[KAFKA-6503] Connect: Plugin scan is very slow

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.0.0
• Fix Version/s: 1.1.0, 2.0.0
• Component/s: connect
• Assignee: Robert Yokota
• Reporter: Per Steffensen
• Created: 30/Jan/18 14:20
• Updated: 25/Apr/18 09:42
• Resolved: 15/Feb/18 00:25

Description

Just upgraded to 1.0.0. It seems some plugin scan has been introduced. It is very slow - see logs from starting my Kafka-Connect instance at the bottom. It takes almost 4 minutes scanning. I am running Kafka-Connect in docker based on confluentinc/cp-kafka-connect:4.0.0. I set plugin.path to /usr/share/java. The only thing I have added is a 13MB jar in /usr/share/java/kafka-connect-file-streamer-client containing two connectors and a converter. That one alone seems to take 20 secs.

If it was just scanning in the background, and everything was working it probably would not be a big issue. But it does not. Right after starting the Kafka-Connect instance I try to create a connector via the /connectors endpoint, but it will not succeed before the plugin scanning has finished (4 minutes)

I am not even sure why scanning is necessary. Is it not always true that connectors, converters etc are mentioned by name, so to see if it exists, just try to load the class - the classloader will tell if it is available. Hmmm, there is probably a reason.

Anyway, either it should be made much faster, or at least Kafka-Connect should be fully functional (or as functional as possible) while scanning is going on.

[2018-01-30 13:52:26,834] INFO Scanning for plugin classes. This might take a moment ... (org.apache.kafka.connect.cli.ConnectDistributed)
[2018-01-30 13:52:27,218] INFO Loading plugin from: /usr/share/java/kafka-connect-file-streamer-client (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:43,037] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/kafka-connect-file-streamer-client/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:43,038] INFO Added plugin 'com.tlt.common.files.streamer.client.kafka.connect.OneTaskPerStreamSourceConnectorManager' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:43,039] INFO Added plugin 'com.tlt.common.files.streamer.client.kafka.connect.OneTaskPerFilesStreamerServerSourceConnectorManager' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:43,040] INFO Added plugin 'com.tlt.common.files.streamer.client.kafka.connect.KafkaConnectByteArrayConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:43,049] INFO Loading plugin from: /usr/share/java/kafka-connect-elasticsearch (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:47,595] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/kafka-connect-elasticsearch/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:47,611] INFO Added plugin 'io.confluent.connect.elasticsearch.ElasticsearchSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:47,651] INFO Loading plugin from: /usr/share/java/kafka-connect-jdbc (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:49,491] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/kafka-connect-jdbc/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:49,491] INFO Added plugin 'io.confluent.connect.jdbc.JdbcSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:49,492] INFO Added plugin 'io.confluent.connect.jdbc.JdbcSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:52:49,663] INFO Loading plugin from: /usr/share/java/kafka-connect-s3 (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:53:51,055] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/kafka-connect-s3/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:53:51,055] INFO Added plugin 'io.confluent.connect.s3.S3SinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:53:51,061] INFO Added plugin 'io.confluent.connect.storage.tools.SchemaSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:53:51,064] INFO Added plugin 'io.confluent.connect.avro.AvroConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:53:52,745] INFO Loading plugin from: /usr/share/java/kafka-connect-storage-common (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:54:25,800] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/kafka-connect-storage-common/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:54:26,402] INFO Loading plugin from: /usr/share/java/kafka-connect-hdfs (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:54:58,104] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/kafka-connect-hdfs/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:54:58,104] INFO Added plugin 'io.confluent.connect.hdfs.tools.SchemaSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:54:58,104] INFO Added plugin 'io.confluent.connect.hdfs.HdfsSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:54:58,508] INFO Loading plugin from: /usr/share/java/monitoring-interceptors (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:00,714] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/monitoring-interceptors/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:00,715] INFO Loading plugin from: /usr/share/java/kafka-serde-tools (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:03,900] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/kafka-serde-tools/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:03,911] INFO Loading plugin from: /usr/share/java/confluent-rebalancer (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:11,702] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/confluent-rebalancer/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:11,722] INFO Loading plugin from: /usr/share/java/confluent-control-center (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,874] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/confluent-control-center/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,875] INFO Added plugin 'org.apache.kafka.connect.tools.MockSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,875] INFO Added plugin 'org.apache.kafka.connect.tools.SchemaSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,876] INFO Added plugin 'org.apache.kafka.connect.tools.MockConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,876] INFO Added plugin 'org.apache.kafka.connect.tools.MockSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,876] INFO Added plugin 'org.apache.kafka.connect.tools.VerifiableSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,877] INFO Added plugin 'org.apache.kafka.connect.tools.VerifiableSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,878] INFO Added plugin 'org.apache.kafka.connect.converters.ByteArrayConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,878] INFO Added plugin 'org.apache.kafka.connect.storage.StringConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,879] INFO Added plugin 'org.apache.kafka.connect.json.JsonConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,879] INFO Added plugin 'org.apache.kafka.connect.transforms.Cast$Value' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,879] INFO Added plugin 'org.apache.kafka.connect.transforms.Flatten$Key' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,880] INFO Added plugin 'org.apache.kafka.connect.transforms.TimestampConverter$Value' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,880] INFO Added plugin 'org.apache.kafka.connect.transforms.Cast$Key' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,881] INFO Added plugin 'org.apache.kafka.connect.transforms.MaskField$Value' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,881] INFO Added plugin 'org.apache.kafka.connect.transforms.TimestampRouter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,882] INFO Added plugin 'org.apache.kafka.connect.transforms.ExtractField$Value' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,882] INFO Added plugin 'org.apache.kafka.connect.transforms.TimestampConverter$Key' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,896] INFO Added plugin 'org.apache.kafka.connect.transforms.MaskField$Key' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,904] INFO Added plugin 'org.apache.kafka.connect.transforms.ExtractField$Key' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,904] INFO Added plugin 'org.apache.kafka.connect.transforms.Flatten$Value' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,905] INFO Added plugin 'org.apache.kafka.connect.transforms.ValueToKey' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,905] INFO Added plugin 'org.apache.kafka.connect.transforms.HoistField$Value' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,905] INFO Added plugin 'org.apache.kafka.connect.transforms.HoistField$Key' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,906] INFO Added plugin 'org.apache.kafka.connect.transforms.ReplaceField$Value' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,914] INFO Added plugin 'org.apache.kafka.connect.transforms.InsertField$Key' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,914] INFO Added plugin 'org.apache.kafka.connect.transforms.InsertField$Value' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,915] INFO Added plugin 'org.apache.kafka.connect.transforms.SetSchemaMetadata$Value' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,915] INFO Added plugin 'org.apache.kafka.connect.transforms.RegexRouter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,915] INFO Added plugin 'org.apache.kafka.connect.transforms.SetSchemaMetadata$Key' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,915] INFO Added plugin 'org.apache.kafka.connect.transforms.ReplaceField$Key' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:21,919] INFO Loading plugin from: /usr/share/java/confluent-common (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:23,165] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/confluent-common/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:23,175] INFO Loading plugin from: /usr/share/java/kafka (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:41,996] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/kafka/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:41,997] INFO Added plugin 'org.apache.kafka.connect.file.FileStreamSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:41,998] INFO Added plugin 'org.apache.kafka.connect.file.FileStreamSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:42,021] INFO Loading plugin from: /usr/share/java/confluent-serializers (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:44,081] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/confluent-serializers/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:44,089] INFO Loading plugin from: /usr/share/java/schema-registry (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:49,504] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/schema-registry/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:49,541] INFO Loading plugin from: /usr/share/java/rest-utils (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:55:52,094] INFO Registered loader: PluginClassLoader{pluginLocation=file:/usr/share/java/rest-utils/} (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,632] INFO Registered loader: sun.misc.Launcher$AppClassLoader@18b4aac2 (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,659] INFO Added aliases 'OneTaskPerFilesStreamerServerSourceConnectorManager' and 'OneTaskPerFilesStreamerServerSource' to plugin 'com.tlt.common.files.streamer.client.kafka.connect.OneTaskPerFilesStreamerServerSourceConnectorManager' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,663] INFO Added aliases 'OneTaskPerStreamSourceConnectorManager' and 'OneTaskPerStreamSource' to plugin 'com.tlt.common.files.streamer.client.kafka.connect.OneTaskPerStreamSourceConnectorManager' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,665] INFO Added aliases 'ElasticsearchSinkConnector' and 'ElasticsearchSink' to plugin 'io.confluent.connect.elasticsearch.ElasticsearchSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,667] INFO Added aliases 'HdfsSinkConnector' and 'HdfsSink' to plugin 'io.confluent.connect.hdfs.HdfsSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,668] INFO Added aliases 'JdbcSinkConnector' and 'JdbcSink' to plugin 'io.confluent.connect.jdbc.JdbcSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,670] INFO Added aliases 'JdbcSourceConnector' and 'JdbcSource' to plugin 'io.confluent.connect.jdbc.JdbcSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,672] INFO Added aliases 'S3SinkConnector' and 'S3Sink' to plugin 'io.confluent.connect.s3.S3SinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,673] INFO Added aliases 'FileStreamSinkConnector' and 'FileStreamSink' to plugin 'org.apache.kafka.connect.file.FileStreamSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,695] INFO Added aliases 'FileStreamSourceConnector' and 'FileStreamSource' to plugin 'org.apache.kafka.connect.file.FileStreamSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,697] INFO Added aliases 'MockConnector' and 'Mock' to plugin 'org.apache.kafka.connect.tools.MockConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,699] INFO Added aliases 'MockSinkConnector' and 'MockSink' to plugin 'org.apache.kafka.connect.tools.MockSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,700] INFO Added aliases 'MockSourceConnector' and 'MockSource' to plugin 'org.apache.kafka.connect.tools.MockSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,702] INFO Added aliases 'VerifiableSinkConnector' and 'VerifiableSink' to plugin 'org.apache.kafka.connect.tools.VerifiableSinkConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,705] INFO Added aliases 'VerifiableSourceConnector' and 'VerifiableSource' to plugin 'org.apache.kafka.connect.tools.VerifiableSourceConnector' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,706] INFO Added aliases 'KafkaConnectByteArrayConverter' and 'KafkaConnectByteArray' to plugin 'com.tlt.common.files.streamer.client.kafka.connect.KafkaConnectByteArrayConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,711] INFO Added aliases 'AvroConverter' and 'Avro' to plugin 'io.confluent.connect.avro.AvroConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,711] INFO Added aliases 'ByteArrayConverter' and 'ByteArray' to plugin 'org.apache.kafka.connect.converters.ByteArrayConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,715] INFO Added aliases 'JsonConverter' and 'Json' to plugin 'org.apache.kafka.connect.json.JsonConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,715] INFO Added aliases 'StringConverter' and 'String' to plugin 'org.apache.kafka.connect.storage.StringConverter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,727] INFO Added alias 'RegexRouter' to plugin 'org.apache.kafka.connect.transforms.RegexRouter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,738] INFO Added alias 'TimestampRouter' to plugin 'org.apache.kafka.connect.transforms.TimestampRouter' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)
[2018-01-30 13:56:14,739] INFO Added alias 'ValueToKey' to plugin 'org.apache.kafka.connect.transforms.ValueToKey' (org.apache.kafka.connect.runtime.isolation.DelegatingClassLoader)

Issue Links

• relates to: KAFKA-6208 Reduce startup time for Kafka Connect workers
• links to: GitHub Pull Request #4561