ServerRuntimeMBean

Overview | Related MBeans | Attributes | Operations

Overview

Provides methods for retrieving runtime information about a server instance and for transitioning a server from one state to another.

Fully Qualified Interface Name	If you use the `getMBeanInfo` operation in MBeanTypeServiceMBean, supply the following value as this MBean's fully qualified interface name: `weblogic.management.runtime.ServerRuntimeMBean`
Factory Methods	No factory methods. Instances of this MBean are created automatically.

Related MBeans

This section describes attributes that provide access to other MBeans.

ApplicationRuntimes
AsyncReplicationRuntime
ClusterRuntime
ConnectorServiceRuntime
DefaultExecuteQueueRuntime
EntityCacheCumulativeRuntime
EntityCacheCurrentStateRuntime
EntityCacheHistoricalRuntime
ExecuteQueueRuntimes
JDBCServiceRuntime
JMSRuntime
JoltRuntime
JTARuntime
JVMRuntime
LibraryRuntimes
LogBroadcasterRuntime
LogRuntime
MailSessionRuntimes
MANAsyncReplicationRuntime
MANReplicationRuntime
MaxThreadsConstraintRuntimes

MessagingBridgeRuntime
MinThreadsConstraintRuntimes
PathServiceRuntime
PersistentStoreRuntimes
RequestClassRuntimes
SAFRuntime
ServerChannelRuntimes
ServerSecurityRuntime
SingleSignOnServicesRuntime
SNMPAgentRuntime
ThreadPoolRuntime
TimerRuntime
WANReplicationRuntime
WebServerRuntimes
WLDFRuntime
WorkManagerRuntimes
WseeClusterFrontEndRuntime
WseeWsrmRuntime
WTCRuntime

ApplicationRuntimes

Returns the list of currently running Applications

Lookup Operation	`lookupApplicationRuntime(String name)` Returns a `javax.management.ObjectName` for the instance of `ApplicationRuntimeMBean` named `name`.
Privileges	Read only
Type	ApplicationRuntimeMBean[]
Relationship type:	Reference.

AsyncReplicationRuntime

Return an MBean which represents this server's view of its AsyncReplicationRuntime, if any.

Privileges	Read only
Type	AsyncReplicationRuntimeMBean
Relationship type:	Reference.

ClusterRuntime

Return an MBean which represents this server's view of its cluster, if any.

Privileges	Read only
Type	ClusterRuntimeMBean
Relationship type:	Reference.

ConnectorServiceRuntime

The access point for server wide control and monitoring of the Connector Container.

Privileges	Read only
Type	ConnectorServiceRuntimeMBean
Relationship type:	Reference.

DefaultExecuteQueueRuntime

Return an MBean which exposes this server's default execute queue.

Privileges	Read only
Type	ExecuteQueueRuntimeMBean
Relationship type:	Reference.

EntityCacheCumulativeRuntime

Return an MBean which represents Cumulative Status of the XML Cache.

Privileges	Read only
Type	EntityCacheCumulativeRuntimeMBean
Relationship type:	Reference.

EntityCacheCurrentStateRuntime

Return an MBean which represents Current Status of the XML Cache.

Privileges	Read only
Type	EntityCacheCurrentStateRuntimeMBean
Relationship type:	Reference.

EntityCacheHistoricalRuntime

Return an MBean which represents Historical Status of the XML Cache.

Privileges	Read only
Type	EntityCacheCumulativeRuntimeMBean
Relationship type:	Reference.

ExecuteQueueRuntimes

Returns an array of MBeans which exposes this server's active execute queues.

Privileges	Read only
Type	ExecuteQueueRuntimeMBean[]
Relationship type:	Reference.

JDBCServiceRuntime

The JDBCServiceRuntimeMBean for this server.

Privileges	Read only
Type	JDBCServiceRuntimeMBean
Relationship type:	Reference.

JMSRuntime

The JMSRuntimeMBean for this server.

Privileges	Read only
Type	JMSRuntimeMBean
Relationship type:	Reference.

JoltRuntime

The JoltConnectionServiceRuntimeMBean for this server.

Privileges	Read only
Type	JoltConnectionServiceRuntimeMBean
Relationship type:	Reference.

JTARuntime

The transaction RuntimeMBean for this server.

For more information, see:

JTARuntimeMBean

Privileges	Read/Write
Type	JTARuntimeMBean
Relationship type:	Reference.
Redeploy or Restart required	Changes take effect after you redeploy the module or restart the server.

JVMRuntime

The JVMRuntimeMBean for this server.

For more information, see:

JVMRuntimeMBean

Privileges	Read/Write
Type	JVMRuntimeMBean
Relationship type:	Reference.
Redeploy or Restart required	Changes take effect after you redeploy the module or restart the server.

LibraryRuntimes

Returns all deployed Libraries

Lookup Operation	`lookupLibraryRuntime(String name)` Returns a `javax.management.ObjectName` for the instance of `LibraryRuntimeMBean` named `name`.
Privileges	Read only
Type	LibraryRuntimeMBean[]
Relationship type:	Reference.

LogBroadcasterRuntime

The object which generates notifications on behalf of the logging subystem.

Factory Methods	No explicit creator method. The child shares the lifecycle of its parent.
Privileges	Read only
Type	LogBroadcasterRuntimeMBean
Relationship type:	Containment.

LogRuntime

Return the MBean which provides access to the control interface for WLS server logging.

Privileges	Read only
Type	LogRuntimeMBean
Relationship type:	Reference.

MailSessionRuntimes

Return the runtimeMBeans for JavaMail Mail Sessions

Privileges	Read only
Type	MailSessionRuntimeMBean[]
Relationship type:	Reference.

MANAsyncReplicationRuntime

Return an MBean which represents this server's view of its MANAsyncReplicationRuntime, if any.

Privileges	Read only
Type	MANAsyncReplicationRuntimeMBean
Relationship type:	Reference.

MANReplicationRuntime

Return an MBean which represents this server's view of its MANReplicationRuntime, if any.

Privileges	Read only
Type	MANReplicationRuntimeMBean
Relationship type:	Reference.

MaxThreadsConstraintRuntimes

Returns an array of RuntimeMBeans which exposes this server's globally defined MaxThreadsConstraints.

Lookup Operation	`lookupMaxThreadsConstraintRuntime(String name)` Returns a `javax.management.ObjectName` for the instance of `MaxThreadsConstraintRuntimeMBean` named `name`.
Privileges	Read only
Type	MaxThreadsConstraintRuntimeMBean[]
Relationship type:	Reference.

MessagingBridgeRuntime

The MessagingBridgeRuntimeMBean for this server

Privileges	Read/Write
Type	MessagingBridgeRuntimeMBean
Relationship type:	Reference.
Redeploy or Restart required	Changes take effect after you redeploy the module or restart the server.

MinThreadsConstraintRuntimes

Returns an array of RuntimeMBeans which exposes this server's globally defined MinThreadsConstraints.

Lookup Operation	`lookupMinThreadsConstraintRuntime(String name)` Returns a `javax.management.ObjectName` for the instance of `MinThreadsConstraintRuntimeMBean` named `name`.
Privileges	Read only
Type	MinThreadsConstraintRuntimeMBean[]
Relationship type:	Reference.

PathServiceRuntime

The PathServiceRuntimeMBean for this server.

Privileges	Read only
Type	PathServiceRuntimeMBean
Relationship type:	Reference.

PersistentStoreRuntimes

Returns the mbeans that provides runtime information for each PersistentStore.

Lookup Operation	`lookupPersistentStoreRuntime(String name)` Returns a `javax.management.ObjectName` for the instance of `PersistentStoreRuntimeMBean` named `name`.
Privileges	Read only
Type	PersistentStoreRuntimeMBean[]
Relationship type:	Reference.

RequestClassRuntimes

Returns an array of RuntimeMBeans which exposes this server's globally defined Request Classes.

Lookup Operation	`lookupRequestClassRuntime(String name)` Returns a `javax.management.ObjectName` for the instance of `RequestClassRuntimeMBean` named `name`.
Privileges	Read only
Type	RequestClassRuntimeMBean[]
Relationship type:	Reference.

SAFRuntime

The SAFRuntimeMBean for this server.

Privileges	Read only
Type	SAFRuntimeMBean
Relationship type:	Reference.

ServerChannelRuntimes

The network channels that are currently configured on the server.

Factory Methods	No explicit creator method. The child shares the lifecycle of its parent.
Privileges	Read only
Type	ServerChannelRuntimeMBean[]
Relationship type:	Containment.

ServerSecurityRuntime

Return the ServerSecurityRuntimeMBean for this server.

Privileges	Read only
Type	ServerSecurityRuntimeMBean
Relationship type:	Reference.

SingleSignOnServicesRuntime

Get the runtime interface to publish single sign-on services information.

Privileges	Read only
Type	SingleSignOnServicesRuntimeMBean
Relationship type:	Reference.

SNMPAgentRuntime

Return the MBean which provides access to the monitoring statistics for WLS SNMP Agent.

Privileges	Read only
Type	SNMPAgentRuntimeMBean
Relationship type:	Reference.

ThreadPoolRuntime

Get the self-tuning thread pool's runtime information. This call will return null if the self-tuning implementation is not enabled.

Privileges	Read only
Type	ThreadPoolRuntimeMBean
Relationship type:	Reference.

TimerRuntime

Get the runtime information about the WebLogic timer implementation.

Privileges	Read only
Type	TimerRuntimeMBean
Relationship type:	Reference.

WANReplicationRuntime

Return an MBean which represents this server's view of its WANReplicationRuntime, if any.

Privileges	Read only
Type	WANReplicationRuntimeMBean
Relationship type:	Reference.

WebServerRuntimes

Returns all the initialized webservers

Privileges	Read only
Type	WebServerRuntimeMBean[]
Relationship type:	Reference.

WLDFRuntime

Return the MBean which provides access to all Diagnostic runtime MBeans.

Privileges	Read only
Type	WLDFRuntimeMBean
Relationship type:	Reference.

WorkManagerRuntimes

Returns an array of MBeans which exposes this server's active internal WorkManagers.

Privileges	Read only
Type	WorkManagerRuntimeMBean[]
Relationship type:	Reference.

WseeClusterFrontEndRuntime

This is non-null only when this server is running as a host to a front-end proxy (HttpClusterServlet) instance.

Privileges	Read only
Type	WseeClusterFrontEndRuntimeMBean
Relationship type:	Reference.

WseeWsrmRuntime

Get statistics for web services reliable messaging across the entire server if any web service is deployed that employs reliable messaging. This MBean is null otherwise.

Privileges	Read only
Type	WseeWsrmRuntimeMBean
Relationship type:	Reference.

WTCRuntime

The WTCRuntimeMBean for this server.

Privileges	Read only
Type	WTCRuntimeMBean
Relationship type:	Reference.

Attributes

This section describes the following attributes:

ActivationTime
AdministrationPort
AdministrationPortEnabled
AdministrationURL
AdminServer
AdminServerHost
AdminServerListenPort
AdminServerListenPortSecure
CachingDisabled
CurrentDirectory
CurrentMachine
DefaultURL
HealthState
ListenAddress
ListenPort
ListenPortEnabled
MBeanInfo
MiddlewareHome
Name
ObjectName

OpenSocketsCurrentCount
OracleHome
OverallHealthState
Parent
Registered
RestartRequired
RestartsTotalCount
ServerClasspath
SocketsOpenedTotalCount
SSLListenAddress
SSLListenPort
SSLListenPortEnabled
State
StateVal
Type
WeblogicHome
WeblogicVersion
WLECConnectionServiceRuntime

ActivationTime

The time when the server was started.

Privileges	Read only
Type	long

AdministrationPort

The port on which this server is listening for administrative requests.

Deprecated. 9.0.0.0 Replaced by AdministrationURL

Privileges	Read only
Type	int

AdministrationPortEnabled

Indicates whether the administration port is enabled on the server

Privileges	Read only
Type	boolean

AdministrationURL

The URL that the server and its clients use for administrative connections.

If no administration channel is enabled, then this method returns the URL for connections through the default channel. If the default channel is de-activated, this method returns the URL for a secure channel. If no secure channel is enabled, the method returns null.

The returned URL will be consistent with dynamic channel updates.

Privileges	Read only
Type	java.lang.String

AdminServer

Indicates whether the server is an Administration Server.

Privileges	Read only
Type	boolean

AdminServerHost

The address on which the Administration Server is listening for connections. For example, this might return the string: santiago

Privileges	Read only
Type	java.lang.String

AdminServerListenPort

The port on which the Administration Server is listening for connections.

Privileges	Read only
Type	int

AdminServerListenPortSecure

Indicates whether the port that the server uses for administrative traffic is configured to use a secure protocol.

Privileges	Read only
Type	boolean

CachingDisabled

Private property that disables caching in proxies.

Privileges	Read only
Type	boolean

CurrentDirectory

The absolute path of the directory from which the server was started.

This may be used in conjunction with other relative paths in ServerMBean to compute full paths.

For more information, see:

ServerMBean

Privileges	Read only
Type	java.lang.String

CurrentMachine

Return the machine on which the server is running. This will be different from the configuration if the server gets migrated automatically. * @return Machine on which server is running.

Privileges	Read/Write
Type	java.lang.String

DefaultURL

The URL that clients use to connect to this server's default network channel.

The returned value indicates the default protocol, listen address and listen port:
protocol://listen-address:listen-port

Note:: The default protocol, listen address and listen port are persisted in the domain's config.xml file, however when a server instance is started, command-line options can override these persisted values. This getDefaultURL method returns the URL values that are currently being used, not necessarily the values that are specified in config.xml.

The returned URL will be consistent with dynamic channel updates.

Privileges	Read only
Type	java.lang.String

HealthState

The health state of the server as reported by the server's self-health monitoring. See weblogic.health.HealthState for state values.

For example, the server can report if it is overloaded by too many requests, if it needs more memory resources, or if it will soon fail for other reasons.

Privileges	Read only
Type	weblogic.health.HealthState

ListenAddress

The address on which this server is listening for connections through the default network channel.

For example this might return the string: santiago/172.17.9.220.

You can configure other network channels for this server, and the other channels can use different listen addresses.

Deprecated. 9.0.0.0 Replaced by URL

For more information, see:

getServerChannel(String)

Privileges	Read only
Type	java.lang.String

ListenPort

The port on which this server is listening for connections.

Deprecated. 9.0.0.0 Replaced by URL

Privileges	Read only
Type	int

ListenPortEnabled

Indicates whether the default listen port is enabled on the server.

Privileges	Read only
Type	boolean

MBeanInfo

Returns the MBean info for this MBean.

Deprecated.

Privileges	Read only
Type	javax.management.MBeanInfo

MiddlewareHome

The Oracle Middleware installation directory.

Available Since	Release 10.3.3.0
Privileges	Read only
Type	java.lang.String

Name

The name of this configuration. WebLogic Server uses an MBean to implement and persist the configuration.

Privileges	Read only
Type	java.lang.String

ObjectName

Returns the ObjectName under which this MBean is registered in the MBean server.

Deprecated.

Privileges	Read only
Type	weblogic.management.WebLogicObjectName

OpenSocketsCurrentCount

The current number of sockets registered for socket muxing on this server.

Privileges	Read only
Type	int

OracleHome

The directory where Oracle products are installed.

Deprecated since 10.3.3

Deprecated. WLS can no longer find out what ORACLE_HOME is

Available Since	Release 10.3.1.0
Privileges	Read only
Type	java.lang.String

OverallHealthState

Determine the overall health state of this server, taking into account the health of each of its subsystems. See weblogic.health.HealthState for state values.

Privileges	Read only
Type	weblogic.health.HealthState

Parent

Return the immediate parent for this MBean

Privileges	Read/Write
Type

Registered

Returns false if the MBean represented by this object has been unregistered.

Deprecated.

Privileges	Read only
Type	boolean

RestartRequired

Indicates whether the server must be restarted in order to activate configuration changes.

Available Since	Release 9.0.0.0
Privileges	Read only
Type	boolean

RestartsTotalCount

The total number of restarts for this server since the cluster was last started.

Deprecated. This attribute always returns a value of 0. Please use ServerLifeCycleRuntimeMBean#getNodeManagerRestartCount() if the NodeManager is used to start servers

Privileges	Read only
Type	int

ServerClasspath

Get the classpath for this server including domain/lib contents that are automatically picked up and appended to the classpath.

Available Since	Release 9.0.0.0
Privileges	Read only
Type	java.lang.String

SocketsOpenedTotalCount

The total number of registrations for socket muxing on this sever.

Deprecated. Use OpenSocketsCurrentCount instead. Both methods return the same value. This method is being deprecated in favor of the other method.

Privileges	Read only
Type	long

SSLListenAddress

The address on which this server is listening for SSL connections. For example this might return the string: santiago/172.17.9.220

Deprecated. 9.0.0.0 Replaced by URL

Privileges	Read only
Type	java.lang.String

SSLListenPort

The port on which this server is listening for SSL connections.

Deprecated. 9.0.0.0 Replaced by URL

Privileges	Read only
Type	int

SSLListenPortEnabled

Indicates whether the default SSL listen port is enabled on the server

Privileges	Read only
Type	boolean

State

The current life cycle state of this server.

For example, a server can be in a RUNNING state in which it can receive and process requests or in an ADMIN state in which it can receive only administrative requests.

Privileges	Read only
Type	java.lang.String

StateVal

Returns current state of the server as in integer. ServerStates has more information about the available server states

Privileges	Read only
Type	int

Type

Returns the type of the MBean.

Privileges	Read only
Type	java.lang.String

WeblogicHome

The directory where the WebLogic Server instance (server) is installed, without the trailing "/server".

Available Since	Release 10.3.1.0
Privileges	Read only
Type	java.lang.String

WeblogicVersion

The version of this WebLogic Server instance (server).

Privileges	Read only
Type	java.lang.String

WLECConnectionServiceRuntime

The WLECConnectionServiceRuntime for this server.

Privileges	Read only
Type

Operations

This section describes the following operations:

addRequestClassRuntime
forceShutdown
forceSuspend
getIPv4URL
getIPv6URL
getServerChannel
getURL
preDeregister

restartSSLChannels
resume
shutdown
shutdown
start
suspend
suspend

addRequestClassRuntime

Operation Name	`"addRequestClassRuntime"`
Parameters	`Object [] { }` where:
Signature	`String [] { "weblogic.management.runtime.RequestClassRuntimeMBean" }`
Returns	`boolean`

forceShutdown

Force shutdown the server. Causes the server to reject new requests and fail pending requests.

Operation Name	`"forceShutdown"`
Parameters	`null`
Signature	`null`
Returns	`void`
Exceptions	`weblogic.server.ServerLifecycleException`
Security roles	Only the following roles can invoke this operation: Operator

forceSuspend

Transitions the server from RUNNING to ADMIN state forcefully cancelling inflight work.

Work that cannot be cancelled is dropped. Applications are brought into the admin mode. This is the supported way of force suspending the server and getting it into ADMIN state.

Operation Name	`"forceSuspend"`
Parameters	`null`
Signature	`null`
Returns	`void`
Exceptions	`weblogic.server.ServerLifecycleException` ServerLifecycleException server failed to force suspend. A {@link #forceShutdown()} operation can be invoked.

getIPv4URL

The URL that clients use when connecting to this server using the specified protocol.

Note:: The listen address and listen port for a given protocol are persisted in the domain's config.xml file, however when a server instance is started, command-line options can override these persisted values. This getURL method returns the URL values that are currently being used, not necessarily the values that are specified in config.xml.

Operation Name	`"getIPv4URL"`
Parameters	`Object [] { protocol }` where: `protocol` is an object of type `java.lang.String` that specifies: the desired protocol
Signature	`String [] { "java.lang.String" }`
Returns	`String`

getIPv6URL

The URL that clients use when connecting to this server using the specified protocol.

Note:: The listen address and listen port for a given protocol are persisted in the domain's config.xml file, however when a server instance is started, command-line options can override these persisted values. This getURL method returns the URL values that are currently being used, not necessarily the values that are specified in config.xml.

Operation Name	`"getIPv6URL"`
Parameters	`Object [] { protocol }` where: `protocol` is an object of type `java.lang.String` that specifies: the desired protocol
Signature	`String [] { "java.lang.String" }`
Returns	`String`

getServerChannel

The address on which this server is listening for connections that use the specified protocol.

Note:: The listen address is persisted in the domain's config.xml file, however when a server instance is started, a command-line option can override the persisted listen address. This getServerChannel method returns the listen address that is currently being used, not necessarily the address that is specified in config.xml.

The returned address will always be resolved.

Operation Name	`"getServerChannel"`
Parameters	`Object [] { protocol }` where: `protocol` is an object of type `java.lang.String` that specifies: the desired protocol
Signature	`String [] { "java.lang.String" }`
Returns	`InetSocketAddress`

getURL

The URL that clients use when connecting to this server using the specified protocol.

Note:: The listen address and listen port for a given protocol are persisted in the domain's config.xml file, however when a server instance is started, command-line options can override these persisted values. This getURL method returns the URL values that are currently being used, not necessarily the values that are specified in config.xml.

Operation Name	`"getURL"`
Parameters	`Object [] { protocol }` where: `protocol` is an object of type `java.lang.String` that specifies: the desired protocol
Signature	`String [] { "java.lang.String" }`
Returns	`String`

preDeregister

Operation Name	`"preDeregister"`
Parameters	`null`
Signature	`null`
Returns	`void`
Exceptions	`java.lang.Exception`

restartSSLChannels

Restart all SSL channels on which the server is listening. This could be necessary because of some change that the server is not aware of, for instance updates to the keystore.

Operation Name	`"restartSSLChannels"`
Parameters	`null`
Signature	`null`
Returns	`void`

resume

Resume suspended server. Allow new requests. This operation transitions the server into RUNNING state.

Operation Name	`"resume"`
Parameters	`null`
Signature	`null`
Returns	`void`
Exceptions	`weblogic.server.ServerLifecycleException`
Security roles	Only the following roles can invoke this operation: Operator

shutdown

Gracefully shuts down the server after handling inflight work; optionally ignores pending HTTP sessions while handling inflight work.

The following inflight work is allowed to complete before shutdown:

Pending transaction's and TLOG checkpoint
Pending HTTP sessions
Pending JMS work
Pending work in the execute queues
RMI requests with transaction context

Further administrative calls are accepted while the server is completing inflight work. For example a forceShutdown command can be issued to quickly shutdown the server if graceful shutdown takes a long time.

Operation Name	`"shutdown"`
Parameters	`Object [] { timeout, ignoreSessions }` where: `timeout` is an object of type `java.lang.Integer` that specifies: Number of seconds to wait before aborting inflight work and shutting down the server. `ignoreSessions` is an object of type `java.lang.Boolean` that specifies: `true` indicates ignore pending HTTP sessions during inflight work handling.
Signature	`String [] { "java.lang.Integer", "java.lang.Boolean" }`
Returns	`void`
Exceptions	`weblogic.server.ServerLifecycleException`
Security roles	Only the following roles can invoke this operation: Operator

shutdown

Gracefully shuts down the server after handling inflight work.

For more information, see:

shutdown(int, boolean)

Operation Name	`"shutdown"`
Parameters	`null`
Signature	`null`
Returns	`void`
Exceptions	`weblogic.server.ServerLifecycleException`
Security roles	Only the following roles can invoke this operation: Operator

start

Unlocks a server and enables it to receive new requests.

Servers can be locked with the java weblogic.Admin LOCK command. In a locked state, a server instance accepts only administrative logins.

Deprecated. Use suspend and resume operations instead of lock/unlock.

Operation Name	`"start"`
Parameters	`null`
Signature	`null`
Returns	`void`
Security roles	Only the following roles can invoke this operation: Operator

suspend

Suspend server. Deny new requests (except by privileged users). Allow pending requests to complete. This operation transitions the server into ADMIN state. Applications and resources are fully available to administrators in ADMIN state. But non-admin users are denied access to applications and resources

For more information, see:

suspend(int, boolean)

Operation Name	`"suspend"`
Parameters	`null`
Signature	`null`
Returns	`void`
Exceptions	`weblogic.server.ServerLifecycleException`

suspend

Transitions the server from RUNNING to ADMIN state gracefully.

Applications are in admin mode. Inflight work is completed. Applications and resources are fully available to administrators in ADMIN state. But non-admin users are denied access to applications and resources

Operation Name	`"suspend"`
Parameters	`Object [] { timeout, ignoreSessions }` where: `timeout` is an object of type `java.lang.Integer` that specifies: Seconds to wait for server to transition gracefully. The server calls forceSuspend() after timeout. `ignoreSessions` is an object of type `java.lang.Boolean` that specifies: drop inflight HTTP sessions during graceful suspend
Signature	`String [] { "java.lang.Integer", "java.lang.Boolean" }`
Returns	`void`
Exceptions	`weblogic.server.ServerLifecycleException` ServerLifecycleException server failed to suspend gracefully. A {@link #forceSuspend()} or a {@link #forceShutdown()} operation can be invoked.