THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Status
Current state: Under DiscussionAccepted
Discussion thread: here
JIRA:
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PR: https://github.com/apache/kafka/pull/6686
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
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Public Interfaces
Network protocol
Request
Added a top level property called ElectionType with supported values of 0 and 1.
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{
"apiKey": 43,
"type": "request",
"name": "ElectLeadersRequest",
"validVersions": "0-1",
"fields": [
{ "name": "ElectionType", "type": "int8", "versions": "1+",
"about": "Type of elections to conduct for the partition. A value of '0' elects the preferred replica. A value of '1' elects the first live replica if there are no in-sync replica." },
{ "name": "TopicPartitions", "type": "[]TopicPartitions", "versions": "0+", "nullableVersions": "0+",
"about": "The topic partitions to elect leaders.",
"fields": [
{ "name": "Topic", "type": "string", "versions": "0+",
"about": "The name of a topic." },
{ "name": "PartitionId", "type": "[]int32", "versions": "0+",
"about": "The partitions of this topic whose leader should be elected." }
]
},
{ "name": "TimeoutMs", "type": "int32", "versions": "0+", "default": "60000",
"about": "The time in ms to wait for the election to complete." }
]
} |
AdminClient Abstract Class
Response
Added a top level property called ErrorCode for returning errors that apply to all the topic partitions. The current implementation is using this to return cluster authorization errors.
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{
"apiKey": 43,
"type": "response",
"name": "ElectLeadersResponse",
"validVersions": "0-1",
"fields": [
{ "name": "ThrottleTimeMs", "type": "int32", "versions": "0+",
"about": "The duration in milliseconds for which the request was throttled due to a quota violation, or zero if the request did not violate any quota." },
{ "name": "ErrorCode", "type": "int16", "versions": "1+", "ignorable": false,
"about": "The top level response error code." },
{ "name": "ReplicaElectionResults", "type": "[]ReplicaElectionResult", "versions": "0+",
"about": "The election results, or an empty array if the requester did not have permission and the request asks for all partitions.", "fields": [
{ "name": "Topic", "type": "string", "versions": "0+", "entityType": "topicName",
"about": "The topic name" },
{ "name": "PartitionResult", "type": "[]PartitionResult", "versions": "0+",
"about": "The results for each partition", "fields": [
{ "name": "PartitionId", "type": "int32", "versions": "0+",
"about": "The partition id" },
{ "name": "ErrorCode", "type": "int16", "versions": "0+",
"about": "The result error, or zero if there was no error."},
{ "name": "ErrorMessage", "type": "string", "versions": "0+", "nullableVersions": "0+",
"about": "The result message, or null if there was no error."}
]}
]}
]
} |
AdminClient Abstract Class
A new method will be added to the AdminClient abstract class to support this new version of the RPC.
When the partition parameter is null the controller will attempt the election type on all of partitions that are legible for election. This means that the RPC will only return success or failure on partition that eligible for election as oppose to all of the partitions in the cluster as the previous implemented behavedA new method will be added to the AdminClient abstract class to support this new version of the RPC.
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package org.apache.kafka.clients.admin;
public abstract class AdminClient ... {
...
/**
* ...
* @deprecated Since TBD2.4.0. Use {@link #electLeaders}.
*/
@Deprecated
public abstract ElectPreferredLeadersResult electPreferredLeaders(Collection<TopicPartition> partitions,
ElectPreferredLeadersOptions options);
/**
* Attempt to elect a new leader for each of the topic partition in {@code partitions} using the {@code electionType} election.
* The type of elections supported are document in the {@link ElectionType} type* ...
*
* @param electionType The type of election.
*
@param partitions * If {@code partitions} is null, then attempt to perform theThe electionpartitions for allwhich ofto theconduct topic partitionselections.
*
@param options * @param electionType The type of election options to use when electing the leaders.
* @param@return partitions The partitions for which to conduct elections.
The ElectLeadersResult.
* @param options */
public abstract ElectLeadersResult electLeaders(
The options to use when electing the leaders.ElectionType electionType,
* @return Set<TopicPartition> partitions,
ElectLeadersOptions options);
} |
ElectLeaderResult Class
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final public ElectLeadersResult The ElectLeadersResult.{ */... public abstract ElectLeadersResult electLeaders( KafkaFuture<Map<TopicPartition, Optional<Throwable>>> partitions() { ElectionType electionType,... } public KafkFuture<Void> Collection<TopicPartition> partitions,all() { ... ElectLeadersOptions options);} } |
ElectionType Enumeration
...
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$ bin/kafka-leader-election.sh --help
This tool attempts to elect a new leader for a set of topic partitions. The type of elections supported are preferred replicas and unclean replica.
Option Description
------ -----------
--admin.config <String: config file> Admin client config properties file to pass to the admin
client when --bootstrap-server is given.
--all-topic-partitions Perform election on all of the topic partitions. Not allowed if
--topic, --partition or --path-to-json-file is specified.
--bootstrap-server <String: host:port> A host name and port for the broker to
connect to, in the form host:port.
Multiple comma-separated URLs can be
given. REQUIRED unless --zookeeper
is given.
--election-type <String: election> Type of election to attempt. Possible values are "preferred"
for preferred election or "unclean" for unclean election.
REQUIRED.
--topic <String: topic> Name of topic for which to perform an election.
REQUIRED if --partition is specified. Not allowed
if --path-to-json-file or --all-topic-partitions is specified.
--partition <Integer: partition id> Partition id for which to perform an election.
REQUIRED if --topic is specified. Not allowed if
--path-to-json-file or --all-topic-partitions is specified.
--help Print usage information.
--path-to-json-file <String: list of The JSON file with the list of
partitions for which replica partitions for which leader election
leader election needs to be should be done. Supported elections
triggered> are 0 for preferred and 1 for unclean.
If an election is not specified,
preferred is the default. This is an
example format.
{"partitions":
[{"topic": "foo", "partition": 1},
{"topic": "foobar", "partition": 2}]
}
Not allowed if --all-topic-partitions, --topic-partitions, --topic or --partition
or --partition
flags flags are specified.are specified. |
Metrics
The following metrics were added:
- kafka.server:type=DelayedOperationPurgatory,name=NumDelayedOperations,delayedOperation=ElectLeader
- kafka.server:type=DelayedOperationPurgatory,name=PurgatorySize,delayedOperation=ElectLeader
While the following metrics were removed:
- kafka.server:type=DelayedOperationPurgatory,name=NumDelayedOperations,delayedOperation=ElectPreferredLeader
- kafka.server:type=DelayedOperationPurgatory,name=PurgatorySize,delayedOperation=ElectPreferredLeader
Proposed Changes
In addition to the protocol and client changes enumerated above, the Controller will be extended to allow unclean leader election requests to come from the admin client. Currently the controller only supports preferred leader election from the admin client. Unclean leader election can only be enabled through either a topic configuration change or a broker configuration change.
...
- The kafka-preferred-replica-elections.{sh,bat} scripts will be deprecated.
- The electPreferredLeaders method in AdminClient will be deprecated.
- The DelayedOperationPurgatory metrics ElectPreferredLeader were replaced with ElectLeader
Rejected Alternatives
Not applicable.