---
title: "通用配置"
weight: 1
type: docs
aliases:
  - /zh/deployment/filesystems/common.html
  - /zh/ops/filesystems.html
---
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# 通用配置

Apache Flink 提供了一些对所有文件系统均适用的基本配置。



## 默认文件系统

如果文件路径未明确指定文件系统的 scheme（和 authority），将会使用默认的 scheme（和 authority）：

```yaml
fs.default-scheme: <default-fs>
```

例如默认的文件系统配置为 `fs.default-scheme: hdfs://localhost:9000/`，则文件路径 `/user/hugo/in.txt` 将被处理为 `hdfs://localhost:9000/user/hugo/in.txt`。

## 连接限制

如果文件系统不能处理大量并发读/写操作或连接，可以为文件系统同时打开的总连接数设置上限。

例如在一个大型 Flink 任务建立 checkpoint 时，具有少量 RPC handler 的小型 HDFS 集群可能会由于建立了过多的连接而过载。

要限制文件系统的连接数，可将下列配置添加至 Flink 配置中。设置限制的文件系统由其 scheme 指定：

```yaml
fs.<scheme>.limit.total: (数量，0/-1 表示无限制)
fs.<scheme>.limit.input: (数量，0/-1 表示无限制)
fs.<scheme>.limit.output: (数量，0/-1 表示无限制)
fs.<scheme>.limit.timeout: (毫秒，0 表示无穷)
fs.<scheme>.limit.stream-timeout: (毫秒，0 表示无穷)
```

输入和输出连接（流）的数量可以分别进行限制（`fs.<scheme>.limit.input` 和 `fs.<scheme>.limit.output`），也可以限制并发流的总数（`fs.<scheme>.limit.total`）。如果文件系统尝试打开更多的流，操作将被阻塞直至某些流关闭。如果打开流的时间超过 `fs.<scheme>.limit.timeout`，则流打开失败。

为避免不活动的流占满整个连接池（阻止新连接的建立），可以在配置中添加无活动超时时间，如果连接至少在 `fs.<scheme>.limit.stream-timeout` 时间内没有读/写操作，则连接会被强制关闭。

连接数是按每个 TaskManager/文件系统来进行限制的。因为文件系统的创建是按照 scheme 和 authority 进行的，所以不同的 authority 具有独立的连接池，例如 `hdfs://myhdfs:50010/` 和 `hdfs://anotherhdfs:4399/` 会有单独的连接池。

## File System Factory Priority

When multiple `FileSystemFactory` implementations are available for the same URI scheme (for example, during a migration between file system backends), Flink resolves the conflict using a priority mechanism. The factory with the highest priority is selected.

Each factory declares a default priority via its `getPriority()` method (default `0`). You can override the priority for any factory through configuration:

```yaml
fs.<scheme>.priority.<factoryClassName>: <integer>
```

Higher values indicate higher priority. When the configuration key is not set, the factory's declared priority is used.

If two factories end up with the same priority, the winner depends on classloading order, which is non-deterministic. Flink logs a warning in this case. Set explicit priorities to ensure deterministic behavior.

**Example:** Suppose two S3 factory implementations are on the classpath. To select the Hadoop-based factory over the Presto-based one (default priority is zero):

```yaml
fs.s3.priority.org.apache.flink.fs.s3.hadoop.S3FileSystemFactory: 1
```

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