What is OffsetCommit?
Every consumer sends this after processing records to checkpoint its position into __consumer_offsets. Commit failures during rebalances (REBALANCE_IN_PROGRESS, ILLEGAL_GENERATION) are the root cause of duplicate processing in at-least-once consumers.
Wire Diagram
Response Header · flexible
message_size
int32 · 4B
correlation_id
int32 · 4B
tagged
var
OffsetCommitResponse v8
ThrottleTimeMs
int32 · 4B
tagged
var
Name
string (compact)
tagged
var
PartitionIndex
int32 · 4B
ErrorCode
int16 · 2B
tagged
var
Schema & Example
Schema { "ThrottleTimeMs": int32, "Topics": [{ "Name": string, "Partitions": [{ "PartitionIndex": int32, "ErrorCode": int16 }] }] }
Example { "ThrottleTimeMs": 0, "Topics": [{ "Name": "orders", "Partitions": [{ "PartitionIndex": 3, "ErrorCode": 0 }] }] }