}

  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.
  public void testWeakImplementations() {
    for (Striped<?> striped : weakImplementations()) {
      WeakReference<Object> weakRef = new WeakReference<>(striped.get(new Object()));
      GcFinalization.awaitClear(weakRef);
    }
  }

  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.

   * from GC, as with {@link #awaitClear}. Because there are no guarantees for the order of GC
   * finalization processing, there may still be some unfinished work for the GC to do after this
   * method returns.
   *
   * <p>This method does not create any memory pressure as would be required to cause soft
   * references to be processed.
   *

  // app (like the FrqUser class above), then the app's ClassLoader will never be gc'd. The reason
  // is that we attempt to run a thread in a separate ClassLoader that will detect when the FRQ
  // is no longer referenced, meaning that the app's ClassLoader has been gc'd, and when that
  // happens. But the thread's supposedly separate ClassLoader actually has a reference to the app's

    } catch (NoSuchElementException expected) {
    }
  }


  @J2ktIncompatible // weak references, details of GC
  @GwtIncompatible // weak references
  @AndroidIncompatible // depends on details of GC
  public void testFreesNextReference() {
    Iterator<Object> itr =
        new AbstractIterator<Object>() {
          @Override
          public Object computeNext() {

   * from GC, as with {@link #awaitClear}. Because there are no guarantees for the order of GC
   * finalization processing, there may still be some unfinished work for the GC to do after this
   * method returns.
   *
   * <p>This method does not create any memory pressure as would be required to cause soft
   * references to be processed.
   *

            return b.toString();
        }).collect(Collectors.joining(",")));
        buf.append("},");
        final GarbageCollectors gc = jvmStats.getGc();
        buf.append("\"gc\":{");
        buf.append(Arrays.stream(gc.getCollectors()).map(c -> {
            final StringBuilder b = new StringBuilder();
            b.append('"').append(StringEscapeUtils.escapeJson(c.getName())).append("\":{");

    // initialSize will most likely be 2, but it's possible for the GC to have already run, so we'll
    // observe a size of 1
    long initialSize = cache.size();
    assertTrue(initialSize == 1 || initialSize == 2);

    // wait up to 5s
    byte[] filler = new byte[1024];
    for (int i = 0; i < 500; i++) {
      System.gc();

      CacheTesting.drainReferenceQueues(cache);
      if (cache.size() == 1) {

  }

  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.
  public void testWeakImplementations() {
    for (Striped<?> striped : weakImplementations()) {
      WeakReference<Object> weakRef = new WeakReference<>(striped.get(new Object()));
      GcFinalization.awaitClear(weakRef);
    }
  }

  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.

import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link FinalizableReferenceQueue}.
 *
 * @author Bob Lee
 */
// - depends on details of GC and classloading
// - .class files aren't available
// - possibly no real concept of separate ClassLoaders?
@AndroidIncompatible
@GwtIncompatible
public class FinalizableReferenceQueueTest extends TestCase {

import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link FinalizableReferenceQueue}.
 *
 * @author Bob Lee
 */
// - depends on details of GC and classloading
// - .class files aren't available
// - possibly no real concept of separate ClassLoaders?
@AndroidIncompatible
@GwtIncompatible
public class FinalizableReferenceQueueTest extends TestCase {