org.apache.hadoop.hbase.util

Class JVM

java.lang.Object

org.apache.hadoop.hbase.util.JVM

@InterfaceAudience.Private
public class JVM
extends Object

This class is a wrapper for the implementation of com.sun.management.UnixOperatingSystemMXBean It will decide to use the sun api or its own implementation depending on the runtime (vendor) used.

Field Summary

Fields

Modifier and Type	Field and Description
private static boolean	aarch64
private static boolean	amd64
private static boolean	ibmvendor
private static int	JVM_SPEC_VERSION The Integer represent of JVM_SPEC_VERSION, for the JVM version comparison.
private static String	JVM_SPEC_VERSION_STRING The raw String of java specification version.
private static String	JVMVersion
private static boolean	linux
private static org.slf4j.Logger	LOG
private OperatingSystemMXBean	osMbean
private static boolean	windows

Constructor Summary

Constructors

Constructor and Description
JVM() Constructor.

Method Summary

Modifier and Type	Method and Description
long	getFreeMemory() Return the physical free memory (not the JVM one, as it's not very useful as it depends on the GC), but the one from the OS as it allows a little bit more to guess if the machine is overloaded or not).
static int	getJVMSpecVersion()
long	getMaxFileDescriptorCount() Get the number of the maximum file descriptors the system can use.
int	getNumberOfRunningProcess() Workaround to get the current number of process running.
long	getOpenFileDescriptorCount() Get the number of opened filed descriptor for the runtime jvm.
double	getSystemLoadAverage() Get the system load average
static boolean	isAarch64() Check if the arch is aarch64;
static boolean	isAmd64() Check if the arch is amd64;
static boolean	isGZIPOutputStreamFinishBroken() Check if the finish() method of GZIPOutputStream is broken
static boolean	isLinux() Check if the OS is linux.
static boolean	isUnix() Check if the OS is unix.
private Long	runUnixMXBeanMethod(String mBeanMethodName) Load the implementation of UnixOperatingSystemMXBean for Oracle jvm and runs the desired method.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

private static final org.slf4j.Logger LOG

osMbean

private OperatingSystemMXBean osMbean

ibmvendor

private static final boolean ibmvendor

windows

private static final boolean windows

linux

private static final boolean linux

amd64

private static final boolean amd64

aarch64

private static final boolean aarch64

JVMVersion

private static final String JVMVersion

JVM_SPEC_VERSION_STRING

private static final String JVM_SPEC_VERSION_STRING

The raw String of java specification version. "1.8" for java8, "9","10"... for Java 9, 10...

JVM_SPEC_VERSION

private static final int JVM_SPEC_VERSION

The Integer represent of JVM_SPEC_VERSION, for the JVM version comparison. Java 8, 9, 10 ... will be noted as 8, 9 10 ...

Constructor Detail

JVM

public JVM()

Constructor. Get the running Operating System instance

Method Detail

isUnix

public static boolean isUnix()

Check if the OS is unix.

Returns:

whether this is unix or not.

isLinux

public static boolean isLinux()

Check if the OS is linux.

Returns:

whether this is linux or not.

isAmd64

public static boolean isAmd64()

Check if the arch is amd64;

Returns:

whether this is amd64 or not.

isAarch64

public static boolean isAarch64()

Check if the arch is aarch64;

Returns:

whether this is aarch64 or not.

isGZIPOutputStreamFinishBroken

public static boolean isGZIPOutputStreamFinishBroken()

Check if the finish() method of GZIPOutputStream is broken

Returns:

whether GZIPOutputStream.finish() is broken.

getJVMSpecVersion

public static int getJVMSpecVersion()

runUnixMXBeanMethod

private Long runUnixMXBeanMethod(String mBeanMethodName)

Load the implementation of UnixOperatingSystemMXBean for Oracle jvm and runs the desired method.

Parameters:

mBeanMethodName - : method to run from the interface UnixOperatingSystemMXBean

Returns:

the method result

getOpenFileDescriptorCount

public long getOpenFileDescriptorCount()

Get the number of opened filed descriptor for the runtime jvm. If Oracle java, it will use the com.sun.management interfaces. Otherwise, this methods implements it (linux only).

Returns:

number of open file descriptors for the jvm

getSystemLoadAverage

public double getSystemLoadAverage()

Get the system load average

See Also:

OperatingSystemMXBean.getSystemLoadAverage()

getFreeMemory

public long getFreeMemory()

Return the physical free memory (not the JVM one, as it's not very useful as it depends on the GC), but the one from the OS as it allows a little bit more to guess if the machine is overloaded or not).

getNumberOfRunningProcess

public int getNumberOfRunningProcess()

Workaround to get the current number of process running. Approach is the one described here: http://stackoverflow.com/questions/54686/how-to-get-a-list-of-current-open-windows-process-with-java

getMaxFileDescriptorCount

public long getMaxFileDescriptorCount()

Get the number of the maximum file descriptors the system can use. If Oracle java, it will use the com.sun.management interfaces. Otherwise, this methods implements it (linux only).

Returns:

max number of file descriptors the operating system can use.