Make sure the following requirements are met and software installed on your machine.
The published Comet jar files in Maven Central bundle native libraries for Linux only (amd64 and arm64). macOS users must build from source.
| Operating System | Published Maven Jars | Build from Source |
|---|---|---|
| Linux (amd64) | Yes | Yes |
| Linux (arm64) | Yes | Yes |
| Apple macOS (Apple Silicon) | No | Yes |
Comet $COMET_VERSION supports the following versions of Apache Spark. Refer to the Spark Version Compatibility page in the Compatibility Guide for more information, such as known limitations per Spark version.
We recommend only using Comet with Spark versions where we currently have both Comet and Spark tests enabled in CI. Other versions may work well enough for development and evaluation purposes.
JDK 11 and Spark 3.4 support are deprecated as of the 1.0.0 release and will be removed in the 1.1.0 release. We recommend moving to JDK 17 or later and Spark 3.5 or later.
| Spark Version | Java Version | Scala Version | Comet Tests in CI | Spark SQL Tests in CI |
|---|---|---|---|---|
| 3.4.3 | 11/17 | 2.12/2.13 | Yes | Yes |
| 3.5.9 | 11/17 | 2.12/2.13 | Yes | Yes |
| 4.0.4 | 17/21 | 2.13 | Yes | Yes |
| 4.1.3 | 17/21 | 2.13 | Yes | Yes |
Note that we do not test the full matrix of supported Java and Scala versions in CI for every Spark version.
Experimental support is provided for the following versions of Apache Spark and is intended for development/testing use only and should not be used in production yet.
| Spark Version | Java Version | Scala Version | Comet Tests in CI | Spark SQL Tests in CI |
|---|---|---|---|---|
| 4.2.0 | 17 | 2.13 | Yes | No |
Note that Comet may not fully work with proprietary forks of Apache Spark such as the Spark versions offered by Cloud Service Providers.
This documentation is for the current development version of Comet. Published jar files are only available for released versions. To use this version of Comet, see Building from source.
Comet jar files are available in Maven Central for amd64 and arm64 architectures for Linux. For Apple macOS, it is currently necessary to build from source.
For performance reasons, published Comet jar files target baseline CPUs available in modern data centers. For example, the amd64 build uses the x86-64-v3 target that adds CPU instructions (e.g., AVX2) common after 2013. Similarly, the arm64 build uses the neoverse-n1 target, which is a common baseline for ARM cores found in AWS (Graviton2+), GCP, and Azure after 2019. If the Comet library fails for SIGILL (illegal instruction), please open an issue on the GitHub repository describing your environment, and [build from source] for your target architecture.
Here are the direct links for downloading the Comet $COMET_VERSION jar file.
Refer to the Building from source guide for instructions from building Comet from source, either from official source releases, or from the latest code in the GitHub repository.
See the Comet Kubernetes Guide guide.
Make sure SPARK_HOME points to the same Spark version as Comet was built for.
export COMET_JAR=spark/target/comet-spark-spark4.1_2.13-$COMET_VERSION.jar $SPARK_HOME/bin/spark-shell \ --jars $COMET_JAR \ --conf spark.driver.extraClassPath=$COMET_JAR \ --conf spark.executor.extraClassPath=$COMET_JAR \ --conf spark.plugins=org.apache.spark.CometPlugin \ --conf spark.shuffle.manager=org.apache.spark.sql.comet.execution.shuffle.CometShuffleManager \ --conf spark.comet.explain.fallback.enabled=true \ --conf spark.memory.offHeap.enabled=true \ --conf spark.memory.offHeap.size=4g
Create a test Parquet source
scala> (0 until 10).toDF("a").write.mode("overwrite").parquet("/tmp/test")
Comet will log output similar to:
INFO core/src/lib.rs: Comet native library version $COMET_VERSION initialized WARN CometExecRule: Comet cannot execute some parts of this plan natively (set spark.comet.explain.fallback.enabled=false to disable this logging): Execute InsertIntoHadoopFsRelationCommand [COMET: Native support for operator DataWritingCommandExec is disabled. Set spark.comet.parquet.write.enabled=true to enable it.] +- WriteFiles +- LocalTableScan [COMET: Native support for operator LocalTableScanExec is disabled. Set spark.comet.exec.localTableScan.enabled=true to enable it.]
Query the data from the test source and check:
scala> spark.read.parquet("/tmp/test").createOrReplaceTempView("t1") scala> spark.sql("select * from t1 where a > 5").explain
Comet will log output similar to:
== Physical Plan == CometColumnarToRow +- CometFilter [a#6], (isnotnull(a#6) AND (a#6 > 5)) +- CometNativeScan parquet [a#6] Batched: true, DataFilters: [isnotnull(a#6), (a#6 > 5)], Format: CometParquet, Location: InMemoryFileIndex(1 paths)[file:/tmp/test], PartitionFilters: [], PushedFilters: [IsNotNull(a), GreaterThan(a,5)], ReadSchema: struct<a:int>
When the Comet plugin is loaded, it exposes its build version as the Spark config spark.comet.version. This can be queried at runtime from any supported language, for example:
scala> spark.conf.get("spark.comet.version")
SET spark.comet.version;
The same value is available programmatically on the JVM classpath, along with additional build metadata that is useful when reporting issues:
scala> import org.apache.comet.{COMET_VERSION, COMET_BRANCH, COMET_REVISION} scala> println(COMET_VERSION)
Comet also logs its version when the native library is initialized:
INFO core/src/lib.rs: Comet native library version <version> initialized
Depending on your deployment mode you may also need to set the driver & executor class path(s) to explicitly contain Comet otherwise Spark may use a different class-loader for the Comet components than its internal components which will then fail at runtime. For example:
--driver-class-path spark/target/comet-spark-spark4.1_2.13-$COMET_VERSION.jar
Some cluster managers may require additional configuration, see https://spark.apache.org/docs/latest/cluster-overview.html
In addition to Apache Spark memory configuration parameters, Comet introduces additional parameters to configure memory allocation for native execution. See Comet Memory Tuning for details.