getName() + ": " + offset);
}
}
java ibm-jvm openj9
asked Nov 16 '18 at 15:48
user7610user7610
8,97446178
add a comment |
0
I've created a program to check if @sun.misc.Contended is in effect. The idea is that when @Contended is in effect, the field offsets in annotated class will be larger.
I can see the expected difference in offsets on OpenJDK, if I specify the -XX:-RestrictContended flag. I do not see any difference on OpenJ9 11 (jdk-11.0.1+13, Eclipse OpenJ9 VM-11.0.1) through.
The OpenJDK output is
readOnly: 12
writeOnly: 16
----
readOnly: 12
writeOnly: 144
The OpenJ9 output is
readOnly: 8
writeOnly: 12
----
readOnly: 8
writeOnly: 12
The program is
import sun.misc.Unsafe;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
public class Main {
public static class Baseline {
int readOnly;
int writeOnly;
}
public static class Contended {
int readOnly;
@sun.misc.Contended
int writeOnly;
}
public static void main(String args) throws Exception {
Baseline b = new Baseline();
Contended s = new Contended();
printOffsets(b);
System.out.println("----");
printOffsets(s);
}
// https://blog.hazelcast.com/using-sun-misc-unsafe-in-java-9/
@SuppressWarnings("restriction")
private static Unsafe getUnsafe() throws NoSuchFieldException, IllegalAccessException {
Field singleoneInstanceField = Unsafe.class.getDeclaredField("theUnsafe");
singleoneInstanceField.setAccessible(true);
return (Unsafe) singleoneInstanceField.get(null);
}
// http://mishadoff.com/blog/java-magic-part-4-sun-dot-misc-dot-unsafe/
public static void printOffsets(Object o) throws Exception {
Unsafe u = getUnsafe();
Class c = o.getClass();
for (Field f : c.getDeclaredFields()) {
if ((f.getModifiers() & Modifier.STATIC) == 0) {
printOffset(u, f);
}
}
}
public static void printOffset(Unsafe u, Field f) {
long offset = u.objectFieldOffset(f);
System.out.println(f.getName() + ": " + offset);
}
}
java ibm-jvm openj9
asked Nov 16 '18 at 15:48
user7610user7610
8,97446178
helpful discussion on OpenJ9 chat openj9.slack.com/archives/C862YFGL9/p1542383521060200
– user7610
Nov 16 '18 at 16:46
feature request github.com/eclipse/openj9/issues/3716
– user7610
Nov 16 '18 at 19:50
add a comment |
0
0
0
I've created a program to check if @sun.misc.Contended is in effect. The idea is that when @Contended is in effect, the field offsets in annotated class will be larger.
I can see the expected difference in offsets on OpenJDK, if I specify the -XX:-RestrictContended flag. I do not see any difference on OpenJ9 11 (jdk-11.0.1+13, Eclipse OpenJ9 VM-11.0.1) through.
The OpenJDK output is
readOnly: 12
writeOnly: 16
----
readOnly: 12
writeOnly: 144
The OpenJ9 output is
readOnly: 8
writeOnly: 12
----
readOnly: 8
writeOnly: 12
The program is
import sun.misc.Unsafe;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
public class Main {
public static class Baseline {
int readOnly;
int writeOnly;
}
public static class Contended {
int readOnly;
@sun.misc.Contended
int writeOnly;
}
public static void main(String args) throws Exception {
Baseline b = new Baseline();
Contended s = new Contended();
printOffsets(b);
System.out.println("----");
printOffsets(s);
}
// https://blog.hazelcast.com/using-sun-misc-unsafe-in-java-9/
@SuppressWarnings("restriction")
private static Unsafe getUnsafe() throws NoSuchFieldException, IllegalAccessException {
Field singleoneInstanceField = Unsafe.class.getDeclaredField("theUnsafe");
singleoneInstanceField.setAccessible(true);
return (Unsafe) singleoneInstanceField.get(null);
}
// http://mishadoff.com/blog/java-magic-part-4-sun-dot-misc-dot-unsafe/
public static void printOffsets(Object o) throws Exception {
Unsafe u = getUnsafe();
Class c = o.getClass();
for (Field f : c.getDeclaredFields()) {
if ((f.getModifiers() & Modifier.STATIC) == 0) {
printOffset(u, f);
}
}
}
public static void printOffset(Unsafe u, Field f) {
long offset = u.objectFieldOffset(f);
System.out.println(f.getName() + ": " + offset);
}
}
java ibm-jvm openj9
asked Nov 16 '18 at 15:48
user7610user7610
8,97446178
I've created a program to check if @sun.misc.Contended is in effect. The idea is that when @Contended is in effect, the field offsets in annotated class will be larger.
I can see the expected difference in offsets on OpenJDK, if I specify the -XX:-RestrictContended flag. I do not see any difference on OpenJ9 11 (jdk-11.0.1+13, Eclipse OpenJ9 VM-11.0.1) through.
The OpenJDK output is
readOnly: 12
writeOnly: 16
----
readOnly: 12
writeOnly: 144
The OpenJ9 output is
readOnly: 8
writeOnly: 12
----
readOnly: 8
writeOnly: 12
The program is
import sun.misc.Unsafe;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
public class Main {
public static class Baseline {
int readOnly;
int writeOnly;
}
public static class Contended {
int readOnly;
@sun.misc.Contended
int writeOnly;
}
public static void main(String args) throws Exception {
Baseline b = new Baseline();
Contended s = new Contended();
printOffsets(b);
System.out.println("----");
printOffsets(s);
}
// https://blog.hazelcast.com/using-sun-misc-unsafe-in-java-9/
@SuppressWarnings("restriction")
private static Unsafe getUnsafe() throws NoSuchFieldException, IllegalAccessException {
Field singleoneInstanceField = Unsafe.class.getDeclaredField("theUnsafe");
singleoneInstanceField.setAccessible(true);
return (Unsafe) singleoneInstanceField.get(null);
}
// http://mishadoff.com/blog/java-magic-part-4-sun-dot-misc-dot-unsafe/
public static void printOffsets(Object o) throws Exception {
Unsafe u = getUnsafe();
Class c = o.getClass();
for (Field f : c.getDeclaredFields()) {
if ((f.getModifiers() & Modifier.STATIC) == 0) {
printOffset(u, f);
}
}
}
public static void printOffset(Unsafe u, Field f) {
long offset = u.objectFieldOffset(f);
System.out.println(f.getName() + ": " + offset);
}
}
java ibm-jvm openj9
java ibm-jvm openj9
asked Nov 16 '18 at 15:48
user7610user7610
8,97446178
asked Nov 16 '18 at 15:48
user7610user7610
8,97446178
asked Nov 16 '18 at 15:48
user7610user7610
8,97446178
asked Nov 16 '18 at 15:48
user7610user7610
8,97446178
asked Nov 16 '18 at 15:48
user7610user7610
8,97446178
8,97446178
helpful discussion on OpenJ9 chat openj9.slack.com/archives/C862YFGL9/p1542383521060200
– user7610
Nov 16 '18 at 16:46
feature request github.com/eclipse/openj9/issues/3716
– user7610
Nov 16 '18 at 19:50
add a comment |
helpful discussion on OpenJ9 chat openj9.slack.com/archives/C862YFGL9/p1542383521060200
– user7610
Nov 16 '18 at 16:46
feature request github.com/eclipse/openj9/issues/3716
– user7610
Nov 16 '18 at 19:50
helpful discussion on OpenJ9 chat openj9.slack.com/archives/C862YFGL9/p1542383521060200
– user7610
Nov 16 '18 at 16:46
helpful discussion on OpenJ9 chat openj9.slack.com/archives/C862YFGL9/p1542383521060200
– user7610
Nov 16 '18 at 16:46
feature request github.com/eclipse/openj9/issues/3716
– user7610
Nov 16 '18 at 19:50
feature request github.com/eclipse/openj9/issues/3716
– user7610
Nov 16 '18 at 19:50
add a comment |
1 Answer
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At present, OpenJ9 supports @Contended at the class level only.
answered Nov 16 '18 at 16:44
Peter BainPeter Bain
361
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
1
At present, OpenJ9 supports @Contended at the class level only.
answered Nov 16 '18 at 16:44
Peter BainPeter Bain
361
add a comment |
1
At present, OpenJ9 supports @Contended at the class level only.
answered Nov 16 '18 at 16:44
Peter BainPeter Bain
361
add a comment |
1
1
1
At present, OpenJ9 supports @Contended at the class level only.
answered Nov 16 '18 at 16:44
Peter BainPeter Bain
361
At present, OpenJ9 supports @Contended at the class level only.
answered Nov 16 '18 at 16:44
Peter BainPeter Bain
361
answered Nov 16 '18 at 16:44
Peter BainPeter Bain
361
answered Nov 16 '18 at 16:44
Peter BainPeter Bain
361
answered Nov 16 '18 at 16:44
Peter BainPeter Bain
361
361
add a comment |
add a comment |
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helpful discussion on OpenJ9 chat openj9.slack.com/archives/C862YFGL9/p1542383521060200
– user7610
Nov 16 '18 at 16:46
feature request github.com/eclipse/openj9/issues/3716
– user7610
Nov 16 '18 at 19:50