public abstract class AttachProvider extends Object
An attach provider is a concrete subclass of this class that has a zero-argument constructor and implements the abstract methods specified below.
An attach provider implementation is typically tied to a Java virtual machine implementation, version, or even mode of operation. That is, a specific provider implementation will typically only be capable of attaching to a specific Java virtual machine implementation or version. For example, Oracle's JDK implementation ships with provider implementations that can only attach to Oracle's HotSpot virtual machine. In general, if an environment consists of Java virtual machines of different versions and from different vendors then there will be an attach provider implementation for each family of implementations or versions.
An attach provider is identified by its name
and type
. The name is typically, but not required to be, a name that corresponds to the VM vendor. The Oracle JDK implementation, for example, ships with attach providers that use the package name "sun" (for historical reasons). The type typically corresponds to the attach mechanism. For example, an implementation that uses the Doors inter-process communication mechanism might use the type "doors". The purpose of the name and type is to identify providers in environments where there are multiple providers installed.
AttachProvider implementations are loaded and instantiated at the first invocation of the providers
method. This method attempts to load all provider implementations that are installed on the platform.
All of the methods in this class are safe for use by multiple concurrent threads.
Modifier | Constructor | Description |
---|---|---|
protected |
Initializes a new instance of this class. |
Modifier and Type | Method | Description |
---|---|---|
VirtualMachine |
attachVirtualMachine |
Attaches to a Java virtual machine. |
abstract VirtualMachine |
attachVirtualMachine |
Attaches to a Java virtual machine. |
abstract List |
listVirtualMachines() |
Lists the Java virtual machines known to this provider. |
abstract String |
name() |
Return this provider's name. |
static List |
providers() |
Returns a list of the installed attach providers. |
abstract String |
type() |
Return this provider's type. |
protected AttachProvider()
SecurityException
- If a security manager has been installed and it denies AttachPermission
("createAttachProvider
")public abstract String name()
public abstract String type()
public abstract VirtualMachine attachVirtualMachine(String id) throws AttachNotSupportedException, IOException
A Java virtual machine is identified by an abstract identifier. The nature of this identifier is platform dependent but in many cases it will be the string representation of the process identifier (or pid).
This method parses the identifier and maps the identifier to a Java virtual machine (in an implementation dependent manner). If the identifier cannot be parsed by the provider then an AttachNotSupportedException
is thrown. Once parsed this method attempts to attach to the Java virtual machine. If the provider detects that the identifier corresponds to a Java virtual machine that does not exist, or it corresponds to a Java virtual machine that does not support the attach mechanism implemented by this provider, or it detects that the Java virtual machine is a version to which this provider cannot attach, then an AttachNotSupportedException
is thrown.
id
- The abstract identifier that identifies the Java virtual machine.SecurityException
- If a security manager has been installed and it denies AttachPermission
("attachVirtualMachine
"), or other permission required by the implementation.AttachNotSupportedException
- If the identifier cannot be parsed, or it corresponds to to a Java virtual machine that does not exist, or it corresponds to a Java virtual machine which this provider cannot attach.IOException
- If some other I/O error occursNullPointerException
- If id
is null
public VirtualMachine attachVirtualMachine(VirtualMachineDescriptor vmd) throws AttachNotSupportedException, IOException
A Java virtual machine can be described using a VirtualMachineDescriptor
. This method invokes the descriptor's provider()
method to check that it is equal to this provider. It then attempts to attach to the Java virtual machine.
vmd
- The virtual machine descriptorSecurityException
- If a security manager has been installed and it denies AttachPermission
("attachVirtualMachine
"), or other permission required by the implementation.AttachNotSupportedException
- If the descriptor's provider()
method returns a provider that is not this provider, or it does not correspond to a Java virtual machine to which this provider can attach.IOException
- If some other I/O error occursNullPointerException
- If vmd
is null
public abstract List<VirtualMachineDescriptor> listVirtualMachines()
This method returns a list of VirtualMachineDescriptor
elements. Each VirtualMachineDescriptor
describes a Java virtual machine to which this provider can potentially attach. There isn't any guarantee that invoking attachVirtualMachine
on each descriptor in the list will succeed.
public static List<AttachProvider> providers()
An AttachProvider is installed on the platform if:
system
class loader
).com.sun.tools.attach.spi.AttachProvider
in the resource directory META-INF/services
. The format of the provider configuration file is one fully-qualified class name per line. Space and tab characters surrounding each class name, as well as blank lines are ignored. The comment character is '#'
(0x23
), and on each line all characters following the first comment character are ignored. The file must be encoded in UTF-8.
AttachProvider implementations are loaded and instantiated (using the zero-arg constructor) at the first invocation of this method. The list returned by the first invocation of this method is the list of providers. Subsequent invocations of this method return a list of the same providers. The list is unmodifiable.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/jdk.attach/com/sun/tools/attach/spi/AttachProvider.html