org.eclipse.jetty.server

Class LowResourceMonitor

java.lang.Object

org.eclipse.jetty.util.component.AbstractLifeCycle

org.eclipse.jetty.server.LowResourceMonitor

All Implemented Interfaces:

LifeCycle

@ManagedObject(value="Monitor for low resource conditions and activate a low resource mode if detected")
public class LowResourceMonitor
extends AbstractLifeCycle

A monitor for low resources

An instance of this class will monitor all the connectors of a server (or a set of connectors configured with setMonitoredConnectors(Collection)) for a low resources state. Low resources can be detected by:

• ThreadPool.isLowOnThreads() if Connector.getExecutor() is an instance of ThreadPool and setMonitorThreads(boolean) is true.
• If setMaxMemory(long) is non zero then low resources is detected if the JVMs Runtime instance has Runtime.totalMemory() minus Runtime.freeMemory() greater than getMaxMemory()
• If setMaxConnections(int) is non zero then low resources is dected if the total number of connections exceeds getMaxConnections()

Once low resources state is detected, the cause is logged and all existing connections returned by Connector.getConnectedEndPoints() have EndPoint.setIdleTimeout(long) set to getLowResourcesIdleTimeout(). New connections are not affected, however if the low resources state persists for more than getMaxLowResourcesTime(), then the getLowResourcesIdleTimeout() to all connections again. Once the low resources state is cleared, the idle timeout is reset to the connector default given by Connector.getIdleTimeout().

Nested Class Summary

Nested classes/interfaces inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle

AbstractLifeCycle.AbstractLifeCycleListener

Nested classes/interfaces inherited from interface org.eclipse.jetty.util.component.LifeCycle

LifeCycle.Listener

Field Summary

Fields inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle

FAILED, RUNNING, STARTED, STARTING, STOPPED, STOPPING

Constructor Summary

Constructors

Constructor and Description
LowResourceMonitor(Server server)

Method Summary

Methods

Modifier and Type	Method and Description
protected void	clearLowResources()
protected void	doStart()
protected void	doStop()
int	getLowResourcesIdleTimeout()
String	getLowResourcesReasons()
long	getLowResourcesStarted()
int	getMaxConnections()
int	getMaxLowResourcesTime()
long	getMaxMemory()
Collection<Connector>	getMonitoredConnectors()
protected Connector[]	getMonitoredOrServerConnectors()
boolean	getMonitorThreads()
int	getPeriod()
boolean	isLowOnResources()
protected void	monitor()
protected void	setLowResources()
void	setLowResourcesIdleTimeout(int lowResourcesIdleTimeoutMS)
void	setMaxConnections(int maxConnections)
void	setMaxLowResourcesTime(int maxLowResourcesTimeMS)
void	setMaxMemory(long maxMemoryBytes)
void	setMonitoredConnectors(Collection<Connector> monitoredConnectors)
void	setMonitorThreads(boolean monitorThreads)
void	setPeriod(int periodMS)

Methods inherited from class org.eclipse.jetty.util.component.AbstractLifeCycle

addLifeCycleListener, getState, getState, getStopTimeout, isFailed, isRunning, isStarted, isStarting, isStopped, isStopping, removeLifeCycleListener, setStopTimeout, start, stop

Methods inherited from class java.lang.Object

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

Constructor Detail

LowResourceMonitor

public LowResourceMonitor(@Name(value="server")
                  Server server)

Method Detail

isLowOnResources

@ManagedAttribute(value="Are the monitored connectors low on resources?")
public boolean isLowOnResources()

getLowResourcesReasons

@ManagedAttribute(value="The reason(s) the monitored connectors are low on resources")
public String getLowResourcesReasons()

getLowResourcesStarted

@ManagedAttribute(value="Get the timestamp in ms since epoch that low resources state started")
public long getLowResourcesStarted()

getMonitoredConnectors

@ManagedAttribute(value="The monitored connectors. If null then all server connectors are monitored")
public Collection<Connector> getMonitoredConnectors()

setMonitoredConnectors

public void setMonitoredConnectors(Collection<Connector> monitoredConnectors)

Parameters:

monitoredConnectors - The collections of Connectors that should be monitored for low resources.

getPeriod

@ManagedAttribute(value="The monitor period in ms")
public int getPeriod()

setPeriod

public void setPeriod(int periodMS)

Parameters:

periodMS - The period in ms to monitor for low resources

getMonitorThreads

@ManagedAttribute(value="True if low available threads status is monitored")
public boolean getMonitorThreads()

setMonitorThreads

public void setMonitorThreads(boolean monitorThreads)

Parameters:

monitorThreads - If true, check connectors executors to see if they are ThreadPool instances that are low on threads.

getMaxConnections

@ManagedAttribute(value="The maximum connections allowed for the monitored connectors before low resource handling is activated")
public int getMaxConnections()

setMaxConnections

public void setMaxConnections(int maxConnections)

Parameters:

maxConnections - The maximum connections before low resources state is triggered

getMaxMemory

@ManagedAttribute(value="The maximum memory (in bytes) that can be used before low resources is triggered.  Memory used is calculated as (totalMemory-freeMemory).")
public long getMaxMemory()

setMaxMemory

public void setMaxMemory(long maxMemoryBytes)

Parameters:

maxMemoryBytes - The maximum memory in bytes in use before low resources is triggered.

getLowResourcesIdleTimeout

@ManagedAttribute(value="The idletimeout in ms to apply to all existing connections when low resources is detected")
public int getLowResourcesIdleTimeout()

setLowResourcesIdleTimeout

public void setLowResourcesIdleTimeout(int lowResourcesIdleTimeoutMS)

Parameters:

lowResourcesIdleTimeoutMS - The timeout in ms to apply to EndPoints when in the low resources state.

getMaxLowResourcesTime

@ManagedAttribute(value="The maximum time in ms that low resources condition can persist before lowResourcesIdleTimeout is applied to new connections as well as existing connections")
public int getMaxLowResourcesTime()

setMaxLowResourcesTime

public void setMaxLowResourcesTime(int maxLowResourcesTimeMS)

Parameters:

maxLowResourcesTimeMS - The time in milliseconds that a low resource state can persist before the low resource idle timeout is reapplied to all connections

doStart

protected void doStart()
                throws Exception

Overrides:

doStart in class AbstractLifeCycle

Throws:

Exception

doStop

protected void doStop()
               throws Exception

Overrides:

doStop in class AbstractLifeCycle

Throws:

Exception

getMonitoredOrServerConnectors

protected Connector[] getMonitoredOrServerConnectors()

monitor

protected void monitor()

setLowResources

protected void setLowResources()

clearLowResources

protected void clearLowResources()