Github user nickva commented on a diff in the pull request:
https://github.com/apache/couchdb-couch-replicator/pull/37#discussion_r61345382
--- Diff: src/couch_replicator_manager.erl ---
@@ -124,13 +126,25 @@ replication_error(#rep{id = {BaseId, _} = RepId},
Error) ->
nil ->
ok;
#rep_state{rep = #rep{db_name = DbName, doc_id = DocId}} ->
+ add_error_jitter(),
update_rep_doc(DbName, DocId, [
{<<"_replication_state">>, <<"error">>},
{<<"_replication_state_reason">>,
to_binary(error_reason(Error))},
{<<"_replication_id">>, ?l2b(BaseId)}]),
ok = gen_server:call(?MODULE, {rep_error, RepId, Error}, infinity)
end.
+% Add random delay proportional to the number of replications
+% on current node, in order to prevent a stampede when a source
+% with multiple replication targets fails
+add_error_jitter() ->
+ RepCount = ets:info(?REP_TO_STATE, size),
+ Range = RepCount * 2 * ?AVG_ERROR_DELAY_MSEC,
--- End diff --
Since config macro is called "average error", then made the random uniform
range * 2. For example if need an average of 50, sample from a uniform
interval of 0 to 100.
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