com.netflix.eureka.util.batcher

Class MessageBatcher<T>

java.lang.Object

com.netflix.eureka.util.batcher.MessageBatcher<T>

public class MessageBatcher<T>
extends java.lang.Object

This class is taken from blitz4j, and slightly modified so it does not depend on bliz4j singletons.

A general purpose batcher that combines messages into batches. Callers of process don't block. Configurable parameters control the number of messages that may be queued awaiting processing, the maximum size of a batch, the maximum time a message waits to be combined with others in a batch and the size of the pool of threads that process batches.

The implementation aims to avoid congestion, by working more efficiently as load increases. As messages arrive faster, the collector executes less code and batch sizes increase (up to the configured maximum). It should be more efficient to process a batch than to process the messages individually.

The implementation works by adding the arriving messages to a queue. The collector thread takes messages from the queue and collects them into batches. When a batch is big enough or old enough, the collector passes it to the processor, which passes the batch to the target stream.

The processor maintains a thread pool. If there's more work than threads, the collector participates in processing by default, and consequently stops collecting more batches.

Field Summary

Fields

Modifier and Type	Field and Description
protected com.netflix.servo.monitor.Timer	avgBatchSizeTracer
protected com.netflix.servo.monitor.Timer	batchSyncPutTracer
protected java.util.concurrent.atomic.AtomicInteger	concurrentBatches The number of batches that are currently being processed by the target stream.
protected long	maxDelayNano
protected int	maxMessages
protected java.lang.String	name
protected java.util.concurrent.ThreadPoolExecutor	processor
protected com.netflix.servo.monitor.Timer	processTimeTracer
protected java.util.concurrent.BlockingQueue<T>	queue
protected com.netflix.servo.monitor.Counter	queueOverflowCounter
protected com.netflix.servo.monitor.Timer	queueSizeTracer
protected MessageProcessor	target
protected com.netflix.servo.monitor.Timer	threadSubmitTracer

Constructor Summary

Constructors

Constructor and Description
MessageBatcher(java.lang.String name, MessageProcessor<T> target, int maxQueueSize, long maxDelayMs, int minThreads, int maxThreads, long keepAliveTimeMs, boolean shouldRejectWhenFull)

Method Summary

Methods

Modifier and Type	Method and Description
long	getNumberAdded() Gets the statistics count of number of messages added to this batcher.
long	getNumberDropped() Gets the statistics count of number of messages dropped by this batcher.
int	getSize() The size of the the queue in which the messages are batches
boolean	isBlocking() Gets the information whether the batcher is blocking or not blocking.
boolean	isPaused()
boolean	isSpaceAvailable() Checks to see if there is space available in the queue
void	pause() Pause the collector.
void	process(java.util.List<T> objects) Processes the messages sent to the batcher.
void	process(java.util.List<T> objects, boolean sync) Processes the messages sent to the batcher.
boolean	process(T message) Processes the message sent to the batcher.
void	processSync(T message) Processes the message sent to the batcher.
void	resume() Resume the collector.
void	stop() Stops the batcher.

Methods inherited from class java.lang.Object

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

Field Detail

maxDelayNano

protected long maxDelayNano

name

protected java.lang.String name

queue

protected java.util.concurrent.BlockingQueue<T> queue

maxMessages

protected int maxMessages

processor

protected java.util.concurrent.ThreadPoolExecutor processor

target

protected MessageProcessor target

concurrentBatches

protected final java.util.concurrent.atomic.AtomicInteger concurrentBatches

The number of batches that are currently being processed by the target stream.

queueSizeTracer

protected com.netflix.servo.monitor.Timer queueSizeTracer

batchSyncPutTracer

protected com.netflix.servo.monitor.Timer batchSyncPutTracer

threadSubmitTracer

protected com.netflix.servo.monitor.Timer threadSubmitTracer

processTimeTracer

protected com.netflix.servo.monitor.Timer processTimeTracer

avgBatchSizeTracer

protected com.netflix.servo.monitor.Timer avgBatchSizeTracer

queueOverflowCounter

protected com.netflix.servo.monitor.Counter queueOverflowCounter

Constructor Detail

MessageBatcher

public MessageBatcher(java.lang.String name,
              MessageProcessor<T> target,
              int maxQueueSize,
              long maxDelayMs,
              int minThreads,
              int maxThreads,
              long keepAliveTimeMs,
              boolean shouldRejectWhenFull)

Method Detail

isSpaceAvailable

public boolean isSpaceAvailable()

Checks to see if there is space available in the queue

Returns:

- true, if available false otherwise

process

public boolean process(T message)

Processes the message sent to the batcher. This method just writes the message to the queue and returns immediately. If the queue is full, the messages are dropped immediately and corresponding counter is incremented.

Parameters:

message - - The message to be processed

Returns:

boolean - true if the message is queued for processing,false(this could happen if the queue is full) otherwise

processSync

public void processSync(T message)

Processes the message sent to the batcher. This method tries to write to the queue. If the queue is full, the send blocks and waits for the available space.

Parameters:

message - - The message to be processed

process

public void process(java.util.List<T> objects)

Processes the messages sent to the batcher. This method just writes the message to the queue and returns immediately. If the queue is full, the messages are dropped immediately and corresponding counter is incremented.

Parameters:

objects - - The messages to be processed

process

public void process(java.util.List<T> objects,
           boolean sync)

Processes the messages sent to the batcher. The messages are first queued and then will be processed by the com.netflix.logging.messaging.MessageProcessor

Parameters:

objects - - The messages to be processed

sync - - if true, waits for the queue to make space, if false returns immediately after dropping the message

pause

public void pause()

Pause the collector. The collector stops picking up messages from the queue.

isPaused

public boolean isPaused()

resume

public void resume()

Resume the collector. The collector resumes picking up messages from the queue and calling the processors.

stop

public void stop()

Stops the batcher. The Batcher has to wait for the other processes like the Collector and the Executor to complete. It waits until it is notified that the other processes have completed gracefully. The collector waits until there are no more messages in the queue(tries 3 times waiting for 0.5 seconds each) and then shuts down gracefully.

getSize

@Monitor(name="batcherQueueSize",
         type=GAUGE)
public int getSize()

The size of the the queue in which the messages are batches

getNumberAdded

@Monitor(name="numberAdded",
         type=GAUGE)
public long getNumberAdded()

Gets the statistics count of number of messages added to this batcher.

getNumberDropped

@Monitor(name="numberDropped",
         type=GAUGE)
public long getNumberDropped()

Gets the statistics count of number of messages dropped by this batcher.

isBlocking

@Monitor(name="blocking",
         type=INFORMATIONAL)
public boolean isBlocking()

Gets the information whether the batcher is blocking or not blocking. By default, the batcher is non-blocking and the messages are just dropped if the queue is full. If the batcher is made blocking, the sends block and wait indefinitely until space is made in the batcher.

Returns:

- true if blocking, false otherwise