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  4. Recommended Parameter Settings for Kafka Clients

Recommended Parameter Settings for Kafka Clients

Table 1 Producer parameters

Parameter

Default Value

Recommended Value

Description

acks

1

all (if high reliability mode is selected)

1 (if high throughput mode is selected)

Indicates the number of acknowledgments the producer requires the server to return before considering a request complete. This controls the durability of records that are sent.

Options:

0: The producer will not wait for any acknowledgment from the server at all. The record will be immediately added to the socket buffer and considered sent. No guarantee can be made that the server has received the record, and the retries configuration will not take effect (as the client generally does not know of any failures). The offset given back for each record will always be set to –1.

1: The leader will write the record to its local log but will respond without waiting until receiving full acknowledgement from all followers. If the leader fails immediately after acknowledging the record but before the followers have replicated it, the record will be lost.

all: The leader will wait for the full set of replicas to acknowledge the record. This is the strongest available guarantee that the record will not be lost as long as there is at least one replica.

retries

0

0

Setting this parameter to a value greater than zero will cause the client to resend any record that failed to be sent due to a potentially transient error.

Note that this retry is no different than if the client resent the record upon receiving the error. Allowing retries will potentially change the ordering of records because if two batches are sent to the same partition, and the first fails and is retried but the second succeeds, then the records in the second batch may appear first.

request.timeout.ms

30000

120000

Indicates the maximum amount of time the client will wait for the response of a request. If the response is not received before the timeout elapses, the client will throw a Timeout exception.

block.on.buffer.full

TRUE

The default value

When buffer memory is exhausted, the producer must stop receiving new message records or throw an exception. By default, this parameter is set to TRUE. However, in some cases, non-blocking usage is desired and it is better to throw an exception immediately.

Setting this parameter to FALSE will cause the producer to instead throw an BufferExhaustedException when buffer memory is exhausted.

batch.size

16384

262144

The producer will attempt to batch records together into fewer requests whenever multiple records are being sent to the same partition. This helps improve performance of both the client and the server. This parameter controls the default batch size in bytes.

No attempt will be made to batch records larger than this size.

Requests sent to brokers will contain multiple batches, one for each partition with data available to be sent.

A smaller batch size will make batching less common and may reduce throughput (a batch size of zero will disable batching entirely). A larger batch size may use more memory as a buffer of the specified batch size will always be allocated in anticipation of additional records.

buffer.memory

33554432

536870912

The total bytes of memory the producer can use to buffer records waiting to be sent to the server. If records are sent faster than they can be delivered to the broker, the producer will stop sending records or throw a block.on.buffer.full exception.

This setting should correspond roughly to the total memory the producer will use, but is not a hard bound since not all memory the producer uses is used for buffering. Some additional memory will be used for compression (if compression is enabled) as well as for maintaining in-flight requests.

Table 2 Consumer parameters

Parameter

Default Value

Recommended Value

Description

auto.commit.enable

TRUE

FALSE

If this parameter is set to TRUE, the offset of messages already fetched by the consumer will be periodically committed to ZooKeeper. This committed offset will be used when the process fails as the position from which the new consumer will begin.

Constraints: If this parameter is set to FALSE, to avoid message loss, an offset must be committed to ZooKeeper after the messages are successfully consumed.

auto.offset.reset

latest

earliest

Indicates what to do when there is no initial offset in ZooKeeper or if the current offset has been deleted.

Options:

earliest: The offset is automatically reset to the smallest offset.

latest: The offset is automatically reset to the largest offset.

none: The system throws an exception to the consumer if no offset is available.

anything else: The system throws an exception to the consumer.

connections.max.idle.ms

600000

30000

Indicates the timeout interval for an idle connection. The server closes the idle connection after this period of time ends.

Setting this parameter to 30000 can reduce the server response failures when the network condition is poor.