Andrei Iatsuk created KAFKA-12481:
-------------------------------------
Summary: Add socket.nagle.disable config to reduce number of
packets
Key: KAFKA-12481
URL: https://issues.apache.org/jira/browse/KAFKA-12481
Project: Kafka
Issue Type: Improvement
Components: core
Affects Versions: 2.6.1, 2.7.0, 2.5.1, 2.4.1, 2.3.1, 2.2.2, 2.1.1, 2.0.1,
1.1.1, 1.0.2, 0.11.0.3, 0.10.2.2, 0.8.2.2
Reporter: Andrei Iatsuk
Attachments: Screenshot 2021-03-13 at 00.29.10.png, Screenshot
2021-03-13 at 00.44.43.png, Screenshot 2021-03-14 at 01.46.00.png, Screenshot
2021-03-14 at 01.52.01.png, Screenshot 2021-03-16 at 21.05.03.png, Screenshot
2021-03-16 at 21.12.17.png
*What to do?*
Add _socket.nagle.disable_ parameter to Apache Kafka config like in
[librdkafka|https://github.com/edenhill/librdkafka/blob/master/CONFIGURATION.md].
*What reason of this improvement?*
A large number of topic-partitions on one broker causes burst of host's
packets/sec metric. The traffic shaper in the cloud ceases to cope with such a
load and causes service degradation.
*How to reproduce?*
# Create Kafka Cluster with 4 brokers. Amount of packet/sec is ~120.
# Add 100 topics with 100 partitions each and replication factor = 3. It is
30k topic-partitions in total. Amount of packet/sec is ~15k.
{code:java}
import os
for i in range(100):
print(f"create topic 'flower{i}'... ", end="")
cmd = "kafka-topics.sh --create --bootstrap-server {} --topic {} --partitions
{} --replication-factor {}".format("databus.andrei-iatsuk.ec.odkl.ru:9092",
f"flower{i}", 100, 3)
code = os.system(cmd)
print("ok" if code == 0 else "error")
{code}
!Screenshot 2021-03-16 at 21.05.03.png!
# Generate server load by launching next script in 4 terminals. Amount of
packet/sec is ~130k.
{code:java}
import time
from pykafka import KafkaClient
client = KafkaClient(hosts="databus.andrei-iatsuk.ec.odkl.ru:9092")
while True:
for i in range(100):
print(f"sent message to 'flower{i}'")
with client.topics[f"flower{i}"].get_sync_producer() as producer:
for j in range(1000):
producer.produce(str.encode(f'test message {j} in topic flower{i}' *
10))
{code}
!Screenshot 2021-03-13 at 00.44.43.png!
!Screenshot 2021-03-13 at 00.29.10.png!
# Make dump of tcp connections via tcpdump due ~2 sec:
{code:java}
$ tcpdump -i eth1 -w dump.pcap
tcpdump: listening on eth1, link-type EN10MB (Ethernet), capture size 262144
bytes
^C8873886 packets captured
9139050 packets received by filter
265028 packets dropped by kernel
{code}
# Load dump to Wireshark and see statistics: ~99.999% of packets is inter
broker messages, size of packets 40-160 bytes. On screen hosts with IPs
10.16.23.[157-160] is brokers:
!Screenshot 2021-03-14 at 01.46.00.png!
!Screenshot 2021-03-14 at 01.52.01.png!
*How to fix?*
# Add boolean _socket.nagle.disable_ parameter to Apache Kafka config and
provide value to kafka.network.Acceptor.accept(key) method in :
[https://github.com/apache/kafka/blob/2.4/core/src/main/scala/kafka/network/SocketServer.scala#L646]
# For disabled TCP_NODELAY value:
## ~400 packets/s for idle broker (instead ~12k packets/s)
## ~3k packets/s for loaded broker (instead ~150k packets/s)
!Screenshot 2021-03-16 at 21.12.17.png!
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