com.newrelic.agent.circuitbreaker

Class CircuitBreakerService

java.lang.Object

com.newrelic.agent.service.AbstractService

com.newrelic.agent.circuitbreaker.CircuitBreakerService

All Implemented Interfaces:

HealthDataProducer, AgentConfigListener, HarvestListener, Service

public class CircuitBreakerService
extends AbstractService
implements HarvestListener, AgentConfigListener, HealthDataProducer

The CircuitBreakerService is responsible for preventing the agent from crashing an application.

When a tracer or transaction is to be created, the breaker is first checked. If it is in a tripped state the tracer will not be created. This prevents the agent from adding overhead that would otherwise cause the application to run out of memory.

The decision to trip the breaker is a function of two things: Heap memory usage and time spent garbage collecting. When an application has low free memory and high cpu time garbage collecting, the breaker trips. The breaker will reset at the end of the harvest cycle if it is back in a good state. Every N tracers the breaker is asked if it should trip.

Some of the methods on this class run almost immediately after we enter Java code from transformed bytecode. The current thread cannot be assumed to have a TransactionActivity or a Transaction.

The default memory and gc thresholds are set in CircuitBreakerConfig.

Field Summary

Fields inherited from class com.newrelic.agent.service.AbstractService

logger

Constructor Summary

Constructors

Constructor and Description
CircuitBreakerService()

Method Summary

Modifier and Type	Method and Description
void	addRPMService(RPMService rpmService)
void	afterHarvest(java.lang.String appName) Called after the harvest.
void	beforeHarvest(java.lang.String appName, StatsEngine statsEngine) Called before the harvest.
boolean	checkAndTrip() Checks memory+gc usage and trips circuit breaker if necessary.
void	configChanged(java.lang.String appName, AgentConfig agentConfig)
static SamplingCounter	createTracerSamplerCounter()
protected void	doStart()
protected void	doStop()
boolean	isEnabled() Is the service enabled.
boolean	isTripped() Update the status if the time has come and return the status.
void	registerHealthDataChangeListener(HealthDataChangeListener listener)
void	removeRPMService(RPMService rpmService)
void	reset() Reset circuit breaker;
void	setPreviousChecksForTesting(long newGCTimeNS, long newCpuTimeNS) Only use for testing.

Methods inherited from class com.newrelic.agent.service.AbstractService

getLogger, getName, isStarted, isStartedOrStarting, isStopped, isStoppedOrStopping, start, stop

Methods inherited from class java.lang.Object

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

Constructor Detail

CircuitBreakerService

public CircuitBreakerService()

Method Detail

isEnabled

public boolean isEnabled()

Description copied from interface: Service

Is the service enabled.

Specified by:

isEnabled in interface Service

Returns:

true if the service is enabled

doStart

protected void doStart()
                throws java.lang.Exception

Specified by:

doStart in class AbstractService

Throws:

java.lang.Exception

doStop

protected void doStop()
               throws java.lang.Exception

Specified by:

doStop in class AbstractService

Throws:

java.lang.Exception

beforeHarvest

public void beforeHarvest(java.lang.String appName,
                          StatsEngine statsEngine)

Description copied from interface: HarvestListener

Called before the harvest. The service may or may not be currently connected.

Specified by:

beforeHarvest in interface HarvestListener

afterHarvest

public void afterHarvest(java.lang.String appName)

Description copied from interface: HarvestListener

Called after the harvest. The service may or may not be currently connected.

Specified by:

afterHarvest in interface HarvestListener

isTripped

public boolean isTripped()

Update the status if the time has come and return the status.

Returns:

status of the circuit breaker.

reset

public void reset()

Reset circuit breaker;

checkAndTrip

public boolean checkAndTrip()

Checks memory+gc usage and trips circuit breaker if necessary. This method is public for test purposes and should not be called by client classes in production code. To only check the current status of the circuit breaker, use isTripped() instead.

Returns:

true if the circuit breaker was tripped, false otherwise.

configChanged

public void configChanged(java.lang.String appName,
                          AgentConfig agentConfig)

Specified by:

configChanged in interface AgentConfigListener

addRPMService

public void addRPMService(RPMService rpmService)

removeRPMService

public void removeRPMService(RPMService rpmService)

setPreviousChecksForTesting

public void setPreviousChecksForTesting(long newGCTimeNS,
                                        long newCpuTimeNS)

Only use for testing.

createTracerSamplerCounter

public static SamplingCounter createTracerSamplerCounter()

registerHealthDataChangeListener

public void registerHealthDataChangeListener(HealthDataChangeListener listener)

Specified by:

registerHealthDataChangeListener in interface HealthDataProducer