spark executor memory layout


Understand Google api.ai and build Artificial Intelligent Assistant, Understanding Resource Allocation configurations for a Spark application, Kafka A great choice for large scale event processing, Installing Apache Zeppelin on a Hadoop Cluster, Installing and Configuring Apache Airflow, Static or dynamic allocation of resources. However small overhead memory is also needed to determine the full memory request to YARN for each executor. To handle 300 gb data what would be the configuration for executor memory and driver memory. But just had a doubt, you didnt mention about the volume of data. http://spark.apache.org/docs/latest/configuration.html#dynamic-allocation, http://spark.apache.org/docs/latest/job-scheduling.html#resource-allocation-policy, https://blog.cloudera.com/blog/2015/03/how-to-tune-your-apache-spark-jobs-part-2/, http://spark.apache.org/docs/latest/cluster-overview.html. Any idea how to calculate spark.dynamicAllocation.maxExecutor in case of Dynamic Allocation. So we might think, more concurrent tasks for each executor will give better performance. Dynamic Allocation The values are picked up based on the requirement (size of data, amount of computations needed) and released after use. Nice article, We start with how to choose number of cores: Number of cores = Concurrent tasks an executor can run. An executor stays up for the if yes then how they divide the task on that worker node program faq. The time in which a job has to complete Spark is agnostic to a cluster manager as long as itcan acquire executor processes and those can communicate with each other.We areprimarily interested in Yarn as the cluster manager. standalone manager, Mesos, YARN). To conclude, if we need more control over the job execution time, monitor the job for unexpected data volume the static numbers would help. I mean we have one property to set shuffle partition i.e. These limits are for sharing between spark and other applications which run on YARN. And available RAM on each node is 63 GB. A spark cluster can run in either yarn clusteror yarn-client mode: yarn-client mode A driver runs on client process, Application Master is only used for requesting resources from YARN. Spark manages data using partitions that helps parallelize data processing with minimaldata shuffle across the executors. Here each application will get its own executor processes. For example, assume that i need an concurrent execution for 4 TB data. Imitation of Intelligence : Exploring Artificial Intelligence! Hey.. the article is really nice.. but i have a doubt. NIce Article and Great work!, Keeping all the things at one place, It would be good if you can add the spark settings, For ex: How to set the number of partitions. (Number of Executor/No of Nodes) X (Executor Memory) < (Node RAM 2 GB), no of cores per executor 3 From the above steps, it is clear that the number of executors and their memory setting play a major role in a spark job. Hi, Static or dynamic allocation of resources At this stage, this would lead to 21 GB, and then 19 as per our first calculation. Assumption all nodes has equal configuration. There are a few factors that we need to consider to decide the optimum numbers for the above three, like: The amount of data Any cluster manager can be used as long as the executor processes are running and they communicate with each other. For instance, an application will add 1 executor in the first round, and then 2, 4, 8 and so on executors in the subsequent rounds. Very nice article above!! This number comes from the ability of an executor to run parallel tasks and not from how many cores a system has. The magic number 5 comes to 3 (any number less than or equal to 5). Out of 18 we need 1 executor (java process) for Application Master in YARN. This helps the resources to be re-used for other applications. This is really a nice blog to read. Its such a wonderful read on Spark tutorial. Based on you inputs i have derived following final numbers Executors 2, Cores 1, Executor Memory 10.695 GB. I am also educating people on similar Spark Tutorial so if you are interested to know more you can watch this Spark training:-https://www.youtube.com/watch?v=dMDQz82FCqE, Hey It is really above article. The more cores we have, the more work we can do. Still 15/5 as calculated above. New Centers in Boston, MA, Seattle, WA, Dallas, TX and Washington DC. The unit of parallel execution is at the task level.All thetasks with-in a single stage can be executed in parallel. But if we are processing 20 to 30 GB data ,Is it really require to allocate this much core and memory per executor ? Note: Upper bound for the number of executors if dynamic allocation is enabled is infinity. To understand dynamic allocation, we need to have knowledge of the following properties: spark.dynamicAllocation.enabled when this is set to true we need not mention executors. Example we have 1 TB. Tasks are sent by SparkContext to the executors. This means that we can allocate specific number of cores for YARN based applications based on user access. So the number 5 stays same even if we have double (32) cores in the CPU. the number of jobs ready for the execution is 4. if yes then how they divide the task on that worker node program faq, Impala Load Balancing with Amazon Elastic Load Balancer. Running executors with too much memory often results in excessive garbagecollection delays. Resource Allocation is an important aspect during the execution of any spark job. Pingback: can we have more than one executor per application per node.? This would eventually be the number what we give at spark-submit in static way. executor memory 27.0, ## 3 cores and 29 GB available for JVM on each node 63/6 ~ 10. Keep sharing stuffs like this. There are two ways in which we configure the executor and core details to the Spark job. So final number is 17 executors, This 17 is the number we give to spark using num-executors while running from spark-submit shell command, From above step, we have 3 executorsper node. Task : A task is a unit of work that can be run on a partition of a distributed dataset andgets executed on a single executor. In a cluster where wehave other applications running and they also need cores to run the tasks, we need to make sure that we assign the cores at cluster level. we can increase/decrease.please give us fully clarity. no of executors 1 Overhead is 12*.07=.84. spark.dynamicAllocation.executorIdleTimeout, can we have more than one executor per application per node.? If not configured correctly, a spark job can consume entire cluster resources and make other applications starve for resources. Excellent explanation.I really appreciate your explanation on this blog.Expecting one blog from you how to set number of partition for shuffle for best optimization. Based on what research you came up with numbers? The formula for that overhead is max(384, .07 * spark.executor.memory), Calculating that overhead: .07 * 21 (Here 21 is calculated as above 63/3)= 1.47, Since 1.47 GB > 384 MB, the overhead is 1.47, Take the above from each 21 above => 21 1.47 ~ 19 GB, Final numbers Executors 17, Cores 5, Executor Memory 19 GB. So the request for the number of executors requested in each round increases exponentially from the previous round. When do we give away an executor is set using spark.dynamicAllocation.executorIdleTimeout. we have single node cluster 128 GB memory and 32 cores. So memory for each executor in each node is 63/3 = 21GB. ThankYou!!! driver-memory 8g, I appreciate your work on Spark. This blog helps to understand the basic flow in a Spark Application and then how to configure the number of executors, memory settings of each executors and the number of cores for a Spark Job. For optimal usage: However if dynamic allocation comes into picture, there would be different stages like the following: What is the number for executors to start with: Initial number of executors (spark.dynamicAllocation.initialExecutors) to start with. Any other than above references? So once the initial executor numbers are set, we go to min (spark.dynamicAllocation.minExecutors) and max (spark.dynamicAllocation.maxExecutors) numbers. In spark, this controls the number of parallel tasks an executor can run. But since we thought 10 is ok (assume little overhead), then we cannot switch the number of executors per node to 6 (like 63/10). Cluster Manager allocates resources across the other applications. Really nice informative article. Upstream or downstream application spark-submit master yarn \ Hey , Very nice explanation . Executor :An executor is a single JVM process which is launched for an application on a workernode. From the driver code, SparkContext connects to cluster manager (standalone/Mesos/YARN). The number ofexecutors for a spark application can be specified inside the SparkConf or via the flag num-executors from command-line. Spark acquires executors on nodes in cluster. Suppose I have 500gb,data ,16-cores,10-Nodes,100GB RAM.How can i calculate ,executor ,memory. yarn-cluster mode A driver runs inside application master process, client goes away once the application is initialized. Overhead is .07 * 10 = 700 MB. ## over head, 0.07X29 = ~ 2GB, so effective available is 27 GB for Executor At the starting of this blog, my expectation was to understand spark configuration based on the amount of data. A single node can run multiple executors andexecutors for an application can span multiple worker nodes. Hi Shalin, the numbers came from the initial hardware setup configuration and the formulae used to calculate the resources. So the optimal value is 5. Controlling the number ofexecutors dynamically: Then based on load (tasks pending) how many executors to request. So with 6 nodes, and 3 executors per node we get a total of 18 executors. Cluster Manager :An external service for acquiring resources on the cluster (e.g. In this scenario , what should be the combination? So we also need to change number of cores for each executor. They are: Different cases are discussed varying different parameters and arriving at different combinations as per user/data requirements. Now we try to understand, how to configure the best set of values to optimize a spark job. Static Allocation The values are given as part of spark-submit. Application code (jar/python files/python egg files) is sent to executors. This is mentioned in the document as a factor for deciding the Spark configuration but later in this document does not cover this factor. Number of cores of 5 is same for good concurrency as explained above. Ans: 3 Cores, 4 executors and 27 GB for RAM. default is spark.sql.shuffle.partiton = 200.what are the optimization way to increase and decrease this number.and on what basis There are a few factors that we need to consider todecide the optimum numbers for the above three, like: Lets start with some basic definitions of the terms used in handling Spark applications. But what in case of small cluster with 4 node each with 4 cores and 30GB of RAM. But research shows that any application with more than 5 concurrent tasks, would lead to a bad show. Can you solve these problem please. Coming to the next step, with 5 as cores per executor, and 15 as total available cores in one node (CPU) we come to3 executors per node which is 15/5. The above scenarios start with accepting number of cores as fixed and moving to the number of executors and memory. So how many nodes will required for certain amount of data. When to ask new executors or give away current executors: When do we request new executors (spark.dynamicAllocation.schedulerBacklogTimeout) This means that there have been pending tasks for this much duration. 6 cores, 24 GB RAM . First on each node, 1 core and 1 GB is needed for Operating System and Hadoop Daemons, so we have 15 cores, 63 GB RAM for each node. So rounding to 1GB as overhead, we get 10-1 = 9 GB, Final numbers Executors 35, Cores 5, Executor Memory 9 GB. And at the same time the performance want to show good. So with 3 cores, and 15 available cores we get 5 executors per node, 29 executors ( which is (5*6 -1)) andmemory is 63/5 ~ 12. Cores : A core is a basic computation unit of CPUand aCPU may have one or more cores to perform tasks at a given time. duration of the Spark Application and runs the tasks in multiple threads. Executor runs tasks and keeps data in memory or disk storage across them. At a specific point, the above property max comes into picture. What I can suggest a simple thumb rule is The reason is below: The static parameter numbers we give at spark-submit is for the entire job duration. So executor memory is 12 1 GB = 11 GB, Final Numbers are 29 executors, 3 cores, executor memory is 11 GB. so at that time how much hardware requirement minimum i required? Now for the first case, if we think we do not need 19 GB, and just 10 GB is sufficient based on the data size and computations involved, then following are the numbers: Number of executors for each node = 3. Number of executors for each node = 32/5 ~ 6, So total executors = 6 * 6 Nodes = 36. Eachapplication has its own executors. So this says that spark application can eat away all the resources if needed. By moving to dynamic, the resources would be used at the background and thejobs involving unexpected volumes might affect other applications. So each job carries data of 1 Tb for its execution. We need to calculate the number of executors on each node and then get the total number for the job. num-executors 20 executor-memory 6g executor-cores 2 queue quenemae_q1 conf spark.yarn.executor.memoryOverhead=2048 \ Then final number is 36 1(for AM) = 35, 6 executors for each node. Thanks .. it was very useful info, Could you kindly let me know the data that we can process with just 1 node with config: \ Because with 6 executors per node and 5 cores it comes down to 30 cores per node, when we only have 16 cores. . So we can create a spark_user and then give cores (min/max) for that user. 3 cores per executor, so 1 executor per node and 29 gb of Ram per executor The parallel task numbers etc are derived as per requirement and the references are provided in the blog. Partitions :A partition is a small chunk of a large distributed data set.
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