{* ../../docs_src/pydantic_v1_in_v2/tutorial004_an_py310.py hl[4,18] *}

### Migrate in steps { #migrate-in-steps }

/// tip

First try with `bump-pydantic`, if your tests pass and that works, then you're done in one command. ✨

///

		if len(remainCaches) > metacacheMaxEntries {
			// Sort oldest last...
			sort.Slice(remainCaches, func(i, j int) bool {
				return remainCaches[i].lastHandout.Before(remainCaches[j].lastHandout)
			})
			// Keep first metacacheMaxEntries...
			for _, cache := range remainCaches[metacacheMaxEntries:] {
				if time.Since(cache.lastHandout) > metacacheMaxClientWait {
					remove[cache.id] = struct{}{}
				}
			}
		}
	}

        // Test multiple calls with different configurations
        Map<String, Object> params = new HashMap<>();
        params.put("param", "value");

        // First call with model name
        ComponentUtil.setFessConfig(new FessConfig.SimpleImpl() {
            @Override
            public String getLtrModelName() {
                return "model1";
            }

            session.acquire();
        }

        // When - Multiple threads try to release/acquire concurrently
        for (int t = 0; t < threadCount; t++) {
            final boolean shouldRelease = (t < 3); // First 3 threads release, others acquire

            executor.submit(() -> {
                try {
                    startLatch.await();

                    if (shouldRelease) {

  private static final class NoInterface {}

  private abstract static class Implementation<K, V> implements Iterable<V>, Map<K, V> {}

  private abstract static class First<T> {}

  private abstract static class Second<D> extends First<D> {}

  private abstract static class Third<T, D> extends Second<T> {}

  private abstract static class Fourth<T, D> extends Third<D, T> {}

 * `IOException` and responding appropriately.
 *
 * @constructor Create a cache which will reside in [directory]. This cache is lazily initialized on
 *     first access and will be created if it does not exist.
 * @param directory a writable directory.
 * @param valueCount the number of values per cache entry. Must be positive.

 *
 * Comment lines are either blank or start with a `#` character. Lines may also end with a comment.
 * All comments are ignored.
 *
 * Regular lines contain fields separated by semicolons.
 *
 * The first element on each line is a single hex code point (like 0041) or a hex code point range
 * (like 0030..0039).
 *
 * The second element on each line is a mapping type, like `valid` or `mapped`.
 *

  public void runTest() throws Exception {
    /*
     * Note that we do not run this test under Android at the moment. For Android testing, see
     * AggregateFutureStateDefaultAtomicHelperTest.
     */

    // First, ensure that our classloaders are initializing the correct helper versions:

    checkHelperVersion(getClass().getClassLoader(), "SafeAtomicHelper");
    checkHelperVersion(NO_ATOMIC_FIELD_UPDATER, "SynchronizedAtomicHelper");

            DirectoryLeaseManager dirManager = getDirectoryLeaseManager(th);

            if (dirManager != null && smbFile.getContext().getConfig().isUseDirectoryLeasing()) {
                // Check parent directory cache first
                String parentPath = smbFile.getParent();
                if (parentPath != null) {
                    var parentCache = dirManager.getCacheEntry(parentPath);

## Using `BackgroundTasks` { #using-backgroundtasks }

First, import `BackgroundTasks` and define a parameter in your *path operation function* with a type declaration of `BackgroundTasks`:

{* ../../docs_src/background_tasks/tutorial001_py310.py hl[1,13] *}