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author | Benjamin Anderson <b@banjiewen.net> | 2014-10-29 12:52:30 -0700 |
---|---|---|
committer | Eric Avdey <eiri@eiri.ca> | 2016-11-24 13:55:18 -0400 |
commit | c4da61c8eb98cedd3cf7a28c293cb1f6d3ec8571 (patch) | |
tree | 567dec1b0f2135b1b8ae662f9aba3a343496bce7 | |
parent | 252467cb4a27637090b5f9006483f5b7ab551699 (diff) | |
download | couchdb-c4da61c8eb98cedd3cf7a28c293cb1f6d3ec8571.tar.gz |
Chunk missing revisions before attempting to save on target
In cases with pathological documents revision patterns (e.g., 10000 open
conflicts and tree depth of 300000 on a single document), attempting to
replicate the full revision tree in one batch causes the system to crash by
attempting to send an oversized message. We've observed messages of > 4GB in the
wild.
This patch divides the set of revisions-to-replicate for a single document into
chunks of a configurable size, thereby allowing operators to keep the system
stable when attempting to replicate these troublesome documents.
BugzID: 37676
-rw-r--r-- | src/mem3_rep.erl | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/src/mem3_rep.erl b/src/mem3_rep.erl index 938260da6..ad7ac55f5 100644 --- a/src/mem3_rep.erl +++ b/src/mem3_rep.erl @@ -252,8 +252,10 @@ replicate_batch(#acc{target = #shard{node=Node, name=Name}} = Acc) -> [] -> ok; Missing -> - Docs = open_docs(Acc, Missing), - ok = save_on_target(Node, Name, Docs) + lists:map(fun(Chunk) -> + Docs = open_docs(Acc, Chunk), + ok = save_on_target(Node, Name, Docs) + end, chunk_revs(Missing)) end, update_locals(Acc), {ok, Acc#acc{revcount=0, infos=[]}}. @@ -271,6 +273,32 @@ find_missing_revs(Acc) -> ]). +chunk_revs(Revs) -> + Limit = list_to_integer(config:get("mem3", "rev_chunk_size", "5000")), + chunk_revs(Revs, Limit). + +chunk_revs(Revs, Limit) -> + chunk_revs(Revs, {0, []}, [], Limit). + +chunk_revs([], {_Count, Chunk}, Chunks, _Limit) -> + [Chunk|Chunks]; +chunk_revs([{Id, R, A}|Revs], {Count, Chunk}, Chunks, Limit) when length(R) =< Limit - Count -> + chunk_revs( + Revs, + {Count + length(R), [{Id, R, A}|Chunk]}, + Chunks, + Limit + ); +chunk_revs([{Id, R, A}|Revs], {Count, Chunk}, Chunks, Limit) -> + {This, Next} = lists:split(Limit - Count, R), + chunk_revs( + [{Id, Next, A}|Revs], + {0, []}, + [[{Id, This, A}|Chunk]|Chunks], + Limit + ). + + open_docs(#acc{source=Source, infos=Infos}, Missing) -> lists:flatmap(fun({Id, Revs, _}) -> FDI = lists:keyfind(Id, #full_doc_info.id, Infos), |