tillrohrmann commented on a change in pull request #10999: [FLINK-15143] Docs for FLIP-49 TM memory model and configuration guide URL: https://github.com/apache/flink/pull/10999#discussion_r376656155
########## File path: docs/ops/memory/mem_detail.md ########## @@ -0,0 +1,149 @@ +--- +title: "Detailed Memory Model" +nav-parent_id: ops_mem +nav-pos: 2 +--- +<!-- +Licensed to the Apache Software Foundation (ASF) under one +or more contributor license agreements. See the NOTICE file +distributed with this work for additional information +regarding copyright ownership. The ASF licenses this file +to you under the Apache License, Version 2.0 (the +"License"); you may not use this file except in compliance +with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, +software distributed under the License is distributed on an +"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +KIND, either express or implied. See the License for the +specific language governing permissions and limitations +under the License. +--> + +This section gives a detailed description of all components in Flink’s memory model of task executor. +Check [memory configuration guide](mem_setup.html) for the basic memory setup. + +* toc +{:toc} + +## Overview + +<br /> +<center> + <img src="{{ site.baseurl }}/fig/detailed-mem-model.svg" width="300px" alt="Simple memory model" usemap="#simple-mem-model"> +</center> +<br /> + +The following table lists all memory components, depicted above, and references Flink configuration options +which affect the size of the respective components: + +| **Component** | **Configuration options** | **Description** | +| :-------------------------------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | +| [Framework Heap Memory](#framework-memory) | [`taskmanager.memory.framework.heap.size`](../config.html#taskmanager-memory-framework-heap-size) | JVM heap memory dedicated to Flink framework (advanced option) | +| [Task Heap Memory](mem_setup.html#task-operator-heap-memory) | [`taskmanager.memory.task.heap.size`](../config.html#taskmanager-memory-task-heap-size) | JVM heap memory dedicated to Flink application to run operators and user code | +| [Managed memory](mem_setup.html#managed-memory) | [`taskmanager.memory.managed.size`](../config.html#taskmanager-memory-managed-size) <br/> [`taskmanager.memory.managed.fraction`](../config.html#taskmanager-memory-managed-fraction) | Native memory managed by Flink, reserved for sorting, hash tables, caching of intermediate results and RocksDB state backend | +| [Framework Off-heap Memory](#framework-memory) | [`taskmanager.memory.framework.off-heap.size`](../config.html#taskmanager-memory-framework-off-heap-size) | [Off-heap direct (or native) memory](mem_setup.html#configure-off-heap-memory-direct-or-native) dedicated to Flink framework (advanced option) | +| [Task Off-heap Memory](mem_setup.html#configure-off-heap-memory-direct-or-native) | [`taskmanager.memory.task.off-heap.size`](../config.html#taskmanager-memory-task-off-heap-size) | [Off-heap direct (or native) memory](mem_setup.html#configure-off-heap-memory-direct-or-native) dedicated to Flink application to run operators | +| Network Memory | [`taskmanager.memory.network.min`](../config.html#taskmanager-memory-network-min) <br/> [`taskmanager.memory.network.max`](../config.html#taskmanager-memory-network-max) <br/> [`taskmanager.memory.network.fraction`](../config.html#taskmanager-memory-network-fraction) | Direct memory reserved for data record exchange between tasks (e.g. buffering for the transfer over the network), it is a [capped fractionated component](#capped-fractionated-components) of the [total Flink memory](mem_setup.html#configure-total-memory) | +| [JVM metaspace](#jvm-parameters) | [`taskmanager.memory.jvm-metaspace.size`](../config.html#taskmanager-memory-jvm-metaspace-size) | Metaspace size of the Flink JVM process | +| JVM Overhead | [`taskmanager.memory.jvm-overhead.min`](../config.html#taskmanager-memory-jvm-overhead-min) <br/> [`taskmanager.memory.jvm-overhead.max`](../config.html#taskmanager-memory-jvm-overhead-max) <br/> [`taskmanager.memory.jvm-overhead.fraction`](../config.html#taskmanager-memory-jvm-overhead-fraction) | Native memory reserved for other JVM overhead: e.g. thread stacks, code cache, garbage collection space etc, it is a [capped fractionated component](#capped-fractionated-components) of the [total process memory](mem_setup.html#configure-total-memory) | +{:.table-bordered} +<br/> + +As you can see, the size of some memory components can be simply set by the respective option. +Other components can be tuned using multiple options. + +## Framework Memory + +The *framework heap memory* and *framework off-heap memory* options are not supposed to be changed without a good reason. +Adjust them only if you are sure that Flink needs more memory for some internal data structures or operations. +It can be related to a particular deployment environment or job structure, like high parallelism. +In addition, Flink dependencies, such as Hadoop may consume more direct or native memory in certain setups. + +<span class="label label-info">Note</span> Neither heap nor off-heap versions of framework and task memory are currently isolated within Flink. +The separation of framework and task memory can be used in future releases for further optimizations. + +## Capped Fractionated Components + +This section describes the configuration details of the following options which can be a fraction of a certain +[total memory](mem_setup.html#configure-total-memory): + +* *Network memory* can be a fraction of the *total Flink memory* +* *JVM overhead* can be a fraction of the *total process memory* + +See also [detailed memory model](#overview). + +The size of those components always has to be between its maximum and minimum value, otherwise Flink startup will fail. +The maximum and minimum values have defaults or can be explicitly set by corresponding configuration options. +For example, if only the following memory options are set: +- total Flink memory = 1000Mb, +- network min = 64Mb, +- network max = 128Mb, +- network fraction = 0.1 + +then the network memory will be 1000Mb x 0.1 = 100Mb which is within the range 64-128Mb. + +Notice if you configure the same maximum and minimum value it effectively means that its size is fixed to that value. + +If the component memory is not explicitly configured, then Flink will use the fraction to calculate the memory size +based on the total memory. The calculated value is capped by its corresponding min/max options. +For example, if only the following memory options are set: +- total Flink memory = 1000Mb, +- network min = 128Mb, +- network max = 256Mb, +- network fraction = 0.1 + +then the network memory will be 128Mb because the size derived from fraction is 100Mb and it is less than the minimum. + +It can also happen that the fraction is ignored if the sizes of the total memory and its other components are defined. +In this case, the network memory is the rest of the total memory. The derived value still has to be within its min/max +range otherwise the configuration fails. For example, suppose only the following memory options are set: +- total Flink memory = 1000Mb, +- task heap = 100Mb, +- network min = 64Mb, +- network max = 256Mb, +- network fraction = 0.1 + +All other components of the total Flink memory have default values, including the default managed memory fraction. +Then the network memory is not the fraction (1000Mb x 0.1 = 100Mb) but the rest of the total Flink memory +which will either be within the range 64-256Mb or fail. + +## JVM Parameters + +Flink explicitly adds the following memory related JVM arguments while starting the task executor process, +based on the configured or derived memory component sizes: + +| **JVM Arguments** | **Value** | +| :---------------------------------------- | :----------------------------------------- | +| *-Xmx* and *-Xms* | Framework + Task Heap Memory | +| *-XX:MaxDirectMemorySize* | Framework + Task Off-Heap + Network Memory | +| *-XX:MaxMetaspaceSize* | JVM Metaspace | +{:.table-bordered} +<br/> + +See also [detailed memory model](#overview). + +## Local Execution +If you start Flink locally on your machine as a single java program without creating a cluster (e.g. from your IDE) Review comment: ```suggestion If you start Flink locally on your machine as a single java program without creating a cluster (e.g. from your IDE), ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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