* Others...

## Replication - Processes and Memory { #replication-processes-and-memory }

With a FastAPI application, using a server program like the `fastapi` command that runs Uvicorn, running it once in **one process** can serve multiple clients concurrently.

But in many cases, you will want to run several worker processes at the same time.

### Multiple Processes - Workers { #multiple-processes-workers }

graph TB

common_parameters(["common_parameters"])
read_items["/items/"]
read_users["/users/"]

common_parameters --> read_items
common_parameters --> read_users
```

This way you write shared code once and **FastAPI** takes care of calling it for your *path operations*.

/// check

Notice that you don't have to create a special class and pass it somewhere to **FastAPI** to "register" it or anything similar.

* Data "<abbr title="converting the string that comes from an HTTP request into Python data">parsing</abbr>"
* Data validation
* API annotation and automatic documentation

And you only have to declare them once.

  public TestThread(L lockLikeObject, String threadName) {
    super(threadName);
    this.lockLikeObject = checkNotNull(lockLikeObject);
    start();
  }

  /*
   * TODO: b/318391980 - Once we test only under Java 20 and higher, avoid calling Thread.stop. As
   * of Java 20, it always throws an exception, and as of Java 26, the method does not even exist.
   * For now, we continue using it to clean up under older JDKs.

    cache.close()
    createNewCache()

    // The journal will have no record that 'a' was removed. It will have an entry for 'a', but when
    // it tries to read the cache files, it will find they were deleted. Once it encounters an entry
    // with missing cache files, it should remove it from the cache entirely.
    assertThat(cache.size()).isEqualTo(4)
    assertThat(cache["a"]).isNull()
    assertThat(cache.size()).isEqualTo(2)

            return false;
          }

          @Override
          public Integer getResult() {
            return seen;
          }
        };
    assertEquals(
        "processLine was called more than once",
        1,
        CharStreams.readLines(r, alwaysFalse).intValue());

    // Test a LineProcessor that always returns true.
    r = new StringReader(text);
    LineProcessor<Integer> alwaysTrue =

   */
  void put(K key, V value);

  /**
   * Copies all of the mappings from the specified map to the cache. The effect of this call is
   * equivalent to that of calling {@code put(k, v)} on this map once for each mapping from key
   * {@code k} to value {@code v} in the specified map. The behavior of this operation is undefined
   * if the specified map is modified while the operation is in progress.
   *
   * @since 12.0

    this.function = checkNotNull(function);
  }

  @Override
  @SuppressWarnings({
    "CatchingUnchecked", // sneaky checked exception
    "nullness", // TODO(b/147136275): Remove once our checker understands & and |.
  })
  public final void run() {
    @RetainedLocalRef ListenableFuture<? extends I> localInputFuture = inputFuture;
    @RetainedLocalRef F localFunction = function;

            return false;
          }

          @Override
          public Integer getResult() {
            return seen;
          }
        };
    assertEquals(
        "processLine was called more than once",
        1,
        CharStreams.readLines(r, alwaysFalse).intValue());

    // Test a LineProcessor that always returns true.
    r = new StringReader(text);
    LineProcessor<Integer> alwaysTrue =

        assertSame(fe3, it.next(), "Third element from second page");

        // After last element, hasNext should be false and calling close() should send Smb2CloseRequest once
        assertFalse(it.hasNext(), "Iterator should be exhausted");

        // Close explicitly to exercise doCloseInternal
        it.close();