Module openj9.dtfj

Package com.ibm.dtfj.java

Interface JavaRuntime

All Superinterfaces:

ManagedRuntime

All Known Implementing Classes:

DTFJJavaRuntime, JavaRuntime, JCJavaRuntime

public interface JavaRuntime
extends ManagedRuntime

Represents a Java runtime.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object obj)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
Iterator	getCompiledMethods()	This is short cut method.
Iterator	getHeapRoots()	Get the set of object and class roots known to the VM.
Iterator	getHeaps()	Get the set of heaps known by the VM
Iterator	getJavaClassLoaders()	Get the set of class loaders active in this VM
ImagePointer	getJavaVM()	Get the object that represents the virtual machine
JavaVMInitArgs	getJavaVMInitArgs()	Fetch the JavaVMInitArgs which were used to create this VM.
Properties	getJITProperties()	Get any vendor specific properties in use by the JIT for this Java runtime
Iterator	getMemoryCategories()	Returns iterator of the top-level memory categories used by this Java runtime.
Iterator	getMemorySections(boolean includeFreed)	Returns an iterator of JavaRuntimeMemorySection objects corresponding to the blocks of memory allocated by the JavaRuntime.
Iterator	getMonitors()	Provides access to the collection of monitors used in the JavaVM.
JavaObject	getObjectAtAddress(ImagePointer address)	Gets the object located at address address in the heap.
long	getStartTime()	Get the time when the JVM was started.
long	getStartTimeNanos()	Get the value of the JVM's high-resolution timer when the JVM was started.
default String	getSystemProperty(String key)	Get a system property of the virtual machine.
Iterator	getThreads()	Get the set of Java threads known by the VM
Object	getTraceBuffer(String bufferName, boolean formatted)	Fetches implementation specific trace buffers, like the verbose GC buffer or the Universal Trace Engine (UTE) buffer
int	hashCode()	Answers an integer hash code for the receiver.
boolean	isJITEnabled()	Determine if the JIT was enabled for this Java runtime.

Methods declared in interface com.ibm.dtfj.runtime.ManagedRuntime

getFullVersion, getVersion

Method Details

getJavaVM

ImagePointer getJavaVM()
                throws CorruptDataException

Get the object that represents the virtual machine

Returns:

the address of the JavaVM structure which represents this JVM instance in JNI

Throws:

CorruptDataException

getSystemProperty

default String getSystemProperty(String key)
                          throws DataUnavailable,
CorruptDataException

Get a system property of the virtual machine.

Parameters:

key - the name of the property to retrieve

Returns:

the value of the requested system property from this VM

Throws:

DataUnavailable - if the system properties are not available

CorruptDataException

getJavaVMInitArgs

JavaVMInitArgs getJavaVMInitArgs()
                          throws DataUnavailable,
CorruptDataException

Fetch the JavaVMInitArgs which were used to create this VM. See JNI_CreateJavaVM in the JNI Specification for more details.

Returns:

the JavaVMInitArgs which were used to create this VM.

Throws:

DataUnavailable - if the arguments are not available

CorruptDataException

getJavaClassLoaders

Iterator getJavaClassLoaders()

Get the set of class loaders active in this VM

Returns:

an iterator of all of the class loaders within this JavaVM

See Also:

• JavaClassLoader
• CorruptData

getThreads

Iterator getThreads()

Get the set of Java threads known by the VM

Returns:

an iterator of the JavaThreads in the runtime

See Also:

• JavaThread
• CorruptData

getCompiledMethods

Iterator getCompiledMethods()

This is short cut method. The same result can be found by iterating over all methods in all class loaders in all classes.

Returns:

an iterator over all of the JavaMethods in the JavaRuntime which have been compiled

See Also:

• JavaMethod
• CorruptData

getMonitors

Iterator getMonitors()

Provides access to the collection of monitors used in the JavaVM. This collection includes both monitors associated with managed objects (e.g. object monitors) and monitors associated with internal control structures (e.g. raw monitors)

Returns:

an iterator over the collection of monitors

See Also:

• JavaMonitor
• CorruptData

getHeaps

Iterator getHeaps()

Get the set of heaps known by the VM

Returns:

an iterator for all of the Java heaps within this runtime. Heaps may be specific to this JavaVM instance, or may be shared between multiple JavaVM instances

See Also:

• JavaHeap
• CorruptData

getHeapRoots

Iterator getHeapRoots()

Get the set of object and class roots known to the VM. Stack frame roots are not included in the set, they can be retrieved using JavaStackFrame.getHeapRoots().

Returns:

an iterator over the collection of JavaReferences representing the known global heap roots within this runtime.

See Also:

• JavaReference
• JavaStackFrame
• CorruptData

getTraceBuffer

Object getTraceBuffer(String bufferName,
 boolean formatted)
               throws CorruptDataException

Fetches implementation specific trace buffers, like the verbose GC buffer or the Universal Trace Engine (UTE) buffer

Parameters:

bufferName - a String naming the buffer to be fetched

formatted - true if formatting should be performed on the buffer, or false if the raw buffer contents should be returned

Returns:

an implementation specific result, depending on the parameters

Throws:

CorruptDataException

getObjectAtAddress

JavaObject getObjectAtAddress(ImagePointer address)
                       throws CorruptDataException,
IllegalArgumentException,
MemoryAccessException,
DataUnavailable

Gets the object located at address address in the heap.

Parameters:

address - the ImagePointer instance representing the start address of object in the heap;

Returns:

the JavaObject instance representing the located object.

Throws:

IllegalArgumentException - if address is outside the heap's boundaries, or if it doesn't point to the start location of an object;

MemoryAccessException - if address is in the heap but it's not accessible from the dump;

CorruptDataException - if any data needed to build the returned instance of JavaObject is corrupt.

DataUnavailable - if any data needed to build the returned instance of JavaObject is not available.

See Also:

• JavaObject

getMemoryCategories

Iterator getMemoryCategories()
                      throws DataUnavailable

Returns iterator of the top-level memory categories used by this Java runtime.

Returns:

Iterator of memory categories

Throws:

DataUnavailable

Since:

1.5

See Also:

• CorruptData

getMemorySections

Iterator getMemorySections(boolean includeFreed)
                    throws DataUnavailable

Returns an iterator of JavaRuntimeMemorySection objects corresponding to the blocks of memory allocated by the JavaRuntime.

Parameters:

includeFreed - If true, iterator will iterate over blocks of memory that have been freed, but haven't been re-used yet.

Returns:

Iterator of memory sections.

Throws:

DataUnavailable

Since:

1.5

See Also:

• CorruptData

equals

boolean equals(Object obj)

Description copied from class: java.lang.Object

Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison. The implementation in Object answers true only if the argument is the exact same object as the receiver (==).

Overrides:

equals in class Object

Parameters:

obj -

Returns:

True if the given object refers to the same Java Runtime in the image

See Also:

• Object.hashCode()

hashCode

int hashCode()

Description copied from class: java.lang.Object

Answers an integer hash code for the receiver. Any two objects which answer true when passed to .equals must answer the same value for this method.

Overrides:

hashCode in class Object

Returns:

the receiver's hash.

See Also:

• Object.equals(java.lang.Object)

isJITEnabled

boolean isJITEnabled()
              throws DataUnavailable,
CorruptDataException

Determine if the JIT was enabled for this Java runtime.

Returns:

true if the JIT was enabled, false if not

Throws:

DataUnavailable - if it is not possible to determine the JIT status

CorruptDataException

Since:

1.8

getJITProperties

Properties getJITProperties()
                     throws DataUnavailable,
CorruptDataException

Get any vendor specific properties in use by the JIT for this Java runtime

Returns:

the set of properties, which may be empty if none were set.

Throws:

DataUnavailable - if the JIT was not enabled for this runtime

CorruptDataException

Since:

1.8

getStartTime

long getStartTime()
           throws DataUnavailable,
CorruptDataException

Get the time when the JVM was started.

Returns:

the time the JVM was started, in milliseconds since 1970

Throws:

DataUnavailable - if the JVM start time is not available

CorruptDataException - if the JVM start time is corrupted

Since:

1.12

getStartTimeNanos

long getStartTimeNanos()
                throws DataUnavailable,
CorruptDataException

Get the value of the JVM's high-resolution timer when the JVM was started.

Returns:

the value of the high-resolution timer when the JVM was started, in nanoseconds

Throws:

DataUnavailable - if the JVM start time is not available

CorruptDataException - if the JVM start time is corrupted

Since:

1.12