# 并发 async / await

有关路径操作函数的 `async def` 语法以及异步代码、并发和并行的一些背景知识。

## 赶时间吗？

<abbr title="too long; didn't read(长文警告)"><strong>TL;DR:</strong></abbr>

如果你正在使用第三方库，它们会告诉你使用 `await` 关键字来调用它们，就像这样：

```Python
results = await some_library()
```

然后，通过 `async def` 声明你的 *路径操作函数*：

```Python hl_lines="2"
@app.get('/')
async def read_results():
    results = await some_library()
    return results
```

/// note

         'msys2.tar.xz'); \
    Start-Process -FilePath \"C:\Program Files\7-Zip\7z.exe\" -ArgumentList 'x msys2.tar.xz -oC:\TEMP\msys2.tar' -Wait; \
    Start-Process -FilePath \"C:\Program Files\7-Zip\7z.exe\" -ArgumentList 'x C:\TEMP\msys2.tar -oC:\tools' -Wait; \
    $env:PATH = [Environment]::GetEnvironmentVariable('PATH', 'Machine') + ';C:\tools\msys64;C:\tools\msys64\usr\bin\'; \

				w := xioutil.NewDeadlineWorker(globalDriveConfig.GetMaxTimeout())
				return w.Run(func() error {
					wait := deleteCleanupSleeper.Timer(ctx)
					removeAll(pathJoin(drivePath, minioMetaTmpDeletedBucket, ddir))
					wait()
					return nil
				})
			})
		}(disk)
	}
	wg.Wait()
}

// nsScanner will start scanning buckets and send updated totals as they are traversed.

async def custom_http_exception_handler(request, exc):
    print(f"OMG! An HTTP error!: {repr(exc)}")
    return await http_exception_handler(request, exc)


@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request, exc):
    print(f"OMG! The client sent invalid data!: {exc}")
    return await request_validation_exception_handler(request, exc)


@app.get("/items/{item_id}")

Dann können wir einen `AsyncClient` mit der App erstellen und mit `await` asynchrone Requests an ihn senden.

{* ../../docs_src/async_tests/test_main.py hl[9:12] *}

Das ist das Äquivalent zu:

```Python
response = client.get('/')
```

... welches wir verwendet haben, um unsere Requests mit dem `TestClient` zu machen.

/// tip | "Tipp"

Beachten Sie, dass wir async/await mit dem neuen `AsyncClient` verwenden – der Request ist asynchron.

///

Then we can create an `AsyncClient` with the app, and send async requests to it, using `await`.

{* ../../docs_src/async_tests/test_main.py hl[9:12] *}

This is the equivalent to:

```Python
response = client.get('/')
```

...that we used to make our requests with the `TestClient`.

/// tip

Note that we're using async/await with the new `AsyncClient` - the request is asynchronous.

///

/// warning

import * as fs from 'fs'

async function modifyOpenAPIFile(filePath) {
  try {
    const data = await fs.promises.readFile(filePath)
    const openapiContent = JSON.parse(data)

    const paths = openapiContent.paths
    for (const pathKey of Object.keys(paths)) {
      const pathData = paths[pathKey]
      for (const method of Object.keys(pathData)) {
        const operation = pathData[method]
        if (operation.tags && operation.tags.length > 0) {

            te = null;
            thread = new Thread( this, name );
            thread.setDaemon( true );

            synchronized (thread) {
                thread.start();
                thread.wait( timeout );          /* wait for doConnect */

                switch (state) {
                    case 1: /* doConnect never returned */
                        state = 0;
                        thread = null;

   * is complete. It does so by using daemon threads and adding a shutdown hook to wait for their
   * completion.
   *
   * <p>This is mainly for fixed thread pools. See {@link Executors#newFixedThreadPool(int)}.
   *
   * @param executor the executor to modify to make sure it exits when the application is finished
   * @param terminationTimeout how long to wait for the executor to finish before terminating the
   *     JVM

   * @param timeoutDuration with timeoutUnit, the maximum length of time that callers are willing to
   *     wait on each method call to the proxy
   * @param timeoutUnit with timeoutDuration, the maximum length of time that callers are willing to
   *     wait on each method call to the proxy
   * @return a time-limiting proxy
   * @throws IllegalArgumentException if {@code interfaceType} is a regular class, enum, or