Unlocking RocketMQ: What Every SendResult Field Means

RocketMQ series article: "10‑minute RocketMQ: Java client practical guide (including detailed API)". The previous article covered usage of the RocketMQ Java client but left the question of which parameters are included in the return object after a successful send.

The result object of a successful synchronous send is SendResult. Below is an analysis of each field:

1 SendResult [
  sendStatus=SEND_OK,
  msgId=FDE6CE25AA470000185BBACBDC06F282647B18B4AAC2368769320000,
  offsetMsgId=7925BA3A00002A9F0000000000000000,
  messageQueue=MessageQueue [topic=pay-mini-pay-test, brokerName=broker-a, queueId=2],
  queueOffset=0
]

Field Details

Field

Meaning

Description

sendStatus

Sending status SEND_OK indicates the message was successfully stored in the broker.

msgId

Message ID

The globally unique ID generated for the message, used for tracing and troubleshooting.

offsetMsgId

Message physical offset

Represents the physical storage location of the message on the broker.

messageQueue

Message queue information

Indicates which topic, broker, and queue the message was sent to.

queueOffset

Queue offset

Shows the position (index) of the message within the queue.

Detailed Breakdown

1. sendStatus

SEND_OK

means the message has been successfully stored in the broker.

Other possible statuses include: FLUSH_DISK_TIMEOUT: Disk flush timeout (may be due to synchronous flush configuration). FLUSH_SLAVE_TIMEOUT: Sync to slave timeout. SLAVE_NOT_AVAILABLE: Slave not available, cannot complete master‑slave sync.

2. msgId

The msgId is a globally unique ID generated by RocketMQ, for example:

FDE6CE25AA470000185BBACBDC06F282647B18B4AAC2368769320000

It consists of the IP address (8 bytes), port (4 bytes), process ID (4 bytes), timestamp (8 bytes), and a sequence number (8 bytes).

3. offsetMsgId

Represents the physical offset address of the message in the broker.

Format includes Broker ID, Queue ID, and physical position.

4. messageQueue

Shows the queue information where the message is stored:

MessageQueue [topic=pay-mini-pay-test, brokerName=broker-a, queueId=2]

Attribute

Explanation

Value

topic

Topic name pay-mini-pay-test brokerName

Broker name broker-a queueId

Queue ID 2 (the second queue on broker‑a)

5. queueOffset

Indicates the offset of the message within the queue (starting from 0).

Used by consumers to locate the message position.

Understanding SendResult is essential to truly grasp RocketMQ's message‑sending mechanism.