```

     * 因此，`main:app` 中的冒号相当于 `from main import app` 中的 Python `import` 部分。

* `--workers`：要使用的worker进程数量，每个进程将运行一个 Uvicorn worker进程，在本例中为 4 个worker进程。

* `--worker-class`：在worker进程中使用的与 Gunicorn 兼容的工作类。
     * 这里我们传递了 Gunicorn 可以导入和使用的类：

         ```Python
         import uvicorn.workers.UvicornWorker
         ```

* `--bind`：这告诉 Gunicorn 要监听的 IP 和端口，使用冒号 (`:`) 分隔 IP 和端口。

```console
$ gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:80

[19499] [INFO] Starting gunicorn 20.1.0
[19499] [INFO] Listening at: http://0.0.0.0:80 (19499)
[19499] [INFO] Using worker: uvicorn.workers.UvicornWorker
[19511] [INFO] Booting worker with pid: 19511
[19513] [INFO] Booting worker with pid: 19513
[19514] [INFO] Booting worker with pid: 19514

default            reviews-v3-5b9bd44f4-z9ms4                           10.244.1.43 ambient-worker        None                                HBONE
default            sleep-7656cf8794-lxcmx                               10.244.2.58 ambient-worker2       None                                HBONE

```console
$ gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:80

[19499] [INFO] Starting gunicorn 20.1.0
[19499] [INFO] Listening at: http://0.0.0.0:80 (19499)
[19499] [INFO] Using worker: uvicorn.workers.UvicornWorker
[19511] [INFO] Booting worker with pid: 19511
[19513] [INFO] Booting worker with pid: 19513
[19514] [INFO] Booting worker with pid: 19514

!!! tip
    Don't worry if some of these items about **containers**, Docker, or Kubernetes don't make a lot of sense yet.

    I'll tell you more about container images, Docker, Kubernetes, etc. in a future chapter: [FastAPI in Containers - Docker](docker.md){.internal-link target=_blank}.

## Previous Steps Before Starting

```console
$ gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:80

[19499] [INFO] Starting gunicorn 20.1.0
[19499] [INFO] Listening at: http://0.0.0.0:80 (19499)
[19499] [INFO] Using worker: uvicorn.workers.UvicornWorker
[19511] [INFO] Booting worker with pid: 19511
[19513] [INFO] Booting worker with pid: 19513
[19514] [INFO] Booting worker with pid: 19514

default   details-v1-698d88b-krdw7       10.244.2.55 ambient-worker2 None     HBONE
default   httpbin-7447985f87-t8hv7       10.244.1.40 ambient-worker  None     TCP
default   productpage-v1-675fc69cf-kkrm2 10.244.2.56 ambient-worker2 None     HBONE
default   ratings-v1-6484c4d9bb-8xc2r    10.244.2.57 ambient-worker2 None     HBONE
default   reviews-v1-5b5d6494f4-c7z5w    10.244.1.41 ambient-worker  None     HBONE

```console
$ gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:80

[19499] [INFO] Starting gunicorn 20.1.0
[19499] [INFO] Listening at: http://0.0.0.0:80 (19499)
[19499] [INFO] Using worker: uvicorn.workers.UvicornWorker
[19511] [INFO] Booting worker with pid: 19511
[19513] [INFO] Booting worker with pid: 19513
[19514] [INFO] Booting worker with pid: 19514

		workers = workers[:len(workers)-1]
		worker <- expiryOp(nil)
		es.stats.workers.Add(-1)
	}
	// Atomically replace workers.
	es.workers.Store(&workers)
}

// Worker handles 4 types of expiration tasks.
// 1. Expiry of objects, includes regular and transitioned objects
// 2. Expiry of noncurrent versions due to NewerNoncurrentVersions

In those cases, you can use the **official Docker image** that includes **Gunicorn** as a process manager running multiple **Uvicorn worker processes**, and some default settings to adjust the number of workers based on the current CPU cores automatically. I'll tell you more about it below in [Official Docker Image with Gunicorn - Uvicorn](#official-docker-image-with-gunicorn-uvicorn).