org.terracotta.utilities.memory

Class MemoryInfo

java.lang.Object

org.terracotta.utilities.memory.MemoryInfo

public final class MemoryInfo
extends java.lang.Object

Singleton class providing access to JVM memory information.

This class uses terminology described in the following:

• java.lang.management.MemoryMXBean
• java.lang.management.MemoryType
• java.lang.management.BufferPoolMXBean

heap memory

Java managed memory holding object instances and arrays

non-heap memory

Java managed memory holding other than object instances and arrays

direct memory

unmanaged, off-heap memory allocated using java.nio.ByteBuffer.allocateDirect

mapped memory

unmanaged, off-heap memory mapped to a region of a file created using java.nio.channels.FileChannel.map

See Also:

java.lang.management.MemoryPoolMXBean, java.lang.management.BufferPoolMXBean

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MemoryInfo.MaxDirectMemoryInfo Details of a max direct memory specification.

Method Summary

Modifier and Type	Method and Description
long	configuredMaxDirectMemory() Gets the amount of direct, off-heap memory specified using the MaxDirectMemorySize JVM option.
MemoryInfo.MaxDirectMemoryInfo	configuredMaxDirectMemoryInfo() Gets the MemoryInfo.MaxDirectMemoryInfo instance describing the max direct memory value specified by JVM option.
long	directBufferCount() Gets the number of directly allocated off-heap buffers.
long	directMemoryInUse() Gets the amount of off-heap memory in use for direct ByteBuffers.
long	effectiveMaxDirectMemory() Gets the maximum amount of direct, off-heap memory that can be used in this JVM.
MemoryInfo.MaxDirectMemoryInfo	effectiveMaxDirectMemoryInfo() Gets the MemoryInfo.MaxDirectMemoryInfo instance describing maximum amount of direct, off-heap memory that can be used in this JVM.
static java.lang.String	formatSize(long size) Formats a long memory byte-size value into a human-readable memory size.
static MemoryInfo	getInstance() Gets the singleton MemoryInfo instance.
long	heapInUse() Gets the total heap memory currently in use across all heap memory pools.
long	mappedBufferCount() Gets the number of off-heap buffers used for mapped file buffers.
long	mappedMemoryInUse() Gets the amount of off-heap memory in use for mapped ByteBuffers.
java.util.List<java.lang.management.MemoryPoolMXBean>	memoryPoolMXBeans() Gets the list of MemoryPoolMXBean instances.
long	offHeapBufferCount() Gets the number of all off-heap memory buffers in use.
long	offHeapMemoryInUse() Gets the amount of off-heap memory in use.

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static MemoryInfo getInstance()

Gets the singleton MemoryInfo instance.

Returns:

the MemoryInfo instance

effectiveMaxDirectMemory

public long effectiveMaxDirectMemory()

Gets the maximum amount of direct, off-heap memory that can be used in this JVM.

If the returned value is -1, the effectiveMaxDirectMemoryInfo() method may be used to obtain additional detail.

Returns:

the amount of off-heap memory available in this JVM; this is either the value specified using the MaxDirectMemorySize JVM option or the default calculated during JVM initialization; a value of -1 is returned if the max direct memory is unavailable

See Also:

effectiveMaxDirectMemoryInfo()

effectiveMaxDirectMemoryInfo

public MemoryInfo.MaxDirectMemoryInfo effectiveMaxDirectMemoryInfo()

Gets the MemoryInfo.MaxDirectMemoryInfo instance describing maximum amount of direct, off-heap memory that can be used in this JVM.

Returns:

the MaxDirectMemoryInfo instance for direct, off-heap memory

configuredMaxDirectMemory

public long configuredMaxDirectMemory()

Gets the amount of direct, off-heap memory specified using the MaxDirectMemorySize JVM option.

If the returned value is -1, the configuredMaxDirectMemoryInfo() method may be used to obtain additional detail.

Returns:

the amount of off-heap memory specified with the MaxDirectMemorySIze option; a value of -1 is returned if the MaxDirectMemorySize option was not specified or if the specified value could was not understood

See Also:

configuredMaxDirectMemoryInfo()

configuredMaxDirectMemoryInfo

public MemoryInfo.MaxDirectMemoryInfo configuredMaxDirectMemoryInfo()

Gets the MemoryInfo.MaxDirectMemoryInfo instance describing the max direct memory value specified by JVM option.

Returns:

the MaxDirectMemoryInfo instance describing the max direct, off-heap memory as configured by JVM option

memoryPoolMXBeans

public java.util.List<java.lang.management.MemoryPoolMXBean> memoryPoolMXBeans()

Gets the list of MemoryPoolMXBean instances.

Returns:

an immutable list of MemoryPoolMXBean instances

See Also:

java.lang.management.ManagementFactory.getMemoryPoolMXBeans

heapInUse

public long heapInUse()

Gets the total heap memory currently in use across all heap memory pools.

Returns:

the number of bytes of in-use heap memory

offHeapMemoryInUse

public long offHeapMemoryInUse()

Gets the amount of off-heap memory in use. This sum includes all off-heap memory types including direct and mapped and possibly other types depending on the JVM.

Returns:

the sum of all off-heap memory in use

offHeapBufferCount

public long offHeapBufferCount()

Gets the number of all off-heap memory buffers in use. This count includes all off-heap memory types including direct and mapped and possibly other types depending on the JVM.

Returns:

the number of off-heap buffers in use

directMemoryInUse

public long directMemoryInUse()

Gets the amount of off-heap memory in use for direct ByteBuffers.

Returns:

the amount of direct off-heap memory in use

directBufferCount

public long directBufferCount()

Gets the number of directly allocated off-heap buffers.

Returns:

the number of direct, off-heap buffers

mappedMemoryInUse

public long mappedMemoryInUse()

Gets the amount of off-heap memory in use for mapped ByteBuffers.

Returns:

the amount of mapped off-heap memory in use

mappedBufferCount

public long mappedBufferCount()

Gets the number of off-heap buffers used for mapped file buffers.

Returns:

the number of mapped buffers in use

formatSize

public static java.lang.String formatSize(long size)

Formats a long memory byte-size value into a human-readable memory size.

Parameters:

size - the memory size, in bytes, to format

Returns:

a memory size using base 2 size units

See Also:

How can I convert byte size into a human-readable format in Java?