*
 * <p>
 * Toolchains can be obtained through the {@link org.apache.maven.api.services.ToolchainManager ToolchainManager}
 * service. This service provides methods to retrieve and manage toolchains defined
 * in the Maven configuration.
 * </p>
 *
 * <p>
 * The following are key functionalities provided by the Toolchain interface:</p><ul>

Первая часть функции, до `yield`, будет выполнена до запуска приложения.

А часть после `yield` будет выполнена после завершения работы приложения.

### Асинхронный менеджер контекста { #async-context-manager }

Если присмотреться, функция декорирована `@asynccontextmanager`.

Это превращает функцию в «асинхронный менеджер контекста».

{* ../../docs_src/events/tutorial003_py39.py hl[1,13] *}

  // Release any underlying resources, including the interface object.
  //
  // WARNING: The destructor of this class is marked as protected to disallow
  // clients from directly destroying this object since it may manage its own
  // lifetime through ref counting. Thus clients MUST call Release() in order to
  // destroy an instance of this class.
  virtual void Release() = 0;

  // Creates an operation builder and ties it to this context.

        ArtifactSpec b = a.addDependency("b", "[1.0,3.0]");

        ArtifactSpec managedB = createArtifactSpec("b", "5.0");

        ArtifactResolutionResult res = collect(a, managedB.artifact);
        assertEquals(
                createSet(new Object[] {a.artifact, managedB.artifact}), res.getArtifacts(), "Check artifact list");

import org.eclipse.aether.resolution.ArtifactDescriptorRequest;
import org.eclipse.aether.resolution.ArtifactRequest;
import org.eclipse.aether.resolution.DependencyRequest;

/**
 * Helper class to manage {@link RequestTrace} for better error logging.
 *
 * @since 3.9.9
 * @deprecated since 4.0.0, use {@code maven-api-impl} jar instead
 */
@Deprecated(since = "4.0.0")
public final class RequestTraceHelper {

Und **Ihre Benutzer** definieren auf irgendeine Weise (zum Beispiel irgendwo in einem Web-<abbr title="Benutzeroberfläche für das Visualisieren und Managen von Daten">Dashboard</abbr>) die **URL**, an die Ihre App diese Requests senden soll.

	// ttl for a cached value.
	ttl time.Duration

	opts Opts

	// Once can be used to initialize values for lazy initialization.
	// Should be set before calling Get().
	Once sync.Once

	// Managed values.
	val          atomic.Pointer[T]
	lastUpdateMs atomic.Int64
	updating     sync.Mutex
}

// New allocates a new cached value instance. Tt must be initialized with
// `.TnitOnce`.

import org.eclipse.aether.internal.impl.scope.ScopeDependencySelector;
import org.eclipse.aether.internal.impl.scope.ScopeManagerImpl;
import org.eclipse.aether.repository.LocalRepository;
import org.eclipse.aether.util.graph.manager.ClassicDependencyManager;
import org.eclipse.aether.util.graph.selector.AndDependencySelector;
import org.eclipse.aether.util.graph.selector.ExclusionDependencySelector;

import org.codehaus.plexus.classworlds.realm.DuplicateRealmException;
import org.eclipse.aether.artifact.Artifact;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Manages the class realms used by Maven. <strong>Warning:</strong> This is an internal utility class that is only
 * public for technical reasons, it is not part of the public API. In particular, this class can be changed or deleted

</div>

////

The only new option here is `--workers` telling Uvicorn to start 4 worker processes.

You can also see that it shows the **PID** of each process, `27365` for the parent process (this is the **process manager**) and one for each worker process: `27368`, `27369`, `27370`, and `27367`.

## Deployment Concepts { #deployment-concepts }