Class: SwitchmanInstJobs::JobsMigrator
- Inherits:
-
Object
- Object
- SwitchmanInstJobs::JobsMigrator
- Defined in:
- lib/switchman_inst_jobs/jobs_migrator.rb
Class Method Summary collapse
- .acquire_advisory_lock(type, name) ⇒ Object
- .add_before_move_callback(proc) ⇒ Object
- .add_validation_callback(proc) ⇒ Object
- .blocked_by_migrator?(job_scope) ⇒ Boolean
- .blocked_job_count ⇒ Object
- .blocked_shards ⇒ Object
- .blocked_singletons ⇒ Object
- .blocked_strands ⇒ Object
- .clear_callbacks! ⇒ Object
- .clear_shard_cache(debug_message = nil, default:) ⇒ Object
-
.ensure_unblock_stranded_for(shards) ⇒ Object
if :migrate_strands ran on any shards that fell into scenario 1, then block_stranded never got flipped, so do that now.
- .migrate_everything(batch_size: 1_000) ⇒ Object
- .migrate_shards(shard_map) ⇒ Object
- .migrate_strands(batch_size: 1_000) ⇒ Object
-
.run ⇒ Object
This method expects that all relevant shards already have block_stranded: true but otherwise jobs can be running normally.
- .transaction_on(shards, &block) ⇒ Object
- .unblock_singleton!(singleton) ⇒ Object
- .unblock_strand!(strand, new_parallelism: nil) ⇒ Object
- .unblock_strands(target_shard, batch_size: 10_000) ⇒ Object
Class Method Details
.acquire_advisory_lock(type, name) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 100 def acquire_advisory_lock(type, name) @quoted_function_name ||= ::Delayed::Job.connection.quote_table_name("half_md5_as_bigint") value = (type == :singleton) ? "singleton:#{name}" : name ::Delayed::Job.connection.execute( ::Delayed::Job.sanitize_sql_for_conditions( ["SELECT pg_advisory_xact_lock(#{@quoted_function_name}(?))", value] ) ) end |
.add_before_move_callback(proc) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 9 def add_before_move_callback(proc) @before_move_callbacks ||= [] @before_move_callbacks << proc end |
.add_validation_callback(proc) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 14 def add_validation_callback(proc) @validation_callbacks ||= [] @validation_callbacks << proc end |
.blocked_by_migrator?(job_scope) ⇒ Boolean
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 281 def blocked_by_migrator?(job_scope) job_scope.exists?(source: "JobsMigrator::StrandBlocker") || blocked_shards.exists?(id: job_scope.distinct.pluck(:shard_id)) end |
.blocked_job_count ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 342 def blocked_job_count ::Delayed::Job.from(blocked_strands.select("count(id) AS ssize")).sum("ssize").to_i + ::Delayed::Job.from(blocked_singletons.select("count(id) AS ssize")).sum("ssize").to_i + ::Delayed::Job.where(strand: nil, singleton: nil, next_in_strand: false).count end |
.blocked_shards ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 277 def blocked_shards ::Switchman::Shard.where(block_stranded: true).or(::Switchman::Shard.where(jobs_held: true)) end |
.blocked_singletons ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 315 def blocked_singletons ::Delayed::Job .where(strand: nil) .where.not(singleton: nil) .group(:singleton) .having("NOT BOOL_OR(next_in_strand)") end |
.blocked_strands ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 286 def blocked_strands ::Delayed::Job .where.not(strand: nil) .group(:strand) .having("NOT BOOL_OR(next_in_strand)") end |
.clear_callbacks! ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 19 def clear_callbacks! @before_move_callbacks = [] @validation_callbacks = [] end |
.clear_shard_cache(debug_message = nil, default:) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 89 def clear_shard_cache( = nil, default:) ::Switchman.cache.delete_matched("shard/*") ::Switchman.cache.delete("default_shard") if default Rails.logger.debug { "Waiting for caches to clear #{}" } # Wait a little over the 60 second in-process shard cache clearing # threshold to ensure that all new stranded jobs are now being # enqueued with next_in_strand: false # @skip_cache_wait is for spec usage only sleep(65) unless @skip_cache_wait end |
.ensure_unblock_stranded_for(shards) ⇒ Object
if :migrate_strands ran on any shards that fell into scenario 1, then block_stranded never got flipped, so do that now.
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 76 def ensure_unblock_stranded_for(shards) shards = ::Switchman::Shard.where(id: shards, block_stranded: true).to_a return unless shards.any? ::Switchman::Shard.where(id: shards).update_all(block_stranded: false) clear_shard_cache(default: shards.any?(&:default?)) # shards is an array of shard objects that is now stale cause block_stranded has been updated. shards.map(&:delayed_jobs_shard).uniq.each do |dj_shard| unblock_strands(dj_shard) end end |
.migrate_everything(batch_size: 1_000) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 262 def migrate_everything(batch_size: 1_000) source_shard = ::Switchman::Shard.current(::Delayed::Backend::ActiveRecord::AbstractJob) scope = ::Delayed::Job.shard(source_shard).where(strand: nil) shard_map = build_shard_map(scope, source_shard) shard_map.each do |(target_shard, source_shard_ids)| batch_move_jobs( target_shard: target_shard, source_shard: source_shard, scope: scope.where(shard_id: source_shard_ids).where(locked_by: nil), batch_size: batch_size ) end end |
.migrate_shards(shard_map) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 38 def migrate_shards(shard_map) source_shards = Set[] target_shards = Hash.new([]) shard_map.each do |(shard, target_shard)| shard = ::Switchman::Shard.find(shard) unless shard.is_a?(::Switchman::Shard) source_shards << shard.delayed_jobs_shard.id target_shard = target_shard.try(:id) || target_shard target_shards[target_shard] += [shard.id] @validation_callbacks&.each do |proc| proc.call(shard: shard, target_shard: ::Switchman::Shard.find(target_shard)) end end # Do the updates in batches and then just clear redis instead of clearing them one at a time target_shards.each do |target_shard, shards| updates = { delayed_jobs_shard_id: target_shard, block_stranded: true } updates[:updated_at] = Time.zone.now if ::Switchman::Shard.column_names.include?("updated_at") ::Switchman::Shard.where(id: shards).update_all(updates) end clear_shard_cache(default: ::Switchman::Shard.exists?(id: target_shards.values.flatten, default: true)) ::Switchman::Shard.clear_cache # rubocop:disable Style/CombinableLoops # We first migrate strands so that we can stop blocking strands before we migrate unstranded jobs source_shards.each do |s| ::Switchman::Shard.lookup(s).activate(::Delayed::Backend::ActiveRecord::AbstractJob) { migrate_strands } end source_shards.each do |s| ::Switchman::Shard.lookup(s).activate(::Delayed::Backend::ActiveRecord::AbstractJob) { migrate_everything } end ensure_unblock_stranded_for(shard_map.map(&:first)) # rubocop:enable Style/CombinableLoops end |
.migrate_strands(batch_size: 1_000) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 120 def migrate_strands(batch_size: 1_000) source_shard = ::Switchman::Shard.current(::Delayed::Backend::ActiveRecord::AbstractJob) # there are 4 scenarios to deal with here # 1) no running job, no jobs moved: do nothing # 2) running job, no jobs moved; create blocker with next_in_strand=false # to prevent new jobs from immediately executing # 3) running job, jobs moved; set next_in_strand=false on the first of # those (= do nothing since it should already be false) # 4) no running job, jobs moved: set next_in_strand=true on the first of # those (= do nothing since it should already be true) handler = lambda { |scope, column, blocker_job_kwargs = {}, advisory_lock_cb = nil| shard_map = build_shard_map(scope, source_shard) shard_map.each do |(target_shard, source_shard_ids)| shard_scope = scope.where(shard_id: source_shard_ids) # 1) is taken care of because it should not show up here in strands values = shard_scope.distinct.order(column).pluck(column) target_shard.activate(::Delayed::Backend::ActiveRecord::AbstractJob) do values.each do |value| transaction_on([source_shard, target_shard]) do source_shard.activate(::Delayed::Backend::ActiveRecord::AbstractJob) do advisory_lock_cb&.call(value) end value_scope = shard_scope.where(**{ column => value }) # we want to copy all the jobs except the one that is still running. jobs_scope = value_scope.where(locked_by: nil) # 2) and part of 3) are taken care of here by creating a blocker # job with next_in_strand = false. as soon as the current # running job is finished it should set next_in_strand # We lock it to ensure that the jobs worker can't delete it until we are done moving the strand # Since we only unlock it on the new jobs queue *after* deleting from the original # the lock ensures the blocker always gets unlocked first = value_scope.where.not(locked_by: nil).next_in_strand_order.lock.first if first create_blocker_job( queue: first.queue, shard_id: first.shard_id, **{ column => value }, **blocker_job_kwargs ) # the rest of 3) is taken care of here # make sure that all the jobs moved over are NOT next in strand ::Delayed::Job.where(next_in_strand: true, locked_by: nil, **{ column => value }) .update_all(next_in_strand: false) end # 4) is taken care of here, by leaving next_in_strand alone and # it should execute on the new shard batch_move_jobs( target_shard: target_shard, source_shard: source_shard, scope: jobs_scope, batch_size: batch_size ) do |job, new_job| # This ensures jobs enqueued on the old jobs shard run before jobs on the new jobs queue new_job.strand_order_override = job.strand_order_override - 1 end end end end end } strand_scope = ::Delayed::Job.shard(source_shard).where.not(strand: nil) singleton_scope = ::Delayed::Job.shard(source_shard).where("strand IS NULL AND singleton IS NOT NULL") all_scope = ::Delayed::Job.shard(source_shard).where("strand IS NOT NULL OR singleton IS NOT NULL") singleton_blocker_additional_kwargs = { locked_at: DateTime.now, locked_by: ::Delayed::Backend::Base::ON_HOLD_BLOCKER } strand_advisory_lock_fn = lambda do |value| acquire_advisory_lock(:strand, value) end singleton_advisory_lock_fn = lambda do |value| acquire_advisory_lock(:singleton, value) end handler.call(strand_scope, :strand, {}, strand_advisory_lock_fn) handler.call(singleton_scope, :singleton, singleton_blocker_additional_kwargs, singleton_advisory_lock_fn) shard_map = build_shard_map(all_scope, source_shard) shard_map.each do |(target_shard, source_shard_ids)| target_shard.activate(::Delayed::Backend::ActiveRecord::AbstractJob) do updated = ::Switchman::Shard.where(id: source_shard_ids, block_stranded: true) .update_all(block_stranded: false) # If this is being manually re-run for some reason to clean something up, don't wait for nothing to happen unless updated.zero? clear_shard_cache("(#{source_shard.id} -> #{target_shard.id})", default: ::Switchman::Shard.exists?(id: source_shard_ids, default: true)) end ::Switchman::Shard.clear_cache # At this time, let's unblock all the strands on the target shard that aren't being held by a blocker # but actually could have run and we just didn't know it because we didn't know if they had jobs # on the source shard unblock_strands(target_shard) end end end |
.run ⇒ Object
This method expects that all relevant shards already have block_stranded: true but otherwise jobs can be running normally
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 113 def run # Ensure this is never run with a dirty in-memory shard cache ::Switchman::Shard.clear_cache migrate_strands migrate_everything end |
.transaction_on(shards, &block) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 24 def transaction_on(shards, &block) return yield if shards.empty? shard = shards.pop current_shard = ::Switchman::Shard.current(::Delayed::Backend::ActiveRecord::AbstractJob) shard.activate(::Delayed::Backend::ActiveRecord::AbstractJob) do ::Delayed::Job.transaction do current_shard.activate(::Delayed::Backend::ActiveRecord::AbstractJob) do transaction_on(shards, &block) end end end end |
.unblock_singleton!(singleton) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 323 def unblock_singleton!(singleton) job_scope = ::Delayed::Job.where(strand: nil, singleton: singleton) raise JobsBlockedError if blocked_by_migrator?(job_scope) ::Delayed::Job.transaction do acquire_advisory_lock(:singleton, singleton) id, next_in_strand = job_scope .group(:singleton) .pick("MIN(id), BOOL_OR(next_in_strand)") if next_in_strand 0 elsif id ::Delayed::Job.where(id: id).update_all(next_in_strand: true) end end end |
.unblock_strand!(strand, new_parallelism: nil) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 293 def unblock_strand!(strand, new_parallelism: nil) job_scope = ::Delayed::Job.where(strand: strand) raise JobsBlockedError if blocked_by_migrator?(job_scope) ::Delayed::Job.transaction do acquire_advisory_lock(:strand, strand) new_parallelism ||= job_scope.pick("MAX(max_concurrent)") if new_parallelism needed_jobs = new_parallelism - job_scope.where(next_in_strand: true).count if needed_jobs.positive? job_scope.where(next_in_strand: false, locked_by: nil, singleton: nil).order(:strand_order_override, :id) .limit(needed_jobs).update_all(next_in_strand: true) else 0 end end end end |
.unblock_strands(target_shard, batch_size: 10_000) ⇒ Object
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# File 'lib/switchman_inst_jobs/jobs_migrator.rb', line 229 def unblock_strands(target_shard, batch_size: 10_000) blocked_shard_ids = blocked_shards.pluck(:id) query = lambda { |column, scope| ::Delayed::Job .where(id: ::Delayed::Job.select("DISTINCT ON (#{column}) id") .where(scope) .where.not(shard_id: blocked_shard_ids) .where( ::Delayed::Job.select(1).from("#{::Delayed::Job.quoted_table_name} dj2") .where("dj2.next_in_strand = true OR dj2.source = 'JobsMigrator::StrandBlocker'") .where("dj2.#{column} = delayed_jobs.#{column}").arel.exists.not ) .order(column, :strand_order_override, :id)).limit(batch_size) } target_shard.activate(::Delayed::Backend::ActiveRecord::AbstractJob) do # We only want to unlock stranded jobs where they don't belong to a blocked shard (if they *do* belong) # to a blocked shard, they must be part of a concurrent jobs migration from a different source shard to # this target shard, so we shouldn't unlock them yet. We only ever unlock one job here to keep the # logic cleaner; if the job is n-stranded, after the first one runs, the trigger will unlock larger # batches loop do break if query.call(:strand, "strand IS NOT NULL").update_all(next_in_strand: true).zero? end loop do break if query.call(:singleton, "strand IS NULL AND singleton IS NOT NULL").update_all(next_in_strand: true).zero? end end end |