JVM (Apache HBase 1.2.12 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.

Field Summary

Fields
Modifier and Type	Field and Description
`private static boolean`	`amd64`
`private static boolean`	`ibmvendor`
`private static String`	`JVMVersion`
`private static boolean`	`linux`
`private static org.apache.commons.logging.Log`	`LOG`
`private OperatingSystemMXBean`	`osMbean`
`private static boolean`	`windows`

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.
`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.apache.commons.logging.Log LOG
```
  - osMbean
```
private OperatingSystemMXBean osMbean
```
  - ibmvendor
```
private static final boolean ibmvendor
```
  - windows
```
private static final boolean windows
```
  - linux
```
private static final boolean linux
```
  - JVMVersion
```
private static final String JVMVersion
```
  - amd64
```
private static final boolean amd64
```
- 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.
  - 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()
```
    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

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOG

osMbean

ibmvendor

windows

linux

JVMVersion

amd64

Constructor Detail

JVM

Method Detail

isUnix

isLinux

isAmd64

isGZIPOutputStreamFinishBroken

runUnixMXBeanMethod

getOpenFileDescriptorCount

getSystemLoadAverage

getFreeMemory

getNumberOfRunningProcess

getMaxFileDescriptorCount