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rabbit_quorum_queue: Shrink batches of QQs in parallel #15081

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rabbit_quorum_queue: Shrink batches of QQs in parallel #15081

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97 changes: 64 additions & 33 deletions deps/rabbit/src/rabbit_quorum_queue.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -1492,39 +1492,70 @@ delete_member(Q, Node) when ?amqqueue_is_quorum(Q) ->
{ok, pos_integer()} | {error, pos_integer(), term()}}].
shrink_all(Node) ->
?LOG_INFO("Asked to remove all quorum queue replicas from node ~ts", [Node]),
[begin
QName = amqqueue:get_name(Q),
?LOG_INFO("~ts: removing member (replica) on node ~w",
[rabbit_misc:rs(QName), Node]),
Size = length(get_nodes(Q)),
case delete_member(Q, Node) of
ok ->
{QName, {ok, Size-1}};
{error, cluster_change_not_permitted} ->
%% this could be timing related and due to a new leader just being
%% elected but it's noop command not been committed yet.
%% lets sleep and retry once
?LOG_INFO("~ts: failed to remove member (replica) on node ~w "
"as cluster change is not permitted. "
"retrying once in 500ms",
[rabbit_misc:rs(QName), Node]),
timer:sleep(500),
case delete_member(Q, Node) of
ok ->
{QName, {ok, Size-1}};
{error, Err} ->
?LOG_WARNING("~ts: failed to remove member (replica) on node ~w, error: ~w",
[rabbit_misc:rs(QName), Node, Err]),
{QName, {error, Size, Err}}
end;
{error, Err} ->
?LOG_WARNING("~ts: failed to remove member (replica) on node ~w, error: ~w",
[rabbit_misc:rs(QName), Node, Err]),
{QName, {error, Size, Err}}
end
end || Q <- rabbit_amqqueue:list(),
amqqueue:get_type(Q) == ?MODULE,
lists:member(Node, get_nodes(Q))].
%% This operation is bound by I/O so this default is set high.
Size = application:get_env(rabbit, quorum_queue_shrink_batch_size, 64),
Chunks = ra_lib:lists_chunk(Size, [Q || Q <- rabbit_amqqueue:list(),
amqqueue:get_type(Q) == ?MODULE,
lists:member(Node, get_nodes(Q))]),
Parent = self(),
lists:flatten([begin
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@kjnilsson kjnilsson Jan 13, 2026

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could you use ra_lib:partition_parallel/2|3 here?

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@the-mikedavis the-mikedavis Jan 13, 2026 •
edited
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Not directly: shrink/2 returns the current or updated size of the cluster and that's used in the output of the rabbitmq-queues shrink command. With ra_lib:partition_parallel/2 we need to return a boolean so we can't add the size info. Implementation-wise though, this looks nearly the same.

Tasks = [{spawn_monitor(fun() ->
Res = shrink(Node, Q),
Parent ! {self(), Res}
end), amqqueue:get_name(Q)}
|| Q <- Chunk],
[receive
{Pid, Res} ->
erlang:demonitor(MRef, [flush]),
{QName, Res};
{'DOWN', MRef, process, Pid, Reason} ->
?LOG_WARNING("~ts: failed to remove member "
"(replica) on node ~w, error: ~w",
[rabbit_misc:rs(QName), Node,
Reason]),
[]
after
15_000 ->
?LOG_WARNING("~ts: failed to remove member "
"(replica) on node ~w within 15 "
"seconds",
[rabbit_misc:rs(QName), Node]),
[]
end || {{Pid, MRef}, QName} <- Tasks]
end || Chunk <- Chunks]).

-spec shrink(node(), amqqueue:amqqueue()) ->
{ok, Size} | {error, Size, term()} when Size :: pos_integer().
shrink(Node, Q) ->
QName = amqqueue:get_name(Q),
?LOG_INFO("~ts: removing member (replica) on node ~w",
[rabbit_misc:rs(QName), Node]),
Size = length(get_nodes(Q)),
case delete_member(Q, Node) of
ok ->
{ok, Size-1};
{error, cluster_change_not_permitted} ->
%% this could be timing related and due to a new leader just being
%% elected but it's noop command not been committed yet.
%% lets sleep and retry once
?LOG_INFO("~ts: failed to remove member (replica) on node ~w "
"as cluster change is not permitted. "
"retrying once in 500ms",
[rabbit_misc:rs(QName), Node]),
timer:sleep(500),
case delete_member(Q, Node) of
ok ->
{ok, Size-1};
{error, Err} ->
?LOG_WARNING("~ts: failed to remove member (replica) on node ~w, error: ~w",
[rabbit_misc:rs(QName), Node, Err]),
{error, Size, Err}
end;
{error, Err} ->
?LOG_WARNING("~ts: failed to remove member (replica) on node ~w, error: ~w",
[rabbit_misc:rs(QName), Node, Err]),
{error, Size, Err}
end.

-spec grow(node() | integer(), binary(), binary(), all | even) ->
[{rabbit_amqqueue:name(),
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