h.logChMu.Lock()
	xioutil.SafeClose(h.logCh)
	h.logCh = nil
	h.logChMu.Unlock()

	if h.producer != nil {
		h.producer.Close()
		h.client.Close()
	}

	// Wait for messages to be sent...
	h.wg.Wait()
}

// New initializes a new logger target which
// sends log over http to the specified endpoint
func New(config Config) *Target {
	target := &Target{

    return {"item_id": item_id, "q": q}
```

<details markdown="1">
<summary>Або використайте <code>async def</code>...</summary>

Якщо ваш код використовує `async` / `await`, скористайтеся `async def`:

```Python hl_lines="9  14"
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def read_root():

	}

	var i int
	for toExpire := range expireCh {
		select {
		case <-ctx.Done():
			return
		default:
		}
		if i > 0 {
			if wait := globalBatchConfig.ExpirationWait(); wait > 0 {
				time.Sleep(wait)
			}
		}
		i++
		wk.Take()
		go func(toExpire []expireObjInfo) {
			defer wk.Give()

			toExpireAll := make([]ObjectInfo, 0, len(toExpire))

			K8sServiceAccountPath: tempK8sSvcAcctDir,
		},
	}

	ctx, cancel := context.WithCancel(context.Background())
	wg := sync.WaitGroup{}

	wg.Add(1)
	defer func() {
		cancel()
		wg.Wait()
	}()
	go func() {
		startInstallServer(ctx, &installConfig, t)
		wg.Done()
	}()

	resultFile := tempCNIConfDir + "/" + resultFileName
	if chainedCNIPlugin && delayedConfFile != "" {

@REM
@REM   JAVA_HOME           (Optional) Points to a Java installation.
@REM   MAVEN_BATCH_ECHO    (Optional) Set to 'on' to enable the echoing of the batch commands.
@REM   MAVEN_BATCH_PAUSE   (Optional) set to 'on' to wait for a key stroke before ending.
@REM   MAVEN_OPTS          (Optional) Java runtime options used when Maven is executed.
@REM   MAVEN_SKIP_RC       (Optional) Flag to disable loading of mavenrc files.

			}, nil
		}))
		errFatal(err)
	}
	const payloadSize = 512
	rng := rand.New(rand.NewSource(time.Now().UnixNano()))
	payload := make([]byte, payloadSize)
	_, err = rng.Read(payload)
	errFatal(err)

	// Wait for all to connect
	// Parallel writes per server.
	b.Run("bytes", func(b *testing.B) {
		for par := 1; par <= 32; par *= 2 {
			b.Run("par="+strconv.Itoa(par*runtime.GOMAXPROCS(0)), func(b *testing.B) {

	var wg sync.WaitGroup
	wg.Add(1)
	defer func() {
		close(stopDraining)
		wg.Wait()
	}()
	go func() {
		defer wg.Done()
		for {
			select {
			case <-stopDraining:
				return
			default:
				if cap(c.outQueue)-len(c.outQueue) > 100 {
					// Queue is not full, wait a bit.
					time.Sleep(1 * time.Millisecond)
					continue
				}
				select {

**FastAPI** 会创建一个 `BackgroundTasks` 类型的对象并作为该参数传入。

## 创建一个任务函数

创建要作为后台任务运行的函数。

它只是一个可以接收参数的标准函数。

它可以是 `async def` 或普通的 `def` 函数，**FastAPI** 知道如何正确处理。

在这种情况下，任务函数将写入一个文件（模拟发送电子邮件）。

由于写操作不使用 `async` 和 `await`，我们用普通的 `def` 定义函数：

```Python hl_lines="6-9"
{!../../docs_src/background_tasks/tutorial001.py!}
```

## 添加后台任务

在你的 *路径操作函数* 里，用 `.add_task()` 方法将任务函数传到 *后台任务* 对象中：

```Python hl_lines="14"

				reqInfo := &logger.ReqInfo{}
				reqInfo.AppendTags("targetID", id.String())
				logger.LogOnceIf(logger.SetReqInfo(context.Background(), reqInfo), logSubsys, err, id.String())
			}
		}(id, target)
	}
	wg.Wait()
	list.totalEvents.Add(1)
}

func (list *TargetList) sendAsync(event Event, targetIDset TargetIDSet) {
	select {
	case list.queue <- asyncEvent{
		ev:        event,
		targetSet: targetIDset.Clone(),

			if val := globalServiceFreeze.Load(); val != nil {
				if unlock, ok := val.(chan struct{}); ok && unlock != nil {
					// Wait until unfrozen.
					select {
					case <-unlock:
					case <-r.Context().Done():
						// if client canceled we don't need to wait here forever.
						return
					}
				}
			}
		}

		globalHTTPStats.addRequestsInQueue(1)