Package org.apache.beam.sdk.io.components.throttling

Class AdaptiveThrottler

java.lang.Object

org.apache.beam.sdk.io.components.throttling.AdaptiveThrottler

Direct Known Subclasses:

ReactiveThrottler

public class AdaptiveThrottler
extends Object

Implements adaptive throttling.

See https://landing.google.com/sre/book/chapters/handling-overload.html#client-side-throttling-a7sYUg for a full discussion of the use case and algorithm applied.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	MIN_REQUESTS

Constructor Summary

Constructors

Constructor	Description
AdaptiveThrottler(long samplePeriodMs, long sampleUpdateMs, double overloadRatio)	Initializes AdaptiveThrottler.

Method Summary

Modifier and Type	Method	Description
void	successfulRequest(long nowMsSinceEpoch)	Notifies the throttler of a successful request.
boolean	throttleRequest(long nowMsSinceEpoch)	Determines whether one RPC attempt should be throttled.
protected double	throttlingProbability(long nowMsSinceEpoch)

Methods inherited from class java.lang.Object

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

Field Details

MIN_REQUESTS

public static final int MIN_REQUESTS

See Also:

• Constant Field Values

Constructor Details

AdaptiveThrottler

public AdaptiveThrottler(long samplePeriodMs,
 long sampleUpdateMs,
 double overloadRatio)

Initializes AdaptiveThrottler.

Parameters:

samplePeriodMs - length of history to consider, in ms, to set throttling.

sampleUpdateMs - granularity of time buckets that we store data in, in ms.

overloadRatio - the target ratio between requests sent and successful requests.

Method Details

throttlingProbability

protected double throttlingProbability(long nowMsSinceEpoch)

throttleRequest

public boolean throttleRequest(long nowMsSinceEpoch)

Determines whether one RPC attempt should be throttled.

This should be called once each time the caller intends to send an RPC; if it returns true, drop or delay that request (calling this function again after the delay).

Parameters:

nowMsSinceEpoch - time in ms since the epoch

Returns:

true if the caller should throttle or delay the request.

successfulRequest

public void successfulRequest(long nowMsSinceEpoch)

Notifies the throttler of a successful request.

Must be called once for each request (for which throttleRequest was previously called) that succeeded.

Parameters:

nowMsSinceEpoch - time in ms since the epoch