Spark Configuration

Spark provides three locations to configure the system:

Spark Properties

Spark properties control most application settings and are configured separately for each application. These properties can be set directly on a SparkConf passed to your SparkContext. SparkConf allows you to configure some of the common properties (e.g. master URL and application name), as well as arbitrary key-value pairs through the set() method. For example, we could initialize an application with two threads as follows:

Note that we run with local[2], meaning two threads - which represents “minimal” parallelism, which can help detect bugs that only exist when we run in a distributed context.

val conf = new SparkConf()
             .setMaster("local[2]")
             .setAppName("CountingSheep")
val sc = new SparkContext(conf)

Note that we can have more than 1 thread in local mode, and in cases like Spark Streaming, we may actually require more than 1 thread to prevent any sort of starvation issues.

Properties that specify some time duration should be configured with a unit of time. The following format is accepted:

25ms (milliseconds)
5s (seconds)
10m or 10min (minutes)
3h (hours)
5d (days)
1y (years)

Properties that specify a byte size should be configured with a unit of size.
The following format is accepted:

1b (bytes)
1k or 1kb (kibibytes = 1024 bytes)
1m or 1mb (mebibytes = 1024 kibibytes)
1g or 1gb (gibibytes = 1024 mebibytes)
1t or 1tb (tebibytes = 1024 gibibytes)
1p or 1pb (pebibytes = 1024 tebibytes)

Dynamically Loading Spark Properties

In some cases, you may want to avoid hard-coding certain configurations in a SparkConf. For instance, if you’d like to run the same application with different masters or different amounts of memory. Spark allows you to simply create an empty conf:

val sc = new SparkContext(new SparkConf())

Then, you can supply configuration values at runtime:

./bin/spark-submit --name "My app" --master local[4] --conf spark.eventLog.enabled=false
  --conf "spark.executor.extraJavaOptions=-XX:+PrintGCDetails -XX:+PrintGCTimeStamps" myApp.jar

The Spark shell and spark-submit tool support two ways to load configurations dynamically. The first are command line options, such as --master, as shown above. spark-submit can accept any Spark property using the --conf flag, but uses special flags for properties that play a part in launching the Spark application. Running ./bin/spark-submit --help will show the entire list of these options.

bin/spark-submit will also read configuration options from conf/spark-defaults.conf, in which each line consists of a key and a value separated by whitespace. For example:

spark.master            spark://5.6.7.8:7077
spark.executor.memory   4g
spark.eventLog.enabled  true
spark.serializer        org.apache.spark.serializer.KryoSerializer

Any values specified as flags or in the properties file will be passed on to the application and merged with those specified through SparkConf. Properties set directly on the SparkConf take highest precedence, then flags passed to spark-submit or spark-shell, then options in the spark-defaults.conf file. A few configuration keys have been renamed since earlier versions of Spark; in such cases, the older key names are still accepted, but take lower precedence than any instance of the newer key.

Viewing Spark Properties

The application web UI at http://<driver>:4040 lists Spark properties in the “Environment” tab. This is a useful place to check to make sure that your properties have been set correctly. Note that only values explicitly specified through spark-defaults.conf, SparkConf, or the command line will appear. For all other configuration properties, you can assume the default value is used.

Available Properties

Most of the properties that control internal settings have reasonable default values. Some of the most common options to set are:

Application Properties

Property NameDefaultMeaning
spark.app.name (none) The name of your application. This will appear in the UI and in log data.
spark.driver.cores 1 Number of cores to use for the driver process, only in cluster mode.
spark.driver.maxResultSize 1g Limit of total size of serialized results of all partitions for each Spark action (e.g. collect). Should be at least 1M, or 0 for unlimited. Jobs will be aborted if the total size is above this limit. Having a high limit may cause out-of-memory errors in driver (depends on spark.driver.memory and memory overhead of objects in JVM). Setting a proper limit can protect the driver from out-of-memory errors.
spark.driver.memory 1g Amount of memory to use for the driver process, i.e. where SparkContext is initialized. (e.g. 1g, 2g).
Note: In client mode, this config must not be set through the SparkConf directly in your application, because the driver JVM has already started at that point. Instead, please set this through the --driver-memory command line option or in your default properties file.
spark.executor.memory 1g Amount of memory to use per executor process (e.g. 2g, 8g).
spark.extraListeners (none) A comma-separated list of classes that implement SparkListener; when initializing SparkContext, instances of these classes will be created and registered with Spark's listener bus. If a class has a single-argument constructor that accepts a SparkConf, that constructor will be called; otherwise, a zero-argument constructor will be called. If no valid constructor can be found, the SparkContext creation will fail with an exception.
spark.local.dir /tmp Directory to use for "scratch" space in Spark, including map output files and RDDs that get stored on disk. This should be on a fast, local disk in your system. It can also be a comma-separated list of multiple directories on different disks. NOTE: In Spark 1.0 and later this will be overriden by SPARK_LOCAL_DIRS (Standalone, Mesos) or LOCAL_DIRS (YARN) environment variables set by the cluster manager.
spark.logConf false Logs the effective SparkConf as INFO when a SparkContext is started.
spark.master (none) The cluster manager to connect to. See the list of allowed master URL's.

Apart from these, the following properties are also available, and may be useful in some situations:

Runtime Environment

Property NameDefaultMeaning
spark.driver.extraClassPath (none) Extra classpath entries to prepend to the classpath of the driver.
Note: In client mode, this config must not be set through the SparkConf directly in your application, because the driver JVM has already started at that point. Instead, please set this through the --driver-class-path command line option or in your default properties file.
spark.driver.extraJavaOptions (none) A string of extra JVM options to pass to the driver. For instance, GC settings or other logging.
Note: In client mode, this config must not be set through the SparkConf directly in your application, because the driver JVM has already started at that point. Instead, please set this through the --driver-java-options command line option or in your default properties file.
spark.driver.extraLibraryPath (none) Set a special library path to use when launching the driver JVM.
Note: In client mode, this config must not be set through the SparkConf directly in your application, because the driver JVM has already started at that point. Instead, please set this through the --driver-library-path command line option or in your default properties file.
spark.driver.userClassPathFirst false (Experimental) Whether to give user-added jars precedence over Spark's own jars when loading classes in the the driver. This feature can be used to mitigate conflicts between Spark's dependencies and user dependencies. It is currently an experimental feature. This is used in cluster mode only.
spark.executor.extraClassPath (none) Extra classpath entries to prepend to the classpath of executors. This exists primarily for backwards-compatibility with older versions of Spark. Users typically should not need to set this option.
spark.executor.extraJavaOptions (none) A string of extra JVM options to pass to executors. For instance, GC settings or other logging. Note that it is illegal to set Spark properties or heap size settings with this option. Spark properties should be set using a SparkConf object or the spark-defaults.conf file used with the spark-submit script. Heap size settings can be set with spark.executor.memory.
spark.executor.extraLibraryPath (none) Set a special library path to use when launching executor JVM's.
spark.executor.logs.rolling.maxRetainedFiles (none) Sets the number of latest rolling log files that are going to be retained by the system. Older log files will be deleted. Disabled by default.
spark.executor.logs.rolling.maxSize (none) Set the max size of the file by which the executor logs will be rolled over. Rolling is disabled by default. See spark.executor.logs.rolling.maxRetainedFiles for automatic cleaning of old logs.
spark.executor.logs.rolling.strategy (none) Set the strategy of rolling of executor logs. By default it is disabled. It can be set to "time" (time-based rolling) or "size" (size-based rolling). For "time", use spark.executor.logs.rolling.time.interval to set the rolling interval. For "size", use spark.executor.logs.rolling.size.maxBytes to set the maximum file size for rolling.
spark.executor.logs.rolling.time.interval daily Set the time interval by which the executor logs will be rolled over. Rolling is disabled by default. Valid values are daily, hourly, minutely or any interval in seconds. See spark.executor.logs.rolling.maxRetainedFiles for automatic cleaning of old logs.
spark.executor.userClassPathFirst false (Experimental) Same functionality as spark.driver.userClassPathFirst, but applied to executor instances.
spark.executorEnv.[EnvironmentVariableName] (none) Add the environment variable specified by EnvironmentVariableName to the Executor process. The user can specify multiple of these to set multiple environment variables.
spark.python.profile false Enable profiling in Python worker, the profile result will show up by sc.show_profiles(), or it will be displayed before the driver exiting. It also can be dumped into disk by sc.dump_profiles(path). If some of the profile results had been displayed manually, they will not be displayed automatically before driver exiting. By default the pyspark.profiler.BasicProfiler will be used, but this can be overridden by passing a profiler class in as a parameter to the SparkContext constructor.
spark.python.profile.dump (none) The directory which is used to dump the profile result before driver exiting. The results will be dumped as separated file for each RDD. They can be loaded by ptats.Stats(). If this is specified, the profile result will not be displayed automatically.
spark.python.worker.memory 512m Amount of memory to use per python worker process during aggregation, in the same format as JVM memory strings (e.g. 512m, 2g). If the memory used during aggregation goes above this amount, it will spill the data into disks.
spark.python.worker.reuse true Reuse Python worker or not. If yes, it will use a fixed number of Python workers, does not need to fork() a Python process for every tasks. It will be very useful if there is large broadcast, then the broadcast will not be needed to transfered from JVM to Python worker for every task.

Shuffle Behavior

Property NameDefaultMeaning
spark.reducer.maxSizeInFlight 48m Maximum size of map outputs to fetch simultaneously from each reduce task. Since each output requires us to create a buffer to receive it, this represents a fixed memory overhead per reduce task, so keep it small unless you have a large amount of memory.
spark.shuffle.compress true Whether to compress map output files. Generally a good idea. Compression will use spark.io.compression.codec.
spark.shuffle.file.buffer 32k Size of the in-memory buffer for each shuffle file output stream. These buffers reduce the number of disk seeks and system calls made in creating intermediate shuffle files.
spark.shuffle.io.maxRetries 3 (Netty only) Fetches that fail due to IO-related exceptions are automatically retried if this is set to a non-zero value. This retry logic helps stabilize large shuffles in the face of long GC pauses or transient network connectivity issues.
spark.shuffle.io.numConnectionsPerPeer 1 (Netty only) Connections between hosts are reused in order to reduce connection buildup for large clusters. For clusters with many hard disks and few hosts, this may result in insufficient concurrency to saturate all disks, and so users may consider increasing this value.
spark.shuffle.io.preferDirectBufs true (Netty only) Off-heap buffers are used to reduce garbage collection during shuffle and cache block transfer. For environments where off-heap memory is tightly limited, users may wish to turn this off to force all allocations from Netty to be on-heap.
spark.shuffle.io.retryWait 5s (Netty only) How long to wait between retries of fetches. The maximum delay caused by retrying is 15 seconds by default, calculated as maxRetries * retryWait.
spark.shuffle.manager sort Implementation to use for shuffling data. There are two implementations available: sort and hash. Sort-based shuffle is more memory-efficient and is the default option starting in 1.2.
spark.shuffle.service.enabled false Enables the external shuffle service. This service preserves the shuffle files written by executors so the executors can be safely removed. This must be enabled if spark.dynamicAllocation.enabled is "true". The external shuffle service must be set up in order to enable it. See dynamic allocation configuration and setup documentation for more information.
spark.shuffle.service.port 7337 Port on which the external shuffle service will run.
spark.shuffle.sort.bypassMergeThreshold 200 (Advanced) In the sort-based shuffle manager, avoid merge-sorting data if there is no map-side aggregation and there are at most this many reduce partitions.
spark.shuffle.spill.compress true Whether to compress data spilled during shuffles. Compression will use spark.io.compression.codec.

Spark UI

Property NameDefaultMeaning
spark.eventLog.compress false Whether to compress logged events, if spark.eventLog.enabled is true.
spark.eventLog.dir file:///tmp/spark-events Base directory in which Spark events are logged, if spark.eventLog.enabled is true. Within this base directory, Spark creates a sub-directory for each application, and logs the events specific to the application in this directory. Users may want to set this to a unified location like an HDFS directory so history files can be read by the history server.
spark.eventLog.enabled false Whether to log Spark events, useful for reconstructing the Web UI after the application has finished.
spark.ui.killEnabled true Allows stages and corresponding jobs to be killed from the web ui.
spark.ui.port 4040 Port for your application's dashboard, which shows memory and workload data.
spark.ui.retainedJobs 1000 How many jobs the Spark UI and status APIs remember before garbage collecting.
spark.ui.retainedStages 1000 How many stages the Spark UI and status APIs remember before garbage collecting.
spark.worker.ui.retainedExecutors 1000 How many finished executors the Spark UI and status APIs remember before garbage collecting.
spark.worker.ui.retainedDrivers 1000 How many finished drivers the Spark UI and status APIs remember before garbage collecting.
spark.sql.ui.retainedExecutions 1000 How many finished executions the Spark UI and status APIs remember before garbage collecting.
spark.streaming.ui.retainedBatches 1000 How many finished batches the Spark UI and status APIs remember before garbage collecting.

Compression and Serialization

Property NameDefaultMeaning
spark.broadcast.compress true Whether to compress broadcast variables before sending them. Generally a good idea.
spark.closure.serializer org.apache.spark.serializer.
JavaSerializer		 Serializer class to use for closures. Currently only the Java serializer is supported.
spark.io.compression.codec snappy The codec used to compress internal data such as RDD partitions, broadcast variables and shuffle outputs. By default, Spark provides three codecs: lz4, lzf, and snappy. You can also use fully qualified class names to specify the codec, e.g. org.apache.spark.io.LZ4CompressionCodec, org.apache.spark.io.LZFCompressionCodec, and org.apache.spark.io.SnappyCompressionCodec.
spark.io.compression.lz4.blockSize 32k Block size used in LZ4 compression, in the case when LZ4 compression codec is used. Lowering this block size will also lower shuffle memory usage when LZ4 is used.
spark.io.compression.snappy.blockSize 32k Block size used in Snappy compression, in the case when Snappy compression codec is used. Lowering this block size will also lower shuffle memory usage when Snappy is used.
spark.kryo.classesToRegister (none) If you use Kryo serialization, give a comma-separated list of custom class names to register with Kryo. See the tuning guide for more details.
spark.kryo.referenceTracking true (false when using Spark SQL Thrift Server) Whether to track references to the same object when serializing data with Kryo, which is necessary if your object graphs have loops and useful for efficiency if they contain multiple copies of the same object. Can be disabled to improve performance if you know this is not the case.
spark.kryo.registrationRequired false Whether to require registration with Kryo. If set to 'true', Kryo will throw an exception if an unregistered class is serialized. If set to false (the default), Kryo will write unregistered class names along with each object. Writing class names can cause significant performance overhead, so enabling this option can enforce strictly that a user has not omitted classes from registration.
spark.kryo.registrator (none) If you use Kryo serialization, set this class to register your custom classes with Kryo. This property is useful if you need to register your classes in a custom way, e.g. to specify a custom field serializer. Otherwise spark.kryo.classesToRegister is simpler. It should be set to a class that extends KryoRegistrator. See the tuning guide for more details.
spark.kryoserializer.buffer.max 64m Maximum allowable size of Kryo serialization buffer. This must be larger than any object you attempt to serialize. Increase this if you get a "buffer limit exceeded" exception inside Kryo.
spark.kryoserializer.buffer 64k Initial size of Kryo's serialization buffer. Note that there will be one buffer per core on each worker. This buffer will grow up to spark.kryoserializer.buffer.max if needed.
spark.rdd.compress false Whether to compress serialized RDD partitions (e.g. for StorageLevel.MEMORY_ONLY_SER). Can save substantial space at the cost of some extra CPU time.
spark.serializer org.apache.spark.serializer.
JavaSerializer (org.apache.spark.serializer.
KryoSerializer when using Spark SQL Thrift Server) 		Class to use for serializing objects that will be sent over the network or need to be cached in serialized form. The default of Java serialization works with any Serializable Java object but is quite slow, so we recommend using org.apache.spark.serializer.KryoSerializer and configuring Kryo serialization when speed is necessary. Can be any subclass of org.apache.spark.Serializer.
spark.serializer.objectStreamReset 100 When serializing using org.apache.spark.serializer.JavaSerializer, the serializer caches objects to prevent writing redundant data, however that stops garbage collection of those objects. By calling 'reset' you flush that info from the serializer, and allow old objects to be collected. To turn off this periodic reset set it to -1. By default it will reset the serializer every 100 objects.

Memory Management

Property NameDefaultMeaning
spark.memory.fraction 0.75 Fraction of (heap space - 300MB) used for execution and storage. The lower this is, the more frequently spills and cached data eviction occur. The purpose of this config is to set aside memory for internal metadata, user data structures, and imprecise size estimation in the case of sparse, unusually large records. Leaving this at the default value is recommended. For more detail, see this description.
spark.memory.storageFraction 0.5 Amount of storage memory immune to eviction, expressed as a fraction of the size of the region set aside by s​park.memory.fraction. The higher this is, the less working memory may be available to execution and tasks may spill to disk more often. Leaving this at the default value is recommended. For more detail, see this description.
spark.memory.offHeap.enabled true If true, Spark will attempt to use off-heap memory for certain operations. If off-heap memory use is enabled, then spark.memory.offHeap.size must be positive.
spark.memory.offHeap.size 0 The absolute amount of memory which can be used for off-heap allocation. This setting has no impact on heap memory usage, so if your executors' total memory consumption must fit within some hard limit then be sure to shrink your JVM heap size accordingly. This must be set to a positive value when spark.memory.offHeap.enabled=true.
spark.memory.useLegacyMode false ​Whether to enable the legacy memory management mode used in Spark 1.5 and before. The legacy mode rigidly partitions the heap space into fixed-size regions, potentially leading to excessive spilling if the application was not tuned. The following deprecated memory fraction configurations are not read unless this is enabled: spark.shuffle.memoryFraction
spark.storage.memoryFraction
spark.storage.unrollFraction
spark.shuffle.memoryFraction 0.2 (deprecated) This is read only if spark.memory.useLegacyMode is enabled. Fraction of Java heap to use for aggregation and cogroups during shuffles. At any given time, the collective size of all in-memory maps used for shuffles is bounded by this limit, beyond which the contents will begin to spill to disk. If spills are often, consider increasing this value at the expense of spark.storage.memoryFraction.
spark.storage.memoryFraction 0.6 (deprecated) This is read only if spark.memory.useLegacyMode is enabled. Fraction of Java heap to use for Spark's memory cache. This should not be larger than the "old" generation of objects in the JVM, which by default is given 0.6 of the heap, but you can increase it if you configure your own old generation size.
spark.storage.unrollFraction 0.2 (deprecated) This is read only if spark.memory.useLegacyMode is enabled. Fraction of spark.storage.memoryFraction to use for unrolling blocks in memory. This is dynamically allocated by dropping existing blocks when there is not enough free storage space to unroll the new block in its entirety.

Execution Behavior

Property NameDefaultMeaning
spark.broadcast.blockSize 4m Size of each piece of a block for TorrentBroadcastFactory. Too large a value decreases parallelism during broadcast (makes it slower); however, if it is too small, BlockManager might take a performance hit.
spark.broadcast.factory org.apache.spark.broadcast.
TorrentBroadcastFactory		 Which broadcast implementation to use.
spark.cleaner.ttl (infinite) Duration (seconds) of how long Spark will remember any metadata (stages generated, tasks generated, etc.). Periodic cleanups will ensure that metadata older than this duration will be forgotten. This is useful for running Spark for many hours / days (for example, running 24/7 in case of Spark Streaming applications). Note that any RDD that persists in memory for more than this duration will be cleared as well.
spark.executor.cores 1 in YARN mode, all the available cores on the worker in standalone mode. The number of cores to use on each executor. For YARN and standalone mode only. In standalone mode, setting this parameter allows an application to run multiple executors on the same worker, provided that there are enough cores on that worker. Otherwise, only one executor per application will run on each worker.
spark.default.parallelism For distributed shuffle operations like reduceByKey and join, the largest number of partitions in a parent RDD. For operations like parallelize with no parent RDDs, it depends on the cluster manager:
  • Local mode: number of cores on the local machine
  • Mesos fine grained mode: 8
  • Others: total number of cores on all executor nodes or 2, whichever is larger
 Default number of partitions in RDDs returned by transformations like join, reduceByKey, and parallelize when not set by user.
spark.executor.heartbeatInterval 10s Interval between each executor's heartbeats to the driver. Heartbeats let the driver know that the executor is still alive and update it with metrics for in-progress tasks.
spark.files.fetchTimeout 60s Communication timeout to use when fetching files added through SparkContext.addFile() from the driver.
spark.files.useFetchCache true If set to true (default), file fetching will use a local cache that is shared by executors that belong to the same application, which can improve task launching performance when running many executors on the same host. If set to false, these caching optimizations will be disabled and all executors will fetch their own copies of files. This optimization may be disabled in order to use Spark local directories that reside on NFS filesystems (see SPARK-6313 for more details).
spark.files.overwrite false Whether to overwrite files added through SparkContext.addFile() when the target file exists and its contents do not match those of the source.
spark.hadoop.cloneConf false If set to true, clones a new Hadoop Configuration object for each task. This option should be enabled to work around Configuration thread-safety issues (see SPARK-2546 for more details). This is disabled by default in order to avoid unexpected performance regressions for jobs that are not affected by these issues.
spark.hadoop.validateOutputSpecs true If set to true, validates the output specification (e.g. checking if the output directory already exists) used in saveAsHadoopFile and other variants. This can be disabled to silence exceptions due to pre-existing output directories. We recommend that users do not disable this except if trying to achieve compatibility with previous versions of Spark. Simply use Hadoop's FileSystem API to delete output directories by hand. This setting is ignored for jobs generated through Spark Streaming's StreamingContext, since data may need to be rewritten to pre-existing output directories during checkpoint recovery.
spark.storage.memoryMapThreshold 2m Size of a block above which Spark memory maps when reading a block from disk. This prevents Spark from memory mapping very small blocks. In general, memory mapping has high overhead for blocks close to or below the page size of the operating system.
spark.externalBlockStore.blockManager org.apache.spark.storage.TachyonBlockManager Implementation of external block manager (file system) that store RDDs. The file system's URL is set by spark.externalBlockStore.url.
spark.externalBlockStore.baseDir System.getProperty("java.io.tmpdir") Directories of the external block store that store RDDs. The file system's URL is set by spark.externalBlockStore.url It can also be a comma-separated list of multiple directories on Tachyon file system.
spark.externalBlockStore.url tachyon://localhost:19998 for Tachyon The URL of the underlying external blocker file system in the external block store.

Networking

Property NameDefaultMeaning
spark.akka.frameSize 128 Maximum message size (in MB) to allow in "control plane" communication; generally only applies to map output size information sent between executors and the driver. Increase this if you are running jobs with many thousands of map and reduce tasks and see messages about the frame size.
spark.akka.heartbeat.interval 1000s This is set to a larger value to disable the transport failure detector that comes built in to Akka. It can be enabled again, if you plan to use this feature (Not recommended). A larger interval value reduces network overhead and a smaller value ( ~ 1 s) might be more informative for Akka's failure detector. Tune this in combination of spark.akka.heartbeat.pauses if you need to. A likely positive use case for using failure detector would be: a sensistive failure detector can help evict rogue executors quickly. However this is usually not the case as GC pauses and network lags are expected in a real Spark cluster. Apart from that enabling this leads to a lot of exchanges of heart beats between nodes leading to flooding the network with those.
spark.akka.heartbeat.pauses 6000s This is set to a larger value to disable the transport failure detector that comes built in to Akka. It can be enabled again, if you plan to use this feature (Not recommended). Acceptable heart beat pause for Akka. This can be used to control sensitivity to GC pauses. Tune this along with spark.akka.heartbeat.interval if you need to.
spark.akka.threads 4 Number of actor threads to use for communication. Can be useful to increase on large clusters when the driver has a lot of CPU cores.
spark.akka.timeout 100s Communication timeout between Spark nodes.
spark.blockManager.port (random) Port for all block managers to listen on. These exist on both the driver and the executors.
spark.broadcast.port (random) Port for the driver's HTTP broadcast server to listen on. This is not relevant for torrent broadcast.
spark.driver.host (local hostname) Hostname or IP address for the driver to listen on. This is used for communicating with the executors and the standalone Master.
spark.driver.port (random) Port for the driver to listen on. This is used for communicating with the executors and the standalone Master.
spark.executor.port (random) Port for the executor to listen on. This is used for communicating with the driver.
spark.fileserver.port (random) Port for the driver's HTTP file server to listen on.
spark.network.timeout 120s Default timeout for all network interactions. This config will be used in place of spark.core.connection.ack.wait.timeout, spark.akka.timeout, spark.storage.blockManagerSlaveTimeoutMs, spark.shuffle.io.connectionTimeout, spark.rpc.askTimeout or spark.rpc.lookupTimeout if they are not configured.
spark.port.maxRetries 16 Maximum number of retries when binding to a port before giving up. When a port is given a specific value (non 0), each subsequent retry will increment the port used in the previous attempt by 1 before retrying. This essentially allows it to try a range of ports from the start port specified to port + maxRetries.
spark.replClassServer.port (random) Port for the driver's HTTP class server to listen on. This is only relevant for the Spark shell.
spark.rpc.numRetries 3 Number of times to retry before an RPC task gives up. An RPC task will run at most times of this number.
spark.rpc.retry.wait 3s Duration for an RPC ask operation to wait before retrying.
spark.rpc.askTimeout 120s Duration for an RPC ask operation to wait before timing out.
spark.rpc.lookupTimeout 120s Duration for an RPC remote endpoint lookup operation to wait before timing out.

Scheduling

Property NameDefaultMeaning
spark.cores.max (not set) When running on a standalone deploy cluster or a Mesos cluster in "coarse-grained" sharing mode, the maximum amount of CPU cores to request for the application from across the cluster (not from each machine). If not set, the default will be spark.deploy.defaultCores on Spark's standalone cluster manager, or infinite (all available cores) on Mesos.
spark.locality.wait 3s How long to wait to launch a data-local task before giving up and launching it on a less-local node. The same wait will be used to step through multiple locality levels (process-local, node-local, rack-local and then any). It is also possible to customize the waiting time for each level by setting spark.locality.wait.node, etc. You should increase this setting if your tasks are long and see poor locality, but the default usually works well.
spark.locality.wait.node spark.locality.wait Customize the locality wait for node locality. For example, you can set this to 0 to skip node locality and search immediately for rack locality (if your cluster has rack information).
spark.locality.wait.process spark.locality.wait Customize the locality wait for process locality. This affects tasks that attempt to access cached data in a particular executor process.
spark.locality.wait.rack spark.locality.wait Customize the locality wait for rack locality.
spark.scheduler.maxRegisteredResourcesWaitingTime 30s Maximum amount of time to wait for resources to register before scheduling begins.
spark.scheduler.minRegisteredResourcesRatio 0.8 for YARN mode; 0.0 for standalone mode and Mesos coarse-grained mode The minimum ratio of registered resources (registered resources / total expected resources) (resources are executors in yarn mode, CPU cores in standalone mode and Mesos coarsed-grained mode ['spark.cores.max' value is total expected resources for Mesos coarse-grained mode] ) to wait for before scheduling begins. Specified as a double between 0.0 and 1.0. Regardless of whether the minimum ratio of resources has been reached, the maximum amount of time it will wait before scheduling begins is controlled by config spark.scheduler.maxRegisteredResourcesWaitingTime.
spark.scheduler.mode FIFO The scheduling mode between jobs submitted to the same SparkContext. Can be set to FAIR to use fair sharing instead of queueing jobs one after another. Useful for multi-user services.
spark.scheduler.revive.interval 1s The interval length for the scheduler to revive the worker resource offers to run tasks.
spark.speculation false If set to "true", performs speculative execution of tasks. This means if one or more tasks are running slowly in a stage, they will be re-launched.
spark.speculation.interval 100ms How often Spark will check for tasks to speculate.
spark.speculation.multiplier 1.5 How many times slower a task is than the median to be considered for speculation.
spark.speculation.quantile 0.75 Percentage of tasks which must be complete before speculation is enabled for a particular stage.
spark.task.cpus 1 Number of cores to allocate for each task.
spark.task.maxFailures 4 Number of individual task failures before giving up on the job. Should be greater than or equal to 1. Number of allowed retries = this value - 1.

Dynamic Allocation

Property NameDefaultMeaning
spark.dynamicAllocation.enabled false Whether to use dynamic resource allocation, which scales the number of executors registered with this application up and down based on the workload. Note that this is currently only available on YARN mode. For more detail, see the description here.

This requires spark.shuffle.service.enabled to be set. The following configurations are also relevant: spark.dynamicAllocation.minExecutors, spark.dynamicAllocation.maxExecutors, and spark.dynamicAllocation.initialExecutors
spark.dynamicAllocation.executorIdleTimeout 60s If dynamic allocation is enabled and an executor has been idle for more than this duration, the executor will be removed. For more detail, see this description.
spark.dynamicAllocation.cachedExecutorIdleTimeout infinity If dynamic allocation is enabled and an executor which has cached data blocks has been idle for more than this duration, the executor will be removed. For more details, see this description.
spark.dynamicAllocation.initialExecutors spark.dynamicAllocation.minExecutors Initial number of executors to run if dynamic allocation is enabled.
spark.dynamicAllocation.maxExecutors infinity Upper bound for the number of executors if dynamic allocation is enabled.
spark.dynamicAllocation.minExecutors 0 Lower bound for the number of executors if dynamic allocation is enabled.
spark.dynamicAllocation.schedulerBacklogTimeout 1s If dynamic allocation is enabled and there have been pending tasks backlogged for more than this duration, new executors will be requested. For more detail, see this description.
spark.dynamicAllocation.sustainedSchedulerBacklogTimeout schedulerBacklogTimeout Same as spark.dynamicAllocation.schedulerBacklogTimeout, but used only for subsequent executor requests. For more detail, see this description.

Security

Property NameDefaultMeaning
spark.acls.enable false Whether Spark acls should are enabled. If enabled, this checks to see if the user has access permissions to view or modify the job. Note this requires the user to be known, so if the user comes across as null no checks are done. Filters can be used with the UI to authenticate and set the user.
spark.admin.acls Empty Comma separated list of users/administrators that have view and modify access to all Spark jobs. This can be used if you run on a shared cluster and have a set of administrators or devs who help debug when things work. Putting a "*" in the list means any user can have the priviledge of admin.
spark.authenticate false Whether Spark authenticates its internal connections. See spark.authenticate.secret if not running on YARN.
spark.authenticate.secret None Set the secret key used for Spark to authenticate between components. This needs to be set if not running on YARN and authentication is enabled.
spark.authenticate.enableSaslEncryption false Enable encrypted communication when authentication is enabled. This option is currently only supported by the block transfer service.
spark.network.sasl.serverAlwaysEncrypt false Disable unencrypted connections for services that support SASL authentication. This is currently supported by the external shuffle service.
spark.core.connection.ack.wait.timeout 60s How long for the connection to wait for ack to occur before timing out and giving up. To avoid unwilling timeout caused by long pause like GC, you can set larger value.
spark.core.connection.auth.wait.timeout 30s How long for the connection to wait for authentication to occur before timing out and giving up.
spark.modify.acls Empty Comma separated list of users that have modify access to the Spark job. By default only the user that started the Spark job has access to modify it (kill it for example). Putting a "*" in the list means any user can have access to modify it.
spark.ui.filters None Comma separated list of filter class names to apply to the Spark web UI. The filter should be a standard javax servlet Filter. Parameters to each filter can also be specified by setting a java system property of:
spark.<class name of filter>.params='param1=value1,param2=value2'
For example:
-Dspark.ui.filters=com.test.filter1
-Dspark.com.test.filter1.params='param1=foo,param2=testing'
spark.ui.view.acls Empty Comma separated list of users that have view access to the Spark web ui. By default only the user that started the Spark job has view access. Putting a "*" in the list means any user can have view access to this Spark job.

Encryption

Property NameDefaultMeaning
spark.ssl.enabled false

Whether to enable SSL connections on all supported protocols.

All the SSL settings like spark.ssl.xxx where xxx is a particular configuration property, denote the global configuration for all the supported protocols. In order to override the global configuration for the particular protocol, the properties must be overwritten in the protocol-specific namespace.

Use spark.ssl.YYY.XXX settings to overwrite the global configuration for particular protocol denoted by YYY. Currently YYY can be either akka for Akka based connections or fs for broadcast and file server.
spark.ssl.enabledAlgorithms Empty A comma separated list of ciphers. The specified ciphers must be supported by JVM. The reference list of protocols one can find on this page.
spark.ssl.keyPassword None A password to the private key in key-store.
spark.ssl.keyStore None A path to a key-store file. The path can be absolute or relative to the directory where the component is started in.
spark.ssl.keyStorePassword None A password to the key-store.
spark.ssl.protocol None A protocol name. The protocol must be supported by JVM. The reference list of protocols one can find on this page.
spark.ssl.trustStore None A path to a trust-store file. The path can be absolute or relative to the directory where the component is started in.
spark.ssl.trustStorePassword None A password to the trust-store.

Spark Streaming

Property NameDefaultMeaning
spark.streaming.backpressure.enabled false Enables or disables Spark Streaming's internal backpressure mechanism (since 1.5). This enables the Spark Streaming to control the receiving rate based on the current batch scheduling delays and processing times so that the system receives only as fast as the system can process. Internally, this dynamically sets the maximum receiving rate of receivers. This rate is upper bounded by the values spark.streaming.receiver.maxRate and spark.streaming.kafka.maxRatePerPartition if they are set (see below).
spark.streaming.blockInterval 200ms Interval at which data received by Spark Streaming receivers is chunked into blocks of data before storing them in Spark. Minimum recommended - 50 ms. See the performance tuning section in the Spark Streaming programing guide for more details.
spark.streaming.receiver.maxRate not set Maximum rate (number of records per second) at which each receiver will receive data. Effectively, each stream will consume at most this number of records per second. Setting this configuration to 0 or a negative number will put no limit on the rate. See the deployment guide in the Spark Streaming programing guide for mode details.
spark.streaming.receiver.writeAheadLog.enable false Enable write ahead logs for receivers. All the input data received through receivers will be saved to write ahead logs that will allow it to be recovered after driver failures. See the deployment guide in the Spark Streaming programing guide for more details.
spark.streaming.unpersist true Force RDDs generated and persisted by Spark Streaming to be automatically unpersisted from Spark's memory. The raw input data received by Spark Streaming is also automatically cleared. Setting this to false will allow the raw data and persisted RDDs to be accessible outside the streaming application as they will not be cleared automatically. But it comes at the cost of higher memory usage in Spark.
spark.streaming.stopGracefullyOnShutdown false If true, Spark shuts down the StreamingContext gracefully on JVM shutdown rather than immediately.
spark.streaming.kafka.maxRatePerPartition not set Maximum rate (number of records per second) at which data will be read from each Kafka partition when using the new Kafka direct stream API. See the Kafka Integration guide for more details.
spark.streaming.kafka.maxRetries 1 Maximum number of consecutive retries the driver will make in order to find the latest offsets on the leader of each partition (a default value of 1 means that the driver will make a maximum of 2 attempts). Only applies to the new Kafka direct stream API.
spark.streaming.ui.retainedBatches 1000 How many batches the Spark Streaming UI and status APIs remember before garbage collecting.

SparkR

Property NameDefaultMeaning
spark.r.numRBackendThreads 2 Number of threads used by RBackend to handle RPC calls from SparkR package.
spark.r.command Rscript Executable for executing R scripts in cluster modes for both driver and workers.
spark.r.driver.command spark.r.command Executable for executing R scripts in client modes for driver. Ignored in cluster modes.

Cluster Managers

Each cluster manager in Spark has additional configuration options. Configurations can be found on the pages for each mode:

YARN
Mesos
Standalone Mode

Environment Variables

Certain Spark settings can be configured through environment variables, which are read from the conf/spark-env.sh script in the directory where Spark is installed (or conf/spark-env.cmd on Windows). In Standalone and Mesos modes, this file can give machine specific information such as hostnames. It is also sourced when running local Spark applications or submission scripts.

Note that conf/spark-env.sh does not exist by default when Spark is installed. However, you can copy conf/spark-env.sh.template to create it. Make sure you make the copy executable.

The following variables can be set in spark-env.sh:

Environment VariableMeaning
JAVA_HOME Location where Java is installed (if it's not on your default PATH).
PYSPARK_PYTHON Python binary executable to use for PySpark in both driver and workers (default is python).
PYSPARK_DRIVER_PYTHON Python binary executable to use for PySpark in driver only (default is PYSPARK_PYTHON).
SPARKR_DRIVER_R R binary executable to use for SparkR shell (default is R).
SPARK_LOCAL_IP IP address of the machine to bind to.
SPARK_PUBLIC_DNS Hostname your Spark program will advertise to other machines.

In addition to the above, there are also options for setting up the Spark standalone cluster scripts, such as number of cores to use on each machine and maximum memory.

Since spark-env.sh is a shell script, some of these can be set programmatically – for example, you might compute SPARK_LOCAL_IP by looking up the IP of a specific network interface.

Configuring Logging

Spark uses log4j for logging. You can configure it by adding a log4j.properties file in the conf directory. One way to start is to copy the existing log4j.properties.template located there.

Overriding configuration directory

To specify a different configuration directory other than the default “SPARK_HOME/conf”, you can set SPARK_CONF_DIR. Spark will use the the configuration files (spark-defaults.conf, spark-env.sh, log4j.properties, etc) from this directory.

Inheriting Hadoop Cluster Configuration

If you plan to read and write from HDFS using Spark, there are two Hadoop configuration files that should be included on Spark’s classpath:

The location of these configuration files varies across CDH and HDP versions, but a common location is inside of /etc/hadoop/conf. Some tools, such as Cloudera Manager, create configurations on-the-fly, but offer a mechanisms to download copies of them.

To make these files visible to Spark, set HADOOP_CONF_DIR in $SPARK_HOME/spark-env.sh to a location containing the configuration files.