Github user nickva commented on a diff in the pull request:
https://github.com/apache/couchdb-couch-replicator/pull/40#discussion_r64961411
--- Diff: src/couch_replicator_httpc.erl ---
@@ -251,18 +257,42 @@ clean_mailbox(_, Count) when Count > 0 ->
maybe_retry(Error, Worker, #httpdb{retries = 0} = HttpDb, Params) ->
report_error(Worker, HttpDb, Params, {error, Error});
+%% For 429 errors, we perform an exponential backoff up to 250 * 2^15
+%% times, or roughly 2.17 hours. Since the #httpd.retries is initialized
+%% to 10 and we need 15, we use the Wait time as a timeout/failure end.
+maybe_retry(backoff, Worker, #httpdb{wait = Wait} = HttpDb, Params) ->
+ ok = timer:sleep(random:uniform(Wait)),
+ Wait2 = Wait*2,
+ case Wait2 of
+ W0 when W0 >= 512000 -> % Past 8 min, we log retries
+ log_retry_error(Params, HttpDb, Wait, "429 Retry");
+ W1 when W1 > ?MAX_BACKOFF_WAIT ->
+ report_error(Worker, HttpDb, Params, {error,
+ "429 Retry Timeout"});
+ _ ->
+ NewWait = erlang:min(Wait2, ?MAX_BACKOFF_WAIT),
+ NewHttpDb = HttpDb#httpdb{wait = NewWait},
+ throw({retry, NewHttpDb, Params})
+ end;
+
maybe_retry(Error, _Worker, #httpdb{retries = Retries, wait = Wait} =
HttpDb,
Params) ->
- Method = string:to_upper(atom_to_list(get_value(method, Params, get))),
- Url = couch_util:url_strip_password(full_url(HttpDb, Params)),
- couch_log:notice("Retrying ~s request to ~s in ~p seconds due to error
~s",
- [Method, Url, Wait / 1000, error_cause(Error)]),
- ok = timer:sleep(Wait),
+ log_retry_error(Params, HttpDb, Wait, Error),
+ % This is so that a long backoff time is not used to ensure
+ % backwards compatibility.
+ ok = timer:sleep(erlang:min(Wait, ?MAX_WAIT)),
Wait2 = erlang:min(Wait * 2, ?MAX_WAIT),
--- End diff --
Let's randomize this as well, it avoids global synchronization (having all
replication back-off with the same schedule).
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