-
-
Save charleehu/1703466 to your computer and use it in GitHub Desktop.
An Serviceability-Agent based tool to see stats of NIO direct memory, as an alternative on JDKs without JMX support for direct memory monitoring.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| $ java -version | |
| java version "1.6.0_30" | |
| Java(TM) SE Runtime Environment (build 1.6.0_30-b12) | |
| Java HotSpot(TM) 64-Bit Server VM (build 20.5-b03, mixed mode) | |
| $ javac -classpath $JAVA_HOME/lib/sa-jdi.jar DirectMemorySize.java | |
| $ jps | |
| 18486 GroovyStarter | |
| 23135 Jps | |
| $ java -classpath .:$JAVA_HOME/lib/sa-jdi.jar DirectMemorySize `pgrep java` | |
| Attaching to process ID 18486, please wait... | |
| Debugger attached successfully. | |
| Server compiler detected. | |
| JVM version is 20.5-b03 | |
| NIO direct memory: (in bytes) | |
| reserved size = 0.000000 MB (0 bytes) | |
| max size = 4069.000000 MB (4266655744 bytes) |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| import java.io.*; | |
| import java.util.*; | |
| import sun.jvm.hotspot.memory.*; | |
| import sun.jvm.hotspot.oops.*; | |
| import sun.jvm.hotspot.debugger.*; | |
| import sun.jvm.hotspot.runtime.*; | |
| import sun.jvm.hotspot.tools.*; | |
| import sun.jvm.hotspot.utilities.*; | |
| public class DirectMemorySize extends Tool { | |
| public void run() { | |
| // Ready to go with the database... | |
| try { | |
| long reservedMemory = getStaticLongFieldValue("java.nio.Bits", "reservedMemory"); | |
| long directMemory = getStaticLongFieldValue("sun.misc.VM", "directMemory"); | |
| System.out.println("NIO direct memory:"); | |
| System.out.printf(" reserved size = %fMB (%d bytes)\n", toM(reservedMemory), reservedMemory); | |
| System.out.printf(" max size = %fMB (%d bytes)\n", toM(directMemory), directMemory); | |
| } catch (AddressException e) { | |
| System.err.println("Error accessing address 0x" | |
| + Long.toHexString(e.getAddress())); | |
| e.printStackTrace(); | |
| } | |
| } | |
| public static long getStaticLongFieldValue(String className, String fieldName) { | |
| InstanceKlass klass = SystemDictionaryHelper.findInstanceKlass(className); | |
| LongField field = (LongField) klass.findField(fieldName, "J"); | |
| return field.getValue(klass); | |
| } | |
| public static double toM(long value) { | |
| return value / (1024 * 1024.0); | |
| } | |
| public String getName() { | |
| return "directMemorySize"; | |
| } | |
| public static void main(String[] args) { | |
| DirectMemorySize tool = new DirectMemorySize(); | |
| tool.start(args); | |
| tool.stop(); | |
| } | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment