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apache / samza / 4ad502f67470c74c98be0c8f9a884a05ade28483
commit4ad502f67470c74c98be0c8f9a884a05ade28483[log] [tgz]
authorHai Lu <halu@linkedin.com>Sat Nov 21 17:02:50 2020 -0800
committerGitHub <noreply@github.com>Sat Nov 21 17:02:50 2020 -0800
treec7a8b12c7aaf20c396ab59afc45f79cf36acbdd6
parentf2b10e069510bac3baba7f70ec8486b77ba0a05f [diff]
parenta58125bb57071996a698370e260419a2a403d0d4 [diff]
SAMZA-2601: avoid infinite loop when resource not allocated with host affinity disabled (#1441)

Problem: If YARN does not immediately allocate resources for a container and host affinity is disabled for the job, then the container allocator will spam the logs with messages about the request, even if the request is considered expired. This is because the allocator loops over the pending requests to check if they have been allocated, but there is no delay between loop iterations, so it might just keep checking the same pending request over and over as fast as possible. A metric is also incremented in this flow, so that metric is extremely high, which is probably not the intention.

Changes: Avoid infinite loop by breaking the loop if host affinity is disabled

Tests: new unit test

API changes: N/A

Usage instructions: N/A

Upgrade instructions: None
tree: c7a8b12c7aaf20c396ab59afc45f79cf36acbdd6
  1. bin/
  2. checkstyle/
  3. docs/
  4. gradle/
  5. samza-api/
  6. samza-aws/
  7. samza-azure/
  8. samza-core/
  9. samza-elasticsearch/
  10. samza-hdfs/
  11. samza-kafka/
  12. samza-kv/
  13. samza-kv-couchbase/
  14. samza-kv-inmemory/
  15. samza-kv-rocksdb/
  16. samza-log4j/
  17. samza-log4j2/
  18. samza-rest/
  19. samza-shell/
  20. samza-sql/
  21. samza-sql-shell/
  22. samza-test/
  23. samza-tools/
  24. samza-yarn/
  25. .gitignore
  26. .reviewboardrc
  27. .travis.yml
  28. bootstrap.gradle
  29. build.gradle
  30. doap_Samza.rdf
  31. gradle.properties
  32. gradlew
  33. gradlew.bat
  34. HEADER
  35. KEYS
  36. LICENSE
  37. NOTICE
  38. README.md
  39. RELEASE.md
  40. settings.gradle
  41. sonar-project.properties
README.md

What is Samza? Build Status

Apache Samza is a distributed stream processing framework. It uses Apache Kafka for messaging, and Apache Hadoop YARN to provide fault tolerance, processor isolation, security, and resource management.

Samza's key features include:

  • Simple API: Unlike most low-level messaging system APIs, Samza provides a very simple callback-based “process message” API comparable to MapReduce.
  • Managed state: Samza manages snapshotting and restoration of a stream processor's state. When the processor is restarted, Samza restores its state to a consistent snapshot. Samza is built to handle large amounts of state (many gigabytes per partition).
  • Fault tolerance: Whenever a machine in the cluster fails, Samza works with YARN to transparently migrate your tasks to another machine.
  • Durability: Samza uses Kafka to guarantee that messages are processed in the order they were written to a partition, and that no messages are ever lost.
  • Scalability: Samza is partitioned and distributed at every level. Kafka provides ordered, partitioned, replayable, fault-tolerant streams. YARN provides a distributed environment for Samza containers to run in.
  • Pluggable: Though Samza works out of the box with Kafka and YARN, Samza provides a pluggable API that lets you run Samza with other messaging systems and execution environments.
  • Processor isolation: Samza works with Apache YARN, which supports Hadoop's security model, and resource isolation through Linux CGroups.

Check out Hello Samza to try Samza. Read the Background page to learn more about Samza.

Building Samza

To build Samza from a git checkout, run:

./gradlew clean build

To build Samza from a source release, it is first necessary to download the gradle wrapper script above. This bootstrapping process requires Gradle to be installed on the source machine. Gradle is available through most package managers or directly from its website. To bootstrap the wrapper, run:

gradle -b bootstrap.gradle

After the bootstrap script has completed, the regular gradlew instructions below are available.

Scala and YARN

Samza builds with Scala 2.11 or 2.12 and YARN 2.6.1, by default. Use the -PscalaSuffix switches to change Scala versions. Samza supports building Scala with 2.11 and 2.12.

./gradlew -PscalaSuffix=2.11 clean build

Testing Samza

To run all tests:

./gradlew clean test

To run a single test:

./gradlew clean :samza-test:test -Dtest.single=TestStatefulTask

To run key-value performance tests:

./gradlew samza-shell:kvPerformanceTest -PconfigPath=file://$PWD/samza-test/src/main/config/perf/kv-perf.properties

To run yarn integration tests:

./bin/integration-tests.sh <dir> yarn-integration-tests

To run standalone integration tests:

./bin/integration-tests.sh <dir> standalone-integration-tests

Running checkstyle on the java code

./gradlew checkstyleMain checkstyleTest

Job Management

To run a job (defined in a properties file):

./gradlew samza-shell:runJob -PconfigPath=/path/to/job/config.properties

To inspect a job's latest checkpoint:

./gradlew samza-shell:checkpointTool -PconfigPath=/path/to/job/config.properties

To modify a job's checkpoint (assumes that the job is not currently running), give it a file with the new offset for each partition, in the format systems.<system>.streams.<topic>.partitions.<partition>=<offset>:

./gradlew samza-shell:checkpointTool -PconfigPath=/path/to/job/config.properties \
    -PnewOffsets=file:///path/to/new/offsets.properties

Developers

To get Eclipse projects, run:

./gradlew eclipse

For IntelliJ, run:

./gradlew idea

Contribution

To start contributing on Samza please read Rules and Contributor Corner. Notice that Samza git repository does not support git pull request.

Apache Software Foundation

Apache Samza is a top level project of the Apache Software Foundation.

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