RocketMQ proxyΒΆ

Apache RocketMQ is a distributed messaging system, which is composed of four types of roles: producer, consumer, name server and broker server. The former two are embedded into user application in form of SDK; whilst the latter are standalone servers.

A message in RocketMQ carries a topic as its destination and optionally one or more tags as application specific labels.

Producers are used to send messages to brokers according to their topics. Similar to many distributed systems, producers need to know how to connect to these serving brokers. To achieve this goal, RocketMQ provides name server clusters for producers to lookup. Namely, when producers attempts to send messages with a new topic, it first tries to lookup the addresses(called route info) of brokers that serve the topic from name servers. Once producers get the route info of the topic, they actively cache them in memory and renew them periodically thereafter. This mechanism, though simple, effectively keeps service availability high without demanding availability of name server service.

Brokers provides messaging service to end users. In addition to various messaging services, they also periodically report health status and route info of topics currently served to name servers.

Major role of the name server is to serve querying of route info for a topic. Additionally, it also purges route info entries once the belonging brokers fail to report their health info for a configured period of time. This ensures clients almost always connect to brokers that are online and ready to serve.

Consumers are used by application to pull message from brokers. They perform similar heartbeats to maintain alive status. RocketMQ brokers support two message-fetch approaches: long-pulling and pop.

Using the first approach, consumers have to implement load-balancing algorithm. The pop approach, in the perspective of consumers, is stateless.

Envoy RocketMQ filter proxies requests and responses between producers/consumer and brokers. Various statistical items are collected to enhance observability.

At present, pop-based message fetching is implemented. Long-pulling will be implemented in the next pull request.

StatisticsΒΆ

Every configured rocketmq proxy filter has statistics rooted at rocketmq.<stat_prefix>. with the following statistics:

Name

Type

Description

request

Counter

Total requests

request_decoding_error

Counter

Total decoding error requests

request_decoding_success

Counter

Total decoding success requests

response

Counter

Total responses

response_decoding_error

Counter

Total decoding error responses

response_decoding_success

Counter

Total decoding success responses

response_error

Counter

Total error responses

response_success

Counter

Total success responses

heartbeat

Counter

Total heartbeat requests

unregister

Counter

Total unregister requests

get_topic_route

Counter

Total getting topic route requests

send_message_v1

Counter

Total sending message v1 requests

send_message_v2

Counter

Total sending message v2 requests

pop_message

Counter

Total poping message requests

ack_message

Counter

Total acking message requests

get_consumer_list

Counter

Total getting consumer list requests

maintenance_failure

Counter

Total maintenance failure

request_active

Gauge

Total active requests

send_message_v1_active

Gauge

Total active sending message v1 requests

send_message_v2_active

Gauge

Total active sending message v2 requests

pop_message_active

Gauge

Total active poping message active requests

get_topic_route_active

Gauge

Total active geting topic route requests

send_message_pending

Gauge

Total pending sending message requests

pop_message_pending

Gauge

Total pending poping message requests

get_topic_route_pending

Gauge

Total pending geting topic route requests

total_pending

Gauge

Total pending requests

request_time_ms

Histogram

Request time in milliseconds