Mirror
, ObjectReference
, Value
public interface ThreadReference extends ObjectReference
ObjectReference
with additional access to thread-specific information from the target VM.Modifier and Type | Field | Description |
---|---|---|
static final int |
THREAD_STATUS_MONITOR |
Thread is waiting on a java monitor |
static final int |
THREAD_STATUS_NOT_STARTED |
Thread has not yet been started |
static final int |
THREAD_STATUS_RUNNING |
Thread is runnable |
static final int |
THREAD_STATUS_SLEEPING |
Thread is sleeping - Thread.sleep(long) . |
static final int |
THREAD_STATUS_UNKNOWN |
Thread status is unknown |
static final int |
THREAD_STATUS_WAIT |
Thread is waiting - Object.wait() or LockSupport.park() . |
static final int |
THREAD_STATUS_ZOMBIE |
Thread has completed execution |
INVOKE_NONVIRTUAL, INVOKE_SINGLE_THREADED
Modifier and Type | Method | Description |
---|---|---|
ObjectReference |
currentContendedMonitor() |
Returns an ObjectReference for the monitor, if any, for which this thread is currently waiting. |
void |
forceEarlyReturn |
Force a method to return before it reaches a return statement. |
StackFrame |
frame |
Returns the StackFrame at the given index in the thread's current call stack. |
int |
frameCount() |
Returns the number of stack frames in the thread's current call stack. |
List |
frames() |
Returns a List containing each StackFrame in the thread's current call stack. |
List |
frames |
Returns a List containing a range of StackFrame mirrors from the thread's current call stack. |
void |
interrupt() |
Interrupts this thread unless the thread has been suspended by the debugger. |
boolean |
isAtBreakpoint() |
Determines whether the thread is suspended at a breakpoint. |
boolean |
isSuspended() |
Determines whether the thread has been suspended by the the debugger. |
default boolean |
isVirtual() |
Returns true if the thread is a virtual thread. |
String |
name() |
Returns the name of this thread. |
List |
ownedMonitors() |
Returns a List containing an ObjectReference for each monitor owned by the thread. |
List |
ownedMonitorsAndFrames() |
Returns a List containing a MonitorInfo object for each monitor owned by the thread. |
void |
popFrames |
Pop stack frames. |
void |
resume() |
Resumes this thread. |
int |
status() |
Returns the thread's status. |
void |
stop |
Stops this thread with an asynchronous exception. |
void |
suspend() |
Suspends this thread. |
int |
suspendCount() |
Returns the number of pending suspends for this thread. |
ThreadGroupReference |
threadGroup() |
Returns this thread's thread group. |
toString, virtualMachine
disableCollection, enableCollection, entryCount, equals, getValue, getValues, hashCode, invokeMethod, isCollected, owningThread, referenceType, referringObjects, setValue, uniqueID, waitingThreads
static final int THREAD_STATUS_UNKNOWN
static final int THREAD_STATUS_ZOMBIE
static final int THREAD_STATUS_RUNNING
static final int THREAD_STATUS_SLEEPING
Thread.sleep(long)
.static final int THREAD_STATUS_MONITOR
static final int THREAD_STATUS_WAIT
Object.wait()
or LockSupport.park()
. A virtual thread that is sleeping in Thread.sleep(long)
may have this thread status instead of THREAD_STATUS_SLEEPING
.static final int THREAD_STATUS_NOT_STARTED
String name()
void suspend()
resume()
or resumed with other threads through VirtualMachine.resume()
. Suspends of both the virtual machine and individual threads are counted. Before a thread will run again, it must be resumed (through resume()
or VirtualMachine.resume()
) the same number of times it has been suspended.
Suspending single threads with this method is inherently deadlock-prone. If the suspended thread holds a monitor needed by another running thread, deadlock is possible in the target VM (at least until the suspended thread is resumed again).
The suspended thread is guaranteed to remain suspended until resumed through one of the JDI resume methods mentioned above.
VMCannotBeModifiedException
- if the VirtualMachine is read-onlyvoid resume()
suspend()
or through VirtualMachine.suspend()
, or because of a SUSPEND_ALL or SUSPEND_EVENT_THREAD event, then invoking this method has no effect. Otherwise, the count of pending suspends on this thread is decremented. If it is decremented to 0, the thread will continue to execute. Note: the normal way to resume from an event related suspension is via EventSet.resume()
.VMCannotBeModifiedException
- if the VirtualMachine is read-onlyint suspendCount()
suspend()
for an explanation of counted suspends.void stop(ObjectReference throwable) throws InvalidTypeException
Throwable
object. This method may be used to send an asynchronous exception to a virtual thread when it is suspended at an event. An implementation may support sending an asynchronous exception to a suspended virtual thread in other cases.
throwable
- the asynchronous exception to throwInvalidTypeException
- if throwable
is not an instance of java.lang.Throwable in the target VMIllegalThreadStateException
- if the thread has terminated, or if the thread is a virtual thread and was not suspendedOpaqueFrameException
- if the thread is a suspended virtual thread and the implementation was unable to throw an asynchronous exception from the thread's current frameVMCannotBeModifiedException
- if the VirtualMachine is read-onlyvoid interrupt()
VMCannotBeModifiedException
- if the VirtualMachine is read-onlyint status()
THREAD_STATUS_UNKNOWN
if this information is not available. isSuspended()
can be used to determine if the thread has been suspended.boolean isSuspended()
true
if the thread is currently suspended; false
otherwise.boolean isAtBreakpoint()
true
if the thread is currently stopped at a breakpoint; false
otherwise.ThreadGroupReference threadGroup()
ThreadGroupReference
that mirrors this thread's thread group in the target VM.int frameCount() throws IncompatibleThreadStateException
IncompatibleThreadStateException
- if the thread is not suspended in the target VMList<StackFrame> frames() throws IncompatibleThreadStateException
StackFrame
in the thread's current call stack. The thread must be suspended (normally through an interruption to the VM) to get this information, and it is only valid until the thread is resumed again.StackFrame
with the current frame first followed by each caller's frame.IncompatibleThreadStateException
- if the thread is not suspended in the target VMStackFrame frame(int index) throws IncompatibleThreadStateException
StackFrame
at the given index in the thread's current call stack. Index 0 retrieves the current frame; higher indices retrieve caller frames. The thread must be suspended (normally through an interruption to the VM) to get this information, and it is only valid until the thread is resumed again.index
- the desired frameStackFrame
IncompatibleThreadStateException
- if the thread is not suspended in the target VMIndexOutOfBoundsException
- if the index is greater than or equal to frameCount()
or is negative.List<StackFrame> frames(int start, int length) throws IncompatibleThreadStateException
StackFrame
mirrors from the thread's current call stack. The thread must be suspended (normally through an interruption to the VM) to get this information, and it is only valid until the thread is resumed again.start
- the index of the first frame to retrieve. Index 0 represents the current frame.length
- the number of frames to retrieveStackFrame
with the current frame first followed by each caller's frame.IncompatibleThreadStateException
- if the thread is not suspended in the target VMIndexOutOfBoundsException
- if the specified range is not within the range of stack frame indices. That is, the exception is thrown if any of the following are true: start < 0 start >=frameCount()
length < 0 (start+length) >frameCount()
List<ObjectReference> ownedMonitors() throws IncompatibleThreadStateException
ObjectReference
for each monitor owned by the thread. A monitor is owned by a thread if it has been entered (via the synchronized statement or entry into a synchronized method) and has not been relinquished through Object.wait()
. Not all target virtual machines support this operation. Use VirtualMachine.canGetOwnedMonitorInfo()
to determine if the operation is supported.
ObjectReference
objects. The list has zero length if no monitors are owned by this thread.UnsupportedOperationException
- if the target virtual machine does not support this operation.IncompatibleThreadStateException
- if the thread is not suspended in the target VMList<MonitorInfo> ownedMonitorsAndFrames() throws IncompatibleThreadStateException
MonitorInfo
object for each monitor owned by the thread. A monitor is owned by a thread if it has been entered (via the synchronized statement or entry into a synchronized method) and has not been relinquished through Object.wait()
. Not all target virtual machines support this operation. Use VirtualMachine.canGetMonitorFrameInfo()
to determine if the operation is supported.
MonitorInfo
objects. The list has zero length if no monitors are owned by this thread.UnsupportedOperationException
- if the target virtual machine does not support this operation.IncompatibleThreadStateException
- if the thread is not suspended in the target VMObjectReference currentContendedMonitor() throws IncompatibleThreadStateException
ObjectReference
for the monitor, if any, for which this thread is currently waiting. The thread can be waiting for a monitor through entry into a synchronized method, the synchronized statement, or Object.wait()
. The status()
method can be used to differentiate between the first two cases and the third. Not all target virtual machines support this operation. Use VirtualMachine.canGetCurrentContendedMonitor()
to determine if the operation is supported.
ObjectReference
corresponding to the contended monitor, or null if it is not waiting for a monitor.UnsupportedOperationException
- if the target virtual machine does not support this operation.IncompatibleThreadStateException
- if the thread is not suspended in the target VMvoid popFrames(StackFrame frame) throws IncompatibleThreadStateException
All frames up to and including the frame
are popped off the stack. The frame previous to the parameter frame
will become the current frame.
After this operation, this thread will be suspended at the invoke instruction of the target method that created frame
. The frame
's method can be reentered with a step into the instruction.
The operand stack is restored, however, any changes to the arguments that occurred in the called method, remain. For example, if the method foo
:
void foo(int x) { System.out.println("Foo: " + x); x = 4; System.out.println("pop here"); }was called with
foo(7)
and foo
is popped at the second println
and resumed, it will print: Foo: 4
. Locks acquired by a popped frame are released when it is popped. This applies to synchronized methods that are popped, and to any synchronized blocks within them.
Finally blocks are not executed.
No aspect of state, other than this thread's execution point and locks, is affected by this call. Specifically, the values of fields are unchanged, as are external resources such as I/O streams. Additionally, the target program might be placed in a state that is impossible with normal program flow; for example, order of lock acquisition might be perturbed. Thus the target program may proceed differently than the user would expect.
This thread must be suspended.
All StackFrame
objects for this thread are invalidated.
This method may be used to pop frames of a virtual thread when it is suspended at an event. An implementation may support popping the frames of a suspended virtual thread in other cases.
No events are generated by this method.
None of the frames through and including the frame for the caller of frame may be native.
Not all target virtual machines support this operation. Use VirtualMachine.canPopFrames()
to determine if the operation is supported.
frame
- Stack frame to pop. frame
is on this thread's call stack.UnsupportedOperationException
- if the target virtual machine does not support this operation - see VirtualMachine.canPopFrames()
.IncompatibleThreadStateException
- if this thread is not suspended.IllegalArgumentException
- if frame
is not on this thread's call stack.OpaqueFrameException
- if this thread is a suspended virtual thread and the target VM was unable to pop the frames.NativeMethodException
- if one of the frames that would be popped is that of a native method or if the frame previous to frame is native.InvalidStackFrameException
- if frame
has become invalid. Once this thread is resumed, the stack frame is no longer valid. This exception is also thrown if there are no more frames.VMCannotBeModifiedException
- if the VirtualMachine is read-only.void forceEarlyReturn(Value value) throws InvalidTypeException, ClassNotLoadedException, IncompatibleThreadStateException
The method which will return early is referred to as the called method. The called method is the current method (as defined by the Frames section in the Java Virtual Machine Specification) for the specified thread at the time this method is called.
The thread must be suspended. The return occurs when execution of Java programming language code is resumed on this thread. Between the call to this method and resumption of thread execution, the state of the stack is undefined.
This method may be used to force a return from the current frame of a virtual thread when it is suspended at an event. An implementation may support forcing a return from the current frame of a suspended virtual thread in other cases.
No further instructions are executed in the called method. Specifically, finally blocks are not executed. Note: this can cause inconsistent states in the application.
A lock acquired by calling the called method (if it is a synchronized method) and locks acquired by entering synchronized blocks within the called method are released. Note: this does not apply to native locks or java.util.concurrent.locks locks.
Events, such as MethodExit, are generated as they would be in a normal return.
The called method must be a non-native Java programming language method. Forcing return on a thread with only one frame on the stack causes the thread to exit when resumed.
The value
argument is the value that the method is to return. If the return type of the method is void, then value must be a VoidValue
. Object values must be assignment compatible with the method return type (This implies that the method return type must be loaded through the enclosing class's class loader). Primitive values must be either assignment compatible with the method return type or must be convertible to the variable type without loss of information. See JLS section 5.2 for more information on assignment compatibility.
Not all target virtual machines support this operation. Use VirtualMachine.canForceEarlyReturn()
to determine if the operation is supported.
value
- the value the method is to return.UnsupportedOperationException
- if the target virtual machine does not support this operation - see canForceEarlyReturn()
IncompatibleThreadStateException
- if this thread is not suspended.OpaqueFrameException
- if this thread is a suspended virtual thread and the target VM is unable to force the method to return.NativeMethodException
- if the frame to be returned from is that of a native method.InvalidStackFrameException
- if there are no frames.InvalidTypeException
- if the value's type does not match the method's return type.ClassNotLoadedException
- if the method's return type has not yet been loaded through the appropriate class loader.VMCannotBeModifiedException
- if the VirtualMachine is read-only.default boolean isVirtual()
true
if the thread is a virtual thread.UnsupportedOperationException
.
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https://docs.oracle.com/en/java/javase/21/docs/api/jdk.jdi/com/sun/jdi/ThreadReference.html