THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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"apiKey": 55,
"type": "response",
"name": "DescribeQuorumResponse",
"validVersions": "0-1",
"flexibleVersions": "0+",
"fields": [
{ "name": "ErrorCode", "type": "int16", "versions": "0+",
"about": "The top level error code."},
{ "name": "Topics", "type": "[]TopicData",
"versions": "0+", "fields": [
{ "name": "TopicName", "type": "string", "versions": "0+", "entityType": "topicName",
"about": "The topic name." },
{ "name": "Partitions", "type": "[]PartitionData",
"versions": "0+", "fields": [
{ "name": "PartitionIndex", "type": "int32", "versions": "0+",
"about": "The partition index." },
{ "name": "ErrorCode", "type": "int16", "versions": "0+"},
{ "name": "LeaderId", "type": "int32", "versions": "0+", "entityType": "brokerId",
"about": "The ID of the current leader or -1 if the leader is unknown."},
{ "name": "LeaderEpoch", "type": "int32", "versions": "0+",
"about": "The latest known leader epoch"},
{ "name": "HighWatermark", "type": "int64", "versions": "0+"},
{ "name": "CurrentVoters", "type": "[]ReplicaState", "versions": "0+" },
{ "name": "Observers", "type": "[]ReplicaState", "versions": "0+" }
]}
]}],
"commonStructs": [
{ "name": "ReplicaState", "versions": "0+", "fields": [
{ "name": "ReplicaId", "type": "int32", "versions": "0+", "entityType": "brokerId" },
{ "name": "LogEndOffset", "type": "int64", "versions": "0+",
"about": "The last known log end offset of the follower or -1 if it is unknown"},
{ "name": "LastFetchTimeLastFetchTimestamp", "type": "int64", "versions": "1+",
"about": "The last known leader wall clock time time when a follower fetched from the leader. This is reported as -1 both for the current leader or if it is unknown for a voter"},
{ "name": "LastCaughtUpTimeLastCaughtUpTimestamp", "type": "int64", "versions": "1+",
"about": "The leader wall clock append time of the offset for which the follower made the most recent fetch request. This is reported as the current time for the leader and -1 if unknown for a voter"}
]}
] |
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These fields are intended to approximate the "time-lag" between the leader and the followers in the quorum.
LastFetchTimestampLast Fetch Time
This metric will be reported for each voter. This is a good approximation of the “liveness” of the voters and can be used to detect a network partition in the quorum.
This information is already known to the leader for all voters and only needs to be added to the responseLastCaughtUpTimestampLast Caught Up Time
This metric will be reported for each voter. This is akin to the metric used to track lag for replicas in ISR and it measures the approximate lag between the leader and the replica based on the offsets requested in the fetch requests and when they were made. The metric gives a measure of when was the last time a replica caught up to the leader. .
To compute this metric, the Replica state maintains a few bits of information about fetch requests as they are received. Some of this information is not tracked by the Raft layer but it can be easily added in. The cost to track this information is minimal and it only requires some additional bookkeeping during pre-existing processing for a fetch.
NOTE: Given the leader is always caught up to itself, the Last Caught Up Time for the leader will be the leader's wall clock time when it responded to theDescribeQuorumrequest.
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