# 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

    callback.await(server.url("/a")).assertBody("abc")
    client.newCall(Request.Builder().url(server.url("/b")).build()).enqueue(callback)
    callback.await(server.url("/b")).assertBody("def")
    client.newCall(Request.Builder().url(server.url("/c")).build()).enqueue(callback)
    callback.await(server.url("/c")).assertBody("ghi")

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

    }
  }

  /**
   * Like [Object.wait], but throws an [InterruptedIOException] when interrupted instead of the more
   * awkward [InterruptedException].
   */
  @Throws(InterruptedIOException::class)
  internal fun waitForIo() {
    try {
      condition.await()
    } catch (_: InterruptedException) {

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) {

			label.IoIstioDataplaneMode.Name, constants.DataplaneModeAmbient)), metav1.PatchOptions{})
	assert.NoError(t, err)

	// wait for an update event
	mt.Assert(EventTotals.Name(), map[string]string{"type": "update"}, monitortest.AtLeast(2))

	// wait for the pod to be annotated
	// after Pod annotated, another update event will be triggered.
	assertPodAnnotated(t, client, pod)

	// Assert expected calls actually made

import time

from fastapi import FastAPI, Request

app = FastAPI()


@app.middleware("http")
async def add_process_time_header(request: Request, call_next):
    start_time = time.perf_counter()
    response = await call_next(request)
    process_time = time.perf_counter() - start_time
    response.headers["X-Process-Time"] = str(process_time)

		},
		{
			[]clause.Interface{clause.Select{}, clause.From{}, clause.Locking{Strength: clause.LockingStrengthUpdate, Options: clause.LockingOptionsNoWait}},
			"SELECT * FROM `users` FOR UPDATE NOWAIT", nil,
		},
		{
			[]clause.Interface{clause.Select{}, clause.From{}, clause.Locking{Strength: clause.LockingStrengthUpdate, Options: clause.LockingOptionsSkipLocked}},
			"SELECT * FROM `users` FOR UPDATE SKIP LOCKED", nil,