### Creating the `Settings` only once with `lru_cache` { #creating-the-settings-only-once-with-lru-cache }

Reading a file from disk is normally a costly (slow) operation, so you probably want to do it only once and then reuse the same settings object, instead of reading it for each request.

But every time we do:

```Python
Settings()

* Feel free to comment in the PR to ask for more information, to suggest changes, etc.
* Once you think the PR is ready, move it in the internal GitHub project for me to review it.

## FastAPI People PRs

Every month, a GitHub Action updates the FastAPI People data. Those PRs look like this one: [👥 Update FastAPI People](https://github.com/fastapi/fastapi/pull/11669).

  }

  public void testExecutorOnlyCalledOnce() throws Exception {
    TestService service = new TestService();
    service.startAsync().awaitRunning();
    // It should be called once during startup.
    assertEquals(1, service.numberOfTimesExecutorCalled.get());
    for (int i = 1; i < 10; i++) {
      service.runFirstBarrier.await();
      assertEquals(i, service.numberOfTimesRunCalled.get());

  }

  public void testExecutorOnlyCalledOnce() throws Exception {
    TestService service = new TestService();
    service.startAsync().awaitRunning();
    // It should be called once during startup.
    assertEquals(1, service.numberOfTimesExecutorCalled.get());
    for (int i = 1; i < 10; i++) {
      service.runFirstBarrier.await();
      assertEquals(i, service.numberOfTimesRunCalled.get());

   * segments, each governed by its own write lock. The segment lock is taken once for each explicit
   * write, and twice for each cache loading computation (once prior to loading the new value, and
   * once after loading completes). Much internal cache management is performed at the segment

But here's the key point.

The security and dependency injection stuff is written once.

And you can make it as complex as you want. And still, have it written only once, in a single place. With all the flexibility.

But you can have thousands of endpoints (*path operations*) using the same security system.

    NullPointerTester tester = new NullPointerTester();
    tester.testAllPublicInstanceMethods(new FakeTicker());
  }

  @GwtIncompatible // java.time.Duration
  @IgnoreJRERequirement // TODO: b/288085449 - Remove this once we use library-desugaring scents.
  public void testAdvance() {
    FakeTicker ticker = new FakeTicker();
    assertEquals(0, ticker.read());
    assertThat(ticker.advance(10)).isSameInstanceAs(ticker);

     * Returns a newly-created immutable map, using the last value for any key that was added more
     * than once. The iteration order of the returned map is the order in which entries were
     * inserted into the builder, unless {@link #orderEntriesByValue} was called, in which case
     * entries are sorted by value. If a key was added more than once, it appears in iteration order

  - If you work for a company that wants to allow you to contribute your work,
    then you'll need to sign a [corporate CLA][].

You generally only need to submit a CLA once, so if you've already submitted
one (even if it was for a different project), you probably don't need to do it
again.

[individual CLA]: https://cla.developers.google.com/about/google-individual

You can use the property `.openapi_schema` as a "cache", to store your generated schema.

That way, your application won't have to generate the schema every time a user opens your API docs.

It will be generated only once, and then the same cached schema will be used for the next requests.

{* ../../docs_src/extending_openapi/tutorial001_py310.py hl[13:14,25:26] *}

### Override the method { #override-the-method }