JVM (Apache HBase 1.4.11 API)

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.

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`	`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.

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.
  - 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.
  - 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.

Class JVM

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

JVM

Method Detail

isUnix

isLinux

isAmd64

isGZIPOutputStreamFinishBroken

getOpenFileDescriptorCount

getSystemLoadAverage

getFreeMemory

getNumberOfRunningProcess

getMaxFileDescriptorCount