# 最初のステップ

最もシンプルなFastAPIファイルは以下のようになります:

{* ../../docs_src/first_steps/tutorial001.py *}

これを`main.py`にコピーします。

ライブサーバーを実行します:

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
<span style="color: green;">INFO</span>:     Started reloader process [28720]

    }

    /**
     * Test: Thread-safe listener invocation during connection
     * Verifies that listeners can be added while connect() is executing
     */
    @Test
    public void testConcurrentListenerInvocation() throws Exception {
        // This test verifies CopyOnWriteArrayList allows safe iteration
        assertTrue("OnConnectListener list should be thread-safe",

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Marks an event subscriber method as being thread-safe. This annotation indicates that EventBus
 * may invoke the event subscriber simultaneously from multiple threads.
 *
 * <p>This does not mark the method, and so should be used in combination with {@link Subscribe}.
 *

                null);

        // Wait for expiration
        try {
            Thread.sleep(150);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }

        HandleInfo info = manager.getHandleForReconnect("/test/file.txt");
        assertNull(info);
    }

    @Test

import jakarta.annotation.PreDestroy;
import jakarta.annotation.Resource;

/**
 * IndexUpdater is responsible for updating the search index with crawled document data.
 * This class extends Thread and continuously processes access results from the crawler,
 * transforms them into indexed documents, and updates the OpenSearch index.
 *
 * <p>The updater performs the following key operations:
 * <ul>

     *            the length of time to sleep in milliseconds
     * @throws InterruptedRuntimeException
     *             if any thread has interrupted the current thread.
     */
    public static void sleep(final long millis) {
        if (millis < 1L) {
            return;
        }
        try {
            Thread.sleep(millis);
        } catch (final InterruptedException e) {
            throw new InterruptedRuntimeException(e);
        }

func (cr *s3ChunkedReader) Read(buf []byte) (n int, err error) {
	if cr.err != nil {
		if cr.debug {
			fmt.Printf("s3ChunkedReader: Returning err: %v (%T)\n", cr.err, cr.err)
		}
		return 0, cr.err
	}
	defer func() {
		if err != nil && err != io.EOF {
			if cr.debug {
				fmt.Println("Read err:", err)
			}
		}
	}()
	// First, if there is any unread data, copy it to the client

import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import org.jspecify.annotations.Nullable;

/**
 * Weak reference with a {@code finalizeReferent()} method which a background thread invokes after
 * the garbage collector reclaims the referent. This is a simpler alternative to using a {@link
 * ReferenceQueue}.
 *
 * @author Bob Lee
 * @since 2.0
 */
@J2ktIncompatible
@GwtIncompatible

  class Interruptenator extends Thread {
    final AtomicBoolean shutdown;

    Interruptenator(Thread interruptee) {
      this(interruptee, new AtomicBoolean(false));
    }

    @SuppressWarnings("ThreadPriorityCheck") // TODO: b/175898629 - Consider onSpinWait.
    Interruptenator(Thread interruptee, AtomicBoolean shutdown) {
      super(
          new Runnable() {

```console
$ uvicorn main:app --reload

INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [28720]
INFO:     Started server process [28722]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
```

</div>

<details markdown="1">
<summary>Про команди <code>uvicorn main:app --reload</code>...</summary>