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.

Constructor Summary

Constructors

Constructor and Description
JVM() Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
long	getFreeMemory()
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()
static boolean	isGZIPOutputStreamFinishBroken() Check if the finish() method of GZIPOutputStream is broken
static boolean	isUnix() Check if the OS is unix.

Methods inherited from class java.lang.Object

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

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.

isGZIPOutputStreamFinishBroken

public static boolean isGZIPOutputStreamFinishBroken()

Check if the finish() method of GZIPOutputStream is broken

Returns:

whether GZIPOutputStream.finish() is broken.

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()

See Also:

OperatingSystemMXBean.getSystemLoadAverage()

getFreeMemory

public long getFreeMemory()

Returns:

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.