1996fanrui commented on a change in pull request #9454: [FLINK-13644][docs-zh]
Translate "State Backends" page into Chinese
URL: https://github.com/apache/flink/pull/9454#discussion_r315496929
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File path: docs/ops/state/state_backends.zh.md
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@@ -22,114 +22,111 @@ specific language governing permissions and limitations
under the License.
-->
-Programs written in the [Data Stream API]({{ site.baseurl
}}/dev/datastream_api.html) often hold state in various forms:
+用 [Data Stream API]({{ site.baseurl }}/zh/dev/datastream_api.html)
编写的程序通常以各种形式保存状态：
-- Windows gather elements or aggregates until they are triggered
-- Transformation functions may use the key/value state interface to store
values
-- Transformation functions may implement the `CheckpointedFunction` interface
to make their local variables fault tolerant
+- 在 Window 触发之前要么收集元素、要么聚合
+- 转换函数可以使用 key/value 格式的状态接口来存储状态
+- 转换函数可以实现 `CheckpointedFunction` 接口，使其本地变量具有容错能力
-See also [state section]({{ site.baseurl }}/dev/stream/state/index.html) in
the streaming API guide.
+另请参阅 Streaming API 指南中的 [状态部分]({{ site.baseurl
}}/zh/dev/stream/state/index.html) 。
-When checkpointing is activated, such state is persisted upon checkpoints to
guard against data loss and recover consistently.
-How the state is represented internally, and how and where it is persisted
upon checkpoints depends on the
-chosen **State Backend**.
+CheckPoint 开启时，CheckPoint 持续地进行来防止数据丢失，并且能够完整地恢复。
+在 Flink 内部以及 CheckPoint 上，状态如何存储以及存储在哪里取决于选择的 **State Backend**。
* ToC
{:toc}
-## Available State Backends
+## 可用的 State Backends
-Out of the box, Flink bundles these state backends:
+Flink 内置了以下这些开箱即用的 state backends ：
- *MemoryStateBackend*
- *FsStateBackend*
- *RocksDBStateBackend*
-If nothing else is configured, the system will use the MemoryStateBackend.
+如果不设置，默认使用 MemoryStateBackend。
-### The MemoryStateBackend
+### MemoryStateBackend
-The *MemoryStateBackend* holds data internally as objects on the Java heap.
Key/value state and window operators hold hash tables
-that store the values, triggers, etc.
+*MemoryStateBackend* 将数据存储在 Java 堆中。 Key/value 的状态值和窗口算子的触发器都是通过 hash table
来存储。
-Upon checkpoints, this state backend will snapshot the state and send it as
part of the checkpoint acknowledgement messages to the
-JobManager (master), which stores it on its heap as well.
+在 CheckPoint 时，State Backend 对状态进行快照，并将快照信息作为 CheckPoint 应答消息的一部分发送给
JobManager(master)，同时 JobManager 也将快照信息存储在堆内存中。
-The MemoryStateBackend can be configured to use asynchronous snapshots. While
we strongly encourage the use of asynchronous snapshots to avoid blocking
pipelines, please note that this is currently enabled
-by default. To disable this feature, users can instantiate a
`MemoryStateBackend` with the corresponding boolean flag in the constructor set
to `false`(this should only used for debug), e.g.:
+MemoryStateBackend 能配置异步快照。强烈建议使用异步快照来防止数据流阻塞，注意，异步快照默认是开启的。
+用户可以在实例化 `MemoryStateBackend` 的时候，将相应布尔类型的构造参数设置为 `false` 来关闭异步快照（仅在 debug
的时候使用），例如：
{% highlight java %}
new MemoryStateBackend(MAX_MEM_STATE_SIZE, false);
{% endhighlight %}
-Limitations of the MemoryStateBackend:
+MemoryStateBackend 的限制：
- - The size of each individual state is by default limited to 5 MB. This
value can be increased in the constructor of the MemoryStateBackend.
- - Irrespective of the configured maximal state size, the state cannot be
larger than the akka frame size (see [Configuration]({{ site.baseurl
}}/ops/config.html)).
- - The aggregate state must fit into the JobManager memory.
+ - 默认情况下，每个独立的状态大小限制是 5 MB。在 MemoryStateBackend 的构造器中可以增加其大小。
+ - 无论配置的 `MAX_MEM_STATE_SIZE` 有多大，都不能大于 akka frame 大小（看[配置参数]({{ site.baseurl
}}/zh/ops/config.html)）。
+ - 聚合后的状态大小必须小于 JobManager 的内存。
Review comment:
聚合后的状态必须能够放进 JobManager 的内存中。
去掉了老师回复中的 “大小” 二字
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