Hystrix: Latency and Fault Tolerance for Distributed Systems

com.netflix.hystrix
Class HystrixCommandMetrics

java.lang.Object
  com.netflix.hystrix.HystrixCommandMetrics

public class HystrixCommandMetrics
extends java.lang.Object

Used by HystrixCommand to record metrics.

Nested Class Summary

static class

HystrixCommandMetrics.HealthCounts Number of requests during rolling window.

Method Summary

HystrixCommandGroupKey	getCommandGroup() HystrixCommandGroupKey of the HystrixCommand these metrics represent.
HystrixCommandKey	getCommandKey() HystrixCommandKey these metrics represent.
long	getCumulativeCount(HystrixRollingNumberEvent event) Get the cumulative count since the start of the application for the given HystrixRollingNumberEvent.
int	getCurrentConcurrentExecutionCount() Current number of concurrent executions of HystrixCommand.run();
int	getExecutionTimeMean() The mean (average) execution time (in milliseconds) for the HystrixCommand.run().
int	getExecutionTimePercentile(double percentile) Retrieve the execution time (in milliseconds) for the HystrixCommand.run() method being invoked at a given percentile.
HystrixCommandMetrics.HealthCounts	getHealthCounts() Retrieve a snapshot of total requests, error count and error percentage.
static HystrixCommandMetrics	getInstance(HystrixCommandKey key) Get the HystrixCommandMetrics instance for a given HystrixCommandKey or null if one does not exist.
static HystrixCommandMetrics	getInstance(HystrixCommandKey key, HystrixCommandGroupKey commandGroup, HystrixCommandProperties properties) Get or create the HystrixCommandMetrics instance for a given HystrixCommandKey.
static java.util.Collection<HystrixCommandMetrics>	getInstances() All registered instances of HystrixCommandMetrics
HystrixCommandProperties	getProperties() HystrixCommandProperties of the HystrixCommand these metrics represent.
long	getRollingCount(HystrixRollingNumberEvent event) Get the rolling count for the given HystrixRollingNumberEvent.
int	getTotalTimeMean() The mean (average) execution time (in milliseconds) for HystrixCommand.execute() or HystrixCommand.queue().
int	getTotalTimePercentile(double percentile) Retrieve the total end-to-end execution time (in milliseconds) for HystrixCommand.execute() or HystrixCommand.queue() at a given percentile.

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static HystrixCommandMetrics getInstance(HystrixCommandKey key,
                                                HystrixCommandGroupKey commandGroup,
                                                HystrixCommandProperties properties)

Get or create the HystrixCommandMetrics instance for a given HystrixCommandKey.

This is thread-safe and ensures only 1 HystrixCommandMetrics per HystrixCommandKey.

Parameters:

key - HystrixCommandKey of HystrixCommand instance requesting the HystrixCommandMetrics

commandGroup - Pass-thru to HystrixCommandMetrics instance on first time when constructed

properties - Pass-thru to HystrixCommandMetrics instance on first time when constructed

Returns:

HystrixCommandMetrics

getInstance

public static HystrixCommandMetrics getInstance(HystrixCommandKey key)

Get the HystrixCommandMetrics instance for a given HystrixCommandKey or null if one does not exist.

Parameters:

key - HystrixCommandKey of HystrixCommand instance requesting the HystrixCommandMetrics

Returns:

HystrixCommandMetrics

getInstances

public static java.util.Collection<HystrixCommandMetrics> getInstances()

All registered instances of HystrixCommandMetrics

Returns:

Collection<HystrixCommandMetrics>

getCommandKey

public HystrixCommandKey getCommandKey()

HystrixCommandKey these metrics represent.

Returns:

HystrixCommandKey

getCommandGroup

public HystrixCommandGroupKey getCommandGroup()

HystrixCommandGroupKey of the HystrixCommand these metrics represent.

Returns:

HystrixCommandGroupKey

getProperties

public HystrixCommandProperties getProperties()

HystrixCommandProperties of the HystrixCommand these metrics represent.

Returns:

HystrixCommandProperties

getCumulativeCount

public long getCumulativeCount(HystrixRollingNumberEvent event)

Get the cumulative count since the start of the application for the given HystrixRollingNumberEvent.

Parameters:

event - HystrixRollingNumberEvent of the event to retrieve a sum for

Returns:

long cumulative count

getRollingCount

public long getRollingCount(HystrixRollingNumberEvent event)

Get the rolling count for the given HystrixRollingNumberEvent.

The rolling window is defined by HystrixCommandProperties.metricsRollingStatisticalWindowInMilliseconds().

Parameters:

event - HystrixRollingNumberEvent of the event to retrieve a sum for

Returns:

long rolling count

getExecutionTimePercentile

public int getExecutionTimePercentile(double percentile)

Retrieve the execution time (in milliseconds) for the HystrixCommand.run() method being invoked at a given percentile.

Percentile capture and calculation is configured via HystrixCommandProperties.metricsRollingStatisticalWindowInMilliseconds() and other related properties.

Parameters:

percentile - Percentile such as 50, 99, or 99.5.

Returns:

int time in milliseconds

getExecutionTimeMean

public int getExecutionTimeMean()

The mean (average) execution time (in milliseconds) for the HystrixCommand.run().

This uses the same backing data as HystrixCommandMetrics.getExecutionTimePercentile(double);

Returns:

int time in milliseconds

getTotalTimePercentile

public int getTotalTimePercentile(double percentile)

Retrieve the total end-to-end execution time (in milliseconds) for HystrixCommand.execute() or HystrixCommand.queue() at a given percentile.

When execution is successful this would include time from HystrixCommandMetrics.getExecutionTimePercentile(double) but when execution is being rejected, short-circuited, or timed-out then the time will differ.

This time can be lower than HystrixCommandMetrics.getExecutionTimePercentile(double) when a timeout occurs and the backing thread that calls HystrixCommand.run() is still running.

When rejections or short-circuits occur then HystrixCommand.run() will not be executed and thus not contribute time to HystrixCommandMetrics.getExecutionTimePercentile(double) but time will still show up in this metric for the end-to-end time.

This metric gives visibility into the total cost of HystrixCommand execution including the overhead of queuing, executing and waiting for a thread to invoke HystrixCommand.run() .

Percentile capture and calculation is configured via HystrixCommandProperties.metricsRollingStatisticalWindowInMilliseconds() and other related properties.

Parameters:

percentile - Percentile such as 50, 99, or 99.5.

Returns:

int time in milliseconds

getTotalTimeMean

public int getTotalTimeMean()

The mean (average) execution time (in milliseconds) for HystrixCommand.execute() or HystrixCommand.queue().

This uses the same backing data as HystrixCommandMetrics.getTotalTimePercentile(double);

Returns:

int time in milliseconds

getCurrentConcurrentExecutionCount

public int getCurrentConcurrentExecutionCount()

Current number of concurrent executions of HystrixCommand.run();

Returns:

int

getHealthCounts

public HystrixCommandMetrics.HealthCounts getHealthCounts()

Retrieve a snapshot of total requests, error count and error percentage.

Returns:

HystrixCommandMetrics.HealthCounts