class Kafkat::Command::Reassign
Public Instance Methods
add_partition_to_all_lowest( tp, nb_partitions_to_add )
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Add a topic partition to lowest unbalanced nodes you can specify the number of times the partition must be added to fit its minimal replica count
# File lib/kafkat/command/reassign.rb, line 138 def add_partition_to_all_lowest( tp, nb_partitions_to_add ) nodes_sizes_replicas = @nodes_lists_replicas.hmap { |k,v| { k => v.size } } nodes_lowest = nodes_sizes_replicas.sort_by{|k,v| v}.map { |a| a[0] } nodes_lowest.each do |node| break if nb_partitions_to_add <= 0 unless @nodes_lists_replicas[node].has_key?(tp) add_partition_to_node( tp, node ) nb_partitions_to_add -= 1 end end end
add_partition_to_node( tp, node )
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Add a topic partition to a specific node
# File lib/kafkat/command/reassign.rb, line 128 def add_partition_to_node( tp, node ) @nodes_lists_replicas[node][tp] = '' @partitions_lists[tp]['replicas'] ||= {} @partitions_lists[tp]['replicas'][node] = '' end
migrate_excess_replicas_from_node( node, nb_partitions_to_remove )
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Migrate excess replicas from node to lowest unbalanced nodes It chooses absent replicas from lowest unbalanced nodes, to make sure we fill the lowest BUG: There is very probably an issue here in case the lowest node has less than `nb_partitions_to_remove` absent partitions from source node
# File lib/kafkat/command/reassign.rb, line 202 def migrate_excess_replicas_from_node( node, nb_partitions_to_remove ) # This method is not efficient, but that is not something you run often nb_partitions_to_remove.times do |i| # Find out the lowest balanced nodes nodes_sizes_replicas = @nodes_lists_replicas.hmap { |k,v| { k => v.size } } node_lowest = nodes_sizes_replicas.sort_by{|k,v| v}[0][0] # Find out which partitions the lowest balanced node does not have and which can be migrated from this node partition_to_migrate = (@nodes_lists_replicas[node].keys - @nodes_lists_replicas[node_lowest].keys)[0] remove_partition_from_node( partition_to_migrate, node ) add_partition_to_node( partition_to_migrate, node_lowest ) end # # Find out the lowest balanced nodes # nodes_sizes_replicas = @nodes_lists_replicas.hmap { |k,v| { k => v.size } } # nodes_lowest = nodes_sizes_replicas.sort_by{|k,v| v}.map { |a| a[0] } # nodes_lowest.each do |node_lowest| # break if nb_partitions_to_remove <= 0 # # Find out which partitions the lowest balanced node does not have and which can be migrated from this node # partitions_to_migrate = @nodes_lists_replicas[node].keys - @nodes_lists_replicas[node_lowest].keys # partitions_to_migrate.each do |tp| # break if nb_partitions_to_remove <= 0 # remove_partition_from_node( tp, node ) # add_partition_to_node( tp, node_lowest ) # nb_partitions_to_remove -= 1 # end # end end
remove_excess_replicas_from_node( node, nb_partitions_to_remove )
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Remove excess replicas from node If nb_partitions_to_remove is nil, then remove all excess replicas First remove partitions which are not in ISR and already replicated enough times on other nodes of the cluster Then regardless of ISR
# File lib/kafkat/command/reassign.rb, line 167 def remove_excess_replicas_from_node( node, nb_partitions_to_remove ) # First remove partitions which are not in ISR and already replicated enough times on other nodes of the cluster replicas_not_isr = @nodes_lists_replicas[node].keys - @nodes_lists_isr[node].keys replicas_not_isr_over_replicated = replicas_not_isr.keep_if { |tp| @partitions_lists[tp]['replicas'].keys.size > @replica_count } replicas_not_isr_over_replicated.each do |tp| break if (!nb_partitions_to_remove.nil? && nb_partitions_to_remove <= 0) remove_partition_from_node( tp, node ) nb_partitions_to_remove -= 1 unless nb_partitions_to_remove.nil? end # Then remove partitions which regardless of ISR and already replicated enough times on other nodes of the cluster replicas_over_replicated = @nodes_lists_replicas[node].keys.keep_if { |tp| @partitions_lists[tp]['replicas'].keys.size > @replica_count } replicas_over_replicated.each do |tp| break if (!nb_partitions_to_remove.nil? && nb_partitions_to_remove <= 0) remove_partition_from_node( tp, node ) nb_partitions_to_remove -= 1 unless nb_partitions_to_remove.nil? end end
remove_partition_from_node( tp, node )
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# File lib/kafkat/command/reassign.rb, line 154 def remove_partition_from_node( tp, node ) @nodes_lists_replicas[node].delete tp @nodes_lists_isr[node].delete tp @partitions_lists[tp]['replicas'].delete(node) @partitions_lists[tp]['isr'].delete(node) end
run()
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# File lib/kafkat/command/reassign.rb, line 32 def run topic_names = ARGV.shift unless ARGV[0] && ARGV[0].start_with?('--') all_brokers = zookeeper.get_brokers topics = nil if topic_names topics_list = topic_names.split(',') topics = zookeeper.get_topics(topics_list) end topics ||= zookeeper.get_topics opts = Trollop.options do opt :brokers, "replica set (broker IDs)", type: :string opt :replicas, "number of replicas (count)", type: :integer end broker_ids = opts[:brokers] && opts[:brokers].split(',').map(&:to_i) replica_count = opts[:replicas] broker_ids ||= zookeeper.get_brokers.values.map(&:id) all_brokers_id = all_brokers.values.map(&:id) broker_ids.each do |id| if !all_brokers_id.include?(id) print "ERROR: Broker #{id} is not currently active.\n" exit 1 end end # *** This logic is duplicated from Kakfa 0.8.1.1 *** assignments = [] broker_count = broker_ids.size # Helper structures @replica_count = replica_count @nodes_lists_replicas = {} @nodes_lists_isr = {} @partitions_lists={} @partitions_lists_old={} topics.each do |_, t| # This is how Kafka's AdminUtils determines these values. partition_count = t.partitions.size topic_replica_count = replica_count || t.partitions[0].replicas.size if topic_replica_count > broker_count print "ERROR: Replication factor (#{topic_replica_count}) is larger than brokers (#{broker_count}).\n" exit 1 end # start_index = Random.rand(broker_count) # replica_shift = Random.rand(broker_count) # t.partitions.each do |p| # replica_shift += 1 if p.id > 0 && p.id % broker_count == 0 # first_replica_index = (p.id + start_index) % broker_count # replicas = [broker_ids[first_replica_index]] # (0...topic_replica_count-1).each do |i| # shift = 1 + (replica_shift + i) % (broker_count - 1) # index = (first_replica_index + shift) % broker_count # replicas << broker_ids[index] # end # replicas.reverse! # assignments << Assignment.new(t.name, p.id, replicas) # end t.partitions.each do |p| @partitions_lists[p.topic_name + ' ' + p.id.to_s] ||= {'name'=>p.topic_name, 'id'=>p.id, 'replicas'=>{},'isr'=>{}} @partitions_lists_old[p.topic_name + ' ' + p.id.to_s] ||= {'name'=>p.topic_name, 'id'=>p.id, 'replicas'=>{},'isr'=>{}} p.replicas.each do |node| @partitions_lists[p.topic_name + ' ' + p.id.to_s]['replicas'][node] = '' @partitions_lists_old[p.topic_name + ' ' + p.id.to_s]['replicas'][node] = '' @nodes_lists_replicas[node] ||= {} @nodes_lists_replicas[node][p.topic_name + ' ' + p.id.to_s] = '' end p.isr.each do |node| @partitions_lists[p.topic_name + ' ' + p.id.to_s]['isr'][node] = '' @partitions_lists_old[p.topic_name + ' ' + p.id.to_s]['isr'][node] = '' # nodes_sizes_isr[node] ||= 0 # nodes_sizes_isr[node] += 1 @nodes_lists_isr[node] ||= {} @nodes_lists_isr[node][p.topic_name + ' ' + p.id.to_s] = '' end end end # Add a topic partition to a specific node def add_partition_to_node( tp, node ) @nodes_lists_replicas[node][tp] = '' @partitions_lists[tp]['replicas'] ||= {} @partitions_lists[tp]['replicas'][node] = '' end # Add a topic partition to lowest unbalanced nodes # you can specify the number of times the partition must be added to fit its minimal replica count def add_partition_to_all_lowest( tp, nb_partitions_to_add ) nodes_sizes_replicas = @nodes_lists_replicas.hmap { |k,v| { k => v.size } } nodes_lowest = nodes_sizes_replicas.sort_by{|k,v| v}.map { |a| a[0] } nodes_lowest.each do |node| break if nb_partitions_to_add <= 0 unless @nodes_lists_replicas[node].has_key?(tp) add_partition_to_node( tp, node ) nb_partitions_to_add -= 1 end end end def remove_partition_from_node( tp, node ) @nodes_lists_replicas[node].delete tp @nodes_lists_isr[node].delete tp @partitions_lists[tp]['replicas'].delete(node) @partitions_lists[tp]['isr'].delete(node) end # Remove excess replicas from node # If nb_partitions_to_remove is nil, then remove all excess replicas # First remove partitions which are not in ISR and already replicated enough times on other nodes of the cluster # Then regardless of ISR def remove_excess_replicas_from_node( node, nb_partitions_to_remove ) # First remove partitions which are not in ISR and already replicated enough times on other nodes of the cluster replicas_not_isr = @nodes_lists_replicas[node].keys - @nodes_lists_isr[node].keys replicas_not_isr_over_replicated = replicas_not_isr.keep_if { |tp| @partitions_lists[tp]['replicas'].keys.size > @replica_count } replicas_not_isr_over_replicated.each do |tp| break if (!nb_partitions_to_remove.nil? && nb_partitions_to_remove <= 0) remove_partition_from_node( tp, node ) nb_partitions_to_remove -= 1 unless nb_partitions_to_remove.nil? end # Then remove partitions which regardless of ISR and already replicated enough times on other nodes of the cluster replicas_over_replicated = @nodes_lists_replicas[node].keys.keep_if { |tp| @partitions_lists[tp]['replicas'].keys.size > @replica_count } replicas_over_replicated.each do |tp| break if (!nb_partitions_to_remove.nil? && nb_partitions_to_remove <= 0) remove_partition_from_node( tp, node ) nb_partitions_to_remove -= 1 unless nb_partitions_to_remove.nil? end end # Migrate excess replicas from node to lowest unbalanced nodes # It chooses absent replicas from lowest unbalanced nodes, to make sure we fill the lowest # BUG: There is very probably an issue here in case the lowest node has less than `nb_partitions_to_remove` absent partitions from source node def migrate_excess_replicas_from_node( node, nb_partitions_to_remove ) # This method is not efficient, but that is not something you run often nb_partitions_to_remove.times do |i| # Find out the lowest balanced nodes nodes_sizes_replicas = @nodes_lists_replicas.hmap { |k,v| { k => v.size } } node_lowest = nodes_sizes_replicas.sort_by{|k,v| v}[0][0] # Find out which partitions the lowest balanced node does not have and which can be migrated from this node partition_to_migrate = (@nodes_lists_replicas[node].keys - @nodes_lists_replicas[node_lowest].keys)[0] remove_partition_from_node( partition_to_migrate, node ) add_partition_to_node( partition_to_migrate, node_lowest ) end # # Find out the lowest balanced nodes # nodes_sizes_replicas = @nodes_lists_replicas.hmap { |k,v| { k => v.size } } # nodes_lowest = nodes_sizes_replicas.sort_by{|k,v| v}.map { |a| a[0] } # nodes_lowest.each do |node_lowest| # break if nb_partitions_to_remove <= 0 # # Find out which partitions the lowest balanced node does not have and which can be migrated from this node # partitions_to_migrate = @nodes_lists_replicas[node].keys - @nodes_lists_replicas[node_lowest].keys # partitions_to_migrate.each do |tp| # break if nb_partitions_to_remove <= 0 # remove_partition_from_node( tp, node ) # add_partition_to_node( tp, node_lowest ) # nb_partitions_to_remove -= 1 # end # end end ### # At this point, the helper structures represent the current repartition of partitions # We will modify the helper structures to balance the partitions accross brokers whith the minimum number of partitions moves ### # Add under replicated partitions to lowest unbalanced nodes partitions_under_replicated = @partitions_lists.keys.keep_if { |tp| @partitions_lists[tp]['replicas'].size < @replica_count } partitions_under_replicated.each do |tp| how_many = @replica_count - @partitions_lists[tp]['replicas'].size add_x_to_all_lowest( tp, how_many ) end # Begin leaning and draining nodes with the most partitions towards the lowest unbalanced nodes 2.times do |i| # List all nodes from biggest to lowest balanced nodes_sizes_replicas = @nodes_lists_replicas.hmap { |k,v| { k => v.size } } nodes_biggest = nodes_sizes_replicas.sort_by{|k,v| v}.reverse.map { |a| a[0] } # helper count of partition replicas to balance nodes_left_to_balance = nodes_biggest.size nb_partitions_left_to_balance = @replica_count * @partitions_lists.keys.size # Remove excess replicas on all nodes from biggest to lowest unbalanced nodes, until balance is achieved nodes_biggest.each do |node| # Figure out the numbers of partitions each node should have to be balanced # I am wary about float operations, for example to do a 5.00000001.ceil() # nb_partitions_should_have = ( nb_partitions_left_to_balance / nodes_left_to_balance.to_f ).ceil nb_partitions_should_have = nb_partitions_left_to_balance / nodes_left_to_balance nb_partitions_should_have += 1 if (nb_partitions_left_to_balance % nodes_left_to_balance) > 0 # nb_partitions_to_remove = @nodes_lists_replicas[node].keys.size - nb_partitions_should_have.ceil nb_partitions_to_remove = @nodes_lists_replicas[node].keys.size - nb_partitions_should_have remove_excess_replicas_from_node( node, nb_partitions_to_remove) if nb_partitions_to_remove > 0 # nb_partitions_to_remove = @nodes_lists_replicas[node].keys.size - nb_partitions_should_have.ceil nb_partitions_to_remove = @nodes_lists_replicas[node].keys.size - nb_partitions_should_have migrate_excess_replicas_from_node( node, nb_partitions_to_remove) if nb_partitions_to_remove > 0 nodes_left_to_balance -= 1 nb_partitions_left_to_balance = nb_partitions_left_to_balance - nb_partitions_should_have end end # Remove excess replicas on all nodes from lowest unbalanced nodes to biggest nodes. This is to enforce replica count, and if the whole algorithm is fine, it should do nothing nodes_sizes_replicas = @nodes_lists_replicas.hmap { |k,v| { k => v.size } } nodes_biggest = nodes_sizes_replicas.sort_by{|k,v| v}.reverse.map { |a| a[0] } nodes_biggest.each do |node| remove_excess_replicas_from_node( node, nil ) end require 'pp' puts "\nCurrent partition assignment:" pp @partitions_lists_old.hmap { |k,v| { k => { 'replicas'=>v['replicas'], 'isr'=>v['isr']} } } puts "\nOptimized partition assignment with minimal partition migrations:" pp @partitions_lists.hmap { |k,v| { k => { 'replicas'=>v['replicas'], 'isr'=>v['isr']} } } puts '' @partitions_lists.each_key do |tp| assignments << Assignment.new( @partitions_lists[tp]['name'], @partitions_lists[tp]['id'], @partitions_lists[tp]['replicas'].keys, ) end # **************** prompt_and_execute_assignments(assignments) end