Migrate queues in batches of 100 in parallel. Write recovery terms for migrated queues.

Author: Daniil Fedotov

src/rabbit_queue_index.erl

@@ -26,7 +26,7 @@
 -export([scan_queue_segments/3]).
 
 %% Migrates from global to per-vhost message stores
--export([move_to_per_vhost_stores/1]).
+-export([move_to_per_vhost_stores/1, update_recovery_term/2]).
 
 -define(CLEAN_FILENAME, "clean.dot").
 
@@ -1419,3 +1419,7 @@ move_to_per_vhost_stores(#resource{} = QueueName) ->
                             [QueueName])
     end,
     ok.
+
+update_recovery_term(#resource{} = QueueName, Term) ->
+    Key = queue_name_to_dir_name(QueueName),
+    rabbit_recovery_terms:store(Key, Term).

src/rabbit_variable_queue.erl

@@ -37,6 +37,8 @@
 -export([stop_vhost_msg_store/1]).
 -include_lib("stdlib/include/qlc.hrl").
 
+-define(QUEUE_MIGRATION_BATCH_SIZE, 100).
+
 %%----------------------------------------------------------------------------
 %% Messages, and their position in the queue, can be in memory or on
 %% disk, or both. Persistent messages will have both message and
@@ -351,7 +353,7 @@
 %%----------------------------------------------------------------------------
 
 -rabbit_upgrade({multiple_routing_keys, local, []}).
--rabbit_upgrade({move_messages_to_vhost_store, queues, []}).
+-rabbit_upgrade({move_messages_to_vhost_store, message_store, []}).
 
 -compile(export_all).
 
@@ -2716,7 +2718,7 @@ move_messages_to_vhost_store() ->
     rabbit_log:info("Moving messages to per-vhost message store"),
     Queues = list_persistent_queues(),
     %% Move the queue index for each persistent queue to the new store
-    lists:map(
+    lists:foreach(
         fun(Queue) ->
             #amqqueue{name = QueueName} = Queue,
             rabbit_queue_index:move_to_per_vhost_stores(QueueName)
@@ -2725,39 +2727,49 @@ move_messages_to_vhost_store() ->
     %% Legacy (global) msg_store may require recovery.
     %% This upgrade step should only be started
     %% if we are upgrading from a pre-3.7.0 version.
-    {RecoveryTerms, StartFunState} = start_recovery_terms(Queues),
-    OldStore = run_old_persistent_store(RecoveryTerms, StartFunState),
+    {QueuesWithTerms, RecoveryRefs, StartFunState} = start_recovery_terms(Queues),
+
+    OldStore = run_old_persistent_store(RecoveryRefs, StartFunState),
     %% New store should not be recovered.
     NewStoreSup = start_new_store_sup(),
+    in_batches(?QUEUE_MIGRATION_BATCH_SIZE,
+        {rabbit_variable_queue, migrate_queue, [OldStore, NewStoreSup]},
+        QueuesWithTerms),
 
-    % {ok, Gatherer} = gatherer:start_link(),
-    lists:map(
-        fun(Queue) ->
-            migrate_queue(Queue, OldStore, NewStoreSup),
-            #amqqueue{name = QueueName} = Queue,
-            rabbit_log:info("Queue migration finished ~p", [QueueName])
-            % ok = gatherer:fork(Gatherer),
-            % ok = worker_pool:submit_async(
-            %     fun () ->
-            %             migrate_queue(Queue, OldStore, NewStoreSup),
-            %             gatherer:finish(Gatherer)
-            %     end)
-        end,
-        Queues),
-    % empty = gatherer:out(Gatherer),
-    % ok = gatherer:stop(Gatherer),
-
+    rabbit_log:info("Message store migration finished"),
     delete_old_store(OldStore),
 
     ok = rabbit_queue_index:stop(),
-    ok = rabbit_sup:stop_child(NewStoreSup).
+    ok = rabbit_sup:stop_child(NewStoreSup),
+    ok.
 
-migrate_queue(Queue, OldStore, NewStoreSup) ->
-    #amqqueue{name = QueueName} = Queue,
+in_batches(Size, MFA, List) ->
+    in_batches(Size, 1, MFA, List).
+
+in_batches(_, _, _, []) -> ok;
+in_batches(Size, BatchNum, MFA, List) ->
+    {Batch, Tail} = case Size > length(List) of
+        true  -> {List, []};
+        false -> lists:split(Size, List)
+    end,
+    rabbit_log:info("Migrating batch ~p of ~p queues ~n", [BatchNum, Size]),
+    {M, F, A} = MFA,
+    Keys = [ rpc:async_call(node(), M, F, [El | A]) || El <- Batch ],
+    lists:foreach(fun(Key) ->
+        case rpc:yield(Key) of
+            {badrpc, Err} -> throw(Err);
+            _             -> ok
+        end
+    end,
+    Keys),
+    rabbit_log:info("Batch ~p of ~p queues migrated ~n", [BatchNum, Size]),
+    in_batches(Size, BatchNum + 1, MFA, Tail).
+
+migrate_queue({QueueName, RecoveryTerm}, OldStore, NewStoreSup) ->
     rabbit_log:info("Migrating messages in queue ~s in vhost ~s to per-vhost message store~n",
       [QueueName#resource.name, QueueName#resource.virtual_host]),
     OldStoreClient = get_global_store_client(OldStore),
-    NewStoreClient = get_per_vhost_store_client(Queue, NewStoreSup),
+    NewStoreClient = get_per_vhost_store_client(QueueName, NewStoreSup),
     %% WARNING: During scan_queue_segments queue index state is being recovered
     %% and terminated. This can cause side effects!
     rabbit_queue_index:scan_queue_segments(
@@ -2771,23 +2783,25 @@ migrate_queue(Queue, OldStore, NewStoreSup) ->
                 OldC
         end,
         OldStoreClient,
-        QueueName).
+        QueueName),
+    rabbit_msg_store:client_terminate(OldStoreClient),
+    rabbit_msg_store:client_terminate(NewStoreClient),
+    NewClientRef = rabbit_msg_store:client_ref(NewStoreClient),
+    NewRecoveryTerm = lists:keyreplace(persistent_ref, 1, RecoveryTerm,
+                                       {persistent_ref, NewClientRef}),
+    rabbit_queue_index:update_recovery_term(QueueName, NewRecoveryTerm),
+    rabbit_log:info("Queue migration finished ~p", [QueueName]),
+    {QueueName, NewClientRef}.
 
 migrate_message(MsgId, OldC, NewC) ->
     case rabbit_msg_store:read(MsgId, OldC) of
         {{ok, Msg}, OldC1} ->
-            case rabbit_msg_store:contains(MsgId, NewC) of
-                false -> ok = rabbit_msg_store:write(MsgId, Msg, NewC);
-                true  -> ok
-            end,
-            % TODO: maybe remove in batches?
-            ok = rabbit_msg_store:remove([MsgId], OldC1),
+            ok = rabbit_msg_store:write(MsgId, Msg, NewC),
             OldC1;
         _ -> OldC
     end.
 
-get_per_vhost_store_client(#amqqueue{name = #resource{virtual_host = VHost}},
-                           NewStoreSup) ->
+get_per_vhost_store_client(#resource{virtual_host = VHost}, NewStoreSup) ->
     rabbit_msg_store_vhost_sup:client_init(NewStoreSup,
                                            rabbit_guid:gen(),
                                            fun(_,_) -> ok end,
@@ -2820,7 +2834,7 @@ start_recovery_terms(Queues) ->
                        Ref = proplists:get_value(persistent_ref, Terms),
                        Ref =/= undefined
                    end],
-    {Refs, StartFunState}.
+    {lists:zip(QueueNames, AllTerms), Refs, StartFunState}.
 
 run_old_persistent_store(Refs, StartFunState) ->
     OldStoreName = ?PERSISTENT_MSG_STORE,