Module openj9.jvm

Package com.ibm.jvm

Class Stats

java.lang.Object

com.ibm.jvm.Stats

public class Stats
extends Object

This class is used provide the following java heap and system statistics:

• committed heap memory
• used heap memory
• max heap memory
• softmx heap memory
• free physical memory
• total physical memory

All this info is retrieved without any allocation of new objects.

Constructor Summary

Constructors

Constructor	Description
Stats()	Construct a new instance.

Method Summary

Modifier and Type	Method	Description
long	getCommittedHeap()
long	getCpuTime()	Returns total amount of time the process has been scheduled or executed so far in both kernel and user modes.
long	getFreePhysicalMem()
long	getMaxHeap()
long	getSoftmxHeap()
void	getStats()	Native method used to retrieve the heap/OS stats.
double	getSysLoadAvg()
long	getTotPhysicalMem()
long	getUsedHeap()
void	setFields(long committed, long used, long max, long free, long tot, double sysLoadAvg, long cpuTime, long softmxHeap)	To avoid allocating new objects, this function merely sets the member variables of this class as it is called from a native.

Methods declared in class java.lang.Object

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

Constructor Detail

Stats

public Stats()

Construct a new instance.

Method Detail

setFields

public void setFields(long committed,
                      long used,
                      long max,
                      long free,
                      long tot,
                      double sysLoadAvg,
                      long cpuTime,
                      long softmxHeap)

To avoid allocating new objects, this function merely sets the member variables of this class as it is called from a native.

Parameters:

committed - is the committed heap size (bytes)

used - is the amount of used memory on the java heap (bytes)

max - is the maximum bound of the java heap (bytes)

free - is the amount of free physical memory (bytes)

tot - is the amount of total physical memory (bytes)

sysLoadAvg - is the system load average in decimal (capacity of cpu)

cpuTime - is the time elapsed since the start of the jvm process

softmxHeap - is the softmx heap value (-Xsoftmx or changed from MemoryMXBean) value in bytes

getCommittedHeap

public long getCommittedHeap()

Returns:

the committed heap (reserved memory) in bytes

getUsedHeap

public long getUsedHeap()

Returns:

how much of the java heap is used by the application in bytes

getMaxHeap

public long getMaxHeap()

Returns:

the maximum java heap memory that can be used by the jvm application (-Xmx) in bytes

getSoftmxHeap

public long getSoftmxHeap()

Returns:

the softmx java heap memory (set by -Xsoftmx or from the MemoryMXBean.setMaxHeapSize)

getFreePhysicalMem

public long getFreePhysicalMem()

Returns:

the amount of free physical memory in bytes

getTotPhysicalMem

public long getTotPhysicalMem()

Returns:

the total amount of physical memory in bytes

getSysLoadAvg

public double getSysLoadAvg()

Returns:

the system load average in last minute (fraction)

getCpuTime

public long getCpuTime()

Returns total amount of time the process has been scheduled or executed so far in both kernel and user modes.

Returns:

time in 100 ns units, or -1 in the case of an error or if this metric is not supported for this operating system.

getStats

public void getStats()

Native method used to retrieve the heap/OS stats.