Timeout errors

[andrielfn]

Hi all,

It all started in the Heroku review-envs when we upgraded our application from (Erlang 21.3.7 and Elixir 1.8.2) to (Erlang 22.0.7 and Elixir 1.9.1).
We noticed, for some reason, that downgrading Erlang back to 21.3.7 solved the timeouts.

In this first moment, messages were not being consumed/produced and thousands of timeout errors were flooding the logs. Then we bumped to kafka_ex 0.10, which seemed to have improved a bit (fewer timeouts in the logs and messages being consumed).

However, in the last week, we started to get the same timeouts in production but starting with a lower frequency (~10 timeouts/day).

Some extra information:

• In the Heroku review-envs we use Basic Kafka instances (Multi-Tenant);
• In production, we use a Private Standard Kafka instance;
• We currently have 28 topics created;

I also tried the kafka_ex on the master branch and with the new kayrock API, but seems that it didn't help. Lots of timeouts keep flooding the logs.

The error on 0.10:

2019-11-22T22:25:24.679435+00:00 app[web.1]: 22:25:24.672 [error] GenServer #PID<0.2066.0> terminating
2019-11-22T22:25:24.679445+00:00 app[web.1]: ** (MatchError) no match of right hand side value: :timeout
2019-11-22T22:25:24.679448+00:00 app[web.1]: (kafka_ex) lib/kafka_ex/gen_consumer.ex:678: KafkaEx.GenConsumer.consume/1
2019-11-22T22:25:24.679450+00:00 app[web.1]: (kafka_ex) lib/kafka_ex/gen_consumer.ex:630: KafkaEx.GenConsumer.handle_info/2
2019-11-22T22:25:24.679452+00:00 app[web.1]: (stdlib) gen_server.erl:637: :gen_server.try_dispatch/4
2019-11-22T22:25:24.679454+00:00 app[web.1]: (stdlib) gen_server.erl:711: :gen_server.handle_msg/6
2019-11-22T22:25:24.679458+00:00 app[web.1]: (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
2019-11-22T22:25:24.679461+00:00 app[web.1]: Last message: :timeout
2019-11-22T22:25:24.679465+00:00 app[web.1]: State: %KafkaEx.GenConsumer.State{acked_offset: 0, auto_offset_reset: :earliest, commit_interval: 5000, commit_threshold: 500, committed_offset: 0, consumer_module: FOO.Consumer, consumer_state: nil, current_offset: 0, fetch_options: [auto_commit: false, worker_name: #PID<0.2289.0>], group: "foo.xxx.yyy", last_commit: -576460703586, partition: 0, topic: "bar.baz.bla", worker_name: #PID<0.2289.0>}

And the error now with master:

2019-11-28T19:30:08.763137+00:00 app[web.1]: 19:30:08.762 [debug] Successfully connected to broker "xxxxxxxxx.amazonaws.com":9096
2019-11-28T19:30:08.816252+00:00 app[web.1]: 19:30:08.815 [debug] Successfully connected to broker "xxxxxxxxx.amazonaws.com":9096
2019-11-28T19:30:08.863527+00:00 app[web.1]: 19:30:08.863 [error] Receiving data from broker "xxxxxxxxx.amazonaws.com":9096 failed with :timeout
2019-11-28T19:30:08.869546+00:00 app[web.1]: 19:30:08.869 [debug] Successfully connected to broker "xxxxxxxxx.amazonaws.com":9096
2019-11-28T19:30:08.879048+00:00 app[web.1]: 19:30:08.878 [error] GenServer #PID<0.9105.93> terminating
2019-11-28T19:30:08.879052+00:00 app[web.1]: ** (stop) {:error, :timeout}
2019-11-28T19:30:08.879053+00:00 app[web.1]: Last message: :timeout
2019-11-28T19:30:08.879063+00:00 app[web.1]: State: %KafkaEx.GenConsumer.State{acked_offset: 0, api_versions: %{fetch: 0, offset_commit: 0, offset_fetch: 0}, auto_offset_reset: :earliest, commit_interval: 5000, commit_threshold: 500, committed_offset: 0, consumer_module: FOO.Consumer, consumer_state: nil, current_offset: 0, fetch_options: [auto_commit: false, worker_name: #PID<0.19074.91>], generation_id: 136, group: "foo-51686.foo_service", last_commit: -576424651131, member_id: "kafka_ex-fe6cdc27-cf12-4c45-9beb-76fcc2a1cdf8", partition: 0, topic: "foo.zzz.yyy", worker_name: #PID<0.19074.91>}
2019-11-28T19:30:08.926883+00:00 app[web.1]: 19:30:08.926 [debug] Successfully connected to broker "xxxxxxxxx.amazonaws.com":9096
2019-11-28T19:30:08.971555+00:00 app[web.1]: 19:30:08.971 [debug] Successfully connected to broker "xxxxxxxxx.amazonaws.com":9096

The Successfully connected... and Receiving data from broker... messages are also logged indefinitely, many per second.

[joshuawscott]

I would try increasing the sync_timeout setting if you haven't already. It defaults to 5000 (ms), but I would recommend setting it higher, say 15_000.

[andrielfn]

Hey @joshrotenberg, I forgot to mention but increasing the sync_timeout was one of my attempts. I've just tried one more time with 15_000 and the timeouts are still there.

I also noticed this other error that I believe was not happening on 0.10, but not sure if it's related or not:

2019-11-28T21:35:27.891234+00:00 app[web.1]: 21:35:27.888 [debug] Shutting down worker #PID<0.28898.1>, reason: {:function_clause, [{KafkaEx.New.Client, :handle_info, [{:ssl_closed, {:sslsocket, {:gen_tcp, #Port<0.17549>, :tls_connection, :undefined}, [#PID<0.28902.1>, #PID<0.28901.1>]}}, %KafkaEx.New.Client.State{allow_auto_topic_creation: true, api_versions: %{11 => {0, 4}, 39 => {0, 1}, 34 => {0, 1}, 26 => {0, 1}, 15 => {0, 2}, 20 => {0, 3}, 17 => {0, 1}, 25 => {0, 1}, 13 => {0, 2}, 0 => {0, 7}, 8 => {0, 6}, 36 => {0, 1}, 7 => {0, 2}, 1 => {0, 10}, 32 => {0, 2}, 37 => {0, 1}, 35 => {0, 1}, 3 => {0, 7}, 6 => {0, 5}, 2 => {0, 5}, 41 => {0, 1}, 33 => {0, 1}, 42 => {0, 1}, 43 => {0, 0}, 10 => {0, 2}, 9 => {0, 5}, 19 => {0, 3}, 14 => {0, 2}, 5 => {0, 1}, 18 => {0, 2}, 31 => {0, 1}, 22 => {0, 1}, 29 => {0, 1}, 21 => {0, 1}, 27 => {0, 0}, 24 => {0, 1}, 40 => {0, 1}, 30 => {0, 1}, 23 => {0, ...}, 28 => {...}, ...}, bootstrap_uris: [{"xxxxxxxxx.amazonaws.com", 9096}, {"xxxxxxxxxxxxxxx.amazonaws.com", 9096}, {"xxxxxxxxxxxxxxxxx.amazonaws.com", 9096}, {"xxxxxxxxx.amazonaws.com", 9096}, {"xxxxxxxxx.amazonaws.com", 9096}, {"xxxxxxxxx.amazonaws.com", 9096}, {"xxxxxxxxx.amazonaws.com", 9096}, {"xxxxxxxxx.amazonaws.com", 9096}], cluster_metadata: %KafkaEx.New.ClusterMetadata{brokers: %{0 => %KafkaEx.New.Broker{host: "xxxxxxxxx.amazonaws.com", node_id: 0, port: 9096, rack: "us-east-1e", socket: %KafkaEx.Socket{socket: {:sslsocket, {:gen_tcp, #Port<0.17550>, :tls_connection, :undefined}, [#PID<0.28904.1>, #PID<0.28903.1>]}, ssl: true}}, 1 => %KafkaEx.New.Broker{host: "xxxxxxxxx.amazonaws.com", node_id: 1, port: 9096, rack: "us-east-1c", socket: %KafkaEx.Socket{socket: {:sslsocket, {:gen_tcp, #Port<0.17552>, :tls_connection, :undefined}, [#PID<0.28908.1>, #PID<0.28907.1>]}, ssl: true}}, 2 => %KafkaEx.New.Broker{host: "xxxxxxxxx.amazonaws.com", node_id: 2, port: 9096, rack: "us-east-1e", socket: %KafkaEx.Socket{socket: {:sslsocket, {:gen_tcp, #Port<0.17549>, :tls_connection, :undefined}, [#PID<0.28902.1>, #PID<0.28901.1>]}, ssl: true}}, 3 => %KafkaEx.New.Broker{host: "xxxxxxxxx.amazonaws.com", node_id: 3, port: 9096, rack: "us-east-1a", socket: %KafkaEx.Socket{socket: {:sslsocket, {:gen_tcp, #Port<0.17553>, :tls_connection, :undefined}, [#PID<0.28910.1>, #PID<0.28909.1>]}, ssl: true}}, 5 => %KafkaEx.New.Broker{host: "xxxxxxxxx.amazonaws.com", node_id: 5, port: 9096, rack: "us-east-1d", socket: %KafkaEx.Socket{socket: {:sslsocket, {:gen_tcp, #Port<0.17548>, :tls_connection, :undefined}, [#PID<0.28900.1>, #PID<0.28899.1>]}, ssl: true}}, 6 => %KafkaEx.New.Broker{host: "xxxxxxxxx.amazonaws.com", node_id: 6, port: 9096, rack: "us-east-1d", socket: %KafkaEx.Socket{socket: {:sslsocket, {:gen_tcp, #Port<0.17551>, :tls_connection, :undefined}, [#PID<0.28906.1>, #PID<0.28905.1>]}, ssl: true}}, 7 => %KafkaEx.New.Broker{host: "xxxxxxxxx.amazonaws.com", node_id: 7, port: 9096, rack: "us-east-1c", socket: %KafkaEx.Socket{socket: {:sslsocket, {:gen_tcp, #Port<0.17554>, :tls_connection, :undefined}, [#PID<0.28912.1>, #PID<0.28911.1>]}, ssl: true}}, 8 => %KafkaEx.New.Broker{host: "xxxxxxxxx.amazonaws.com", node_id: 8, port: 9096, rack: "us-east-1a", socket: %KafkaEx.Socket{socket: {:sslsocket, {:gen_tcp, #Port<0.17555>, :tls_connection, :undefined}, [#PID<0.28914.1>, #PID<0.28913.1>]}, ssl: true}}}, consumer_group_coordinators: %{"xxxxx.yyyy" => 7}, controller_id: 7, topics: %{"xxxxx.yyyy.zzzzz" => %KafkaEx.New.Topic{is_internal: 0, name: "xxxxx.yyyy.zzzzz", partition_leaders: %{0 => 7}, partitions: [%KafkaEx.New.Partition{isr: [7, 5, 0], leader: 7, partition_id: 0, replicas: [7, 5, 0]}]}}}, consumer_group_for_auto_commit: "xxxxx.yyyy", consumer_group_update_interval: 30000, correlation_id: 160, metadata_update_interval: 30000, ssl_options: [cert: <<48, 130, 3, 67, 48, 130, 2, 43, 160, 3, 2, 1, 2, 2, 1, 0, 48, 13, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 11, 5, 0, 48, ...>>, key: {:RSAPrivateKey, <<48, 130, 4, 163, 2, 1, 0, 2, 130, 1, 1, 0, 221, 216, 88, 132, 223, 93, 49, 100, 242, 20, 13, 106, 143, 177, 37, 95, 120, ...>>}], use_ssl: true, worker_name: #PID<0.28898.1>}], [file: 'lib/kafka_ex/new/client.ex', line: 179]}, {:gen_server, :try_dispatch, 4, [file: 'gen_server.erl', line: 637]}, {:gen_server, :handle_msg, 6, [file: 'gen_server.erl', line: 711]}, {:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 249]}]}
2019-11-28T21:35:27.913314+00:00 app[web.1]: 21:35:27.899 [error] GenServer #PID<0.28898.1> terminating
2019-11-28T21:35:27.913335+00:00 app[web.1]: ** (FunctionClauseError) no function clause matching in KafkaEx.New.Client.handle_info/2

[dantswain]

Is it possible that the ssl config changed?

Also, would it be possible to try different versions of Erlang? Can you try 22.1?

I vaguely remember running into some ssl-related issues with different erlang versions but I don’t remember the details :(

[andrielfn]

Is it possible that the ssl config changed?

Which config do you mean exactly? But I'd say no, we haven't changed any config in the app nor in the Kafka cluster.

Can you try 22.1?

Actually, we are on the 22.1.6 already. I've just tried the 22.1.8 as well but still the same. And to make sure the Erlang version is somehow related, I downgraded to the initial version and it works perfectly, no timeouts at all.

@ elixir_buildpack.config:1 @
-erlang_version=22.1.8
+erlang_version=21.3.7

[andrielfn]

While the 21.3.7 is working fine, the next closest version (22.0.3) available in the Heroku buildpack is already raising the timeouts, so potentially is something related to the major upgrade.

[dmitry-semenov]

Confirming the issue, we had to downgrade to the same version (21.3.7) to avoid timout issues.
At the time of researching the problem we suspected this change to the OTP https://github.com/erlang/otp/pull/2224/files to be the root cause.

[Argonus]

Hi, any news with that?
@joshuawscott

[jbruggem]

FYI, I created an issue on the OTP project.

https://bugs.erlang.org/browse/ERL-1213

I'm not sure what we can really do in the mean time, we can try silently re-create a socket every time there's a timeout, but that sounds like a bad idea.

[jbruggem]

I tested many versions of OTP. The problem appears in OTP 21.3. With OTP 21.2 and lower, things are fine:

https://github.com/jbruggem/kafka_ex_ssl_bug#run-many-times

[dantswain]

Thank you for following up on this so thoroughly!

[dantswain]

@jbruggem whats the conclusion here? I’ll get kayrock patched ASAP but my understanding was that’s not the bug but rather a compilation problem you discovered while hunting the bug.