Some, such as `http2client` and `http2server`,
will be maintained much longer, even indefinitely.

When possible, each GODEBUG setting has an associated
[runtime/metrics](/pkg/runtime/metrics/) counter
named `/godebug/non-default-behavior/<name>:events`
that counts the number of times a particular program's
behavior has changed based on a non-default value
for that setting.
For example, when `GODEBUG=http2client=0` is set,

// GetLock tries to get a write lock on dm before the timeout elapses.
//
// If the lock is already in use, the calling go routine
// blocks until either the mutex becomes available and return success or
// more time has passed than the timeout value and return false.
func (dm *DRWMutex) GetLock(ctx context.Context, cancel context.CancelFunc, id, source string, opts Options) (locked bool) {
	isReadLock := false

     * <p>
     * Specifically, if the SID has
     * been resolved and it is not a domain SID or builtin account,
     * the full DOMAIN\name form of the account will be
     * returned (e.g. MYDOM\alice or MYDOM\Domain Users).
     * If the SID has been resolved but it is is a domain SID,
     * only the domain name will be returned (e.g. MYDOM).
     * If the SID has been resolved but it is a builtin account,

    MinMaxPriorityQueue<Integer> mmHeap = MinMaxPriorityQueue.create();
    mmHeap.addAll(Lists.newArrayList(1, 2));
    Iterator<Integer> it = mmHeap.iterator();
    assertTrue("Iterator has reached end prematurely", it.hasNext());
    it.next();
    it.next();
    assertThrows(NoSuchElementException.class, () -> it.next());
  }

  public void testIteratorConcurrentModification() {

// no holes in it). On the other hand, the zero value of sparseDatas implies
// that the file has no data in it, which is rather odd.
//
// As an example, if the underlying raw file contains the 10-byte data:
//
//	var compactFile = "abcdefgh"
//
// And the sparse map has the following entries:
//
//	var spd sparseDatas = []sparseEntry{
//		{Offset: 2,  Length: 5},  // Data fragment for 2..6

   * linefeed ({@code "\r\n"}).
   *
   * @return a {@code String} containing the contents of the line, not including any
   *     line-termination characters, or {@code null} if the end of the stream has been reached.
   * @throws IOException if an I/O error occurs
   */
  @CanIgnoreReturnValue // to skip a line
  @CheckForNull
  public String readLine() throws IOException {
    while (lines.peek() == null) {

            if (propValue.startsWith("!")) {
                reverseValue = true;
                propValue = propValue.substring(1);
            }

            // we have a value, so it has to match the system value...
            return reverseValue != propValue.equals(sysValue);
        } else {
            return reverseName != (sysValue != null && !sysValue.isEmpty());
        }
    }

    @Override

     */
    @Nonnull
    Model getEffectiveModel();

    /**
     * Gets the profiles that were active during model building.
     *
     * @return The active profiles of the model or an empty list if the model has no active profiles.
     */
    @Nonnull
    List<Profile> getActivePomProfiles();

    /**
     * Gets the external profiles that were active during model building. External profiles are those that were

var ErrAlreadyLocked = errors.New("file already locked")

// RLockedFile represents a read locked file, implements a special
// closer which only closes the associated *os.File when the ref count.
// has reached zero, i.e when all the readers have given up their locks.
type RLockedFile struct {
	*LockedFile
	mutex sync.Mutex
	refs  int // Holds read lock refs.
}

      description: Tell us what should happen
    validations:
      required: true
  - type: textarea
    id: context
    attributes:
      label: Context (optional)
      description: |
        How has this issue affected you? What are you trying to accomplish?
        Providing context helps us come up with a solution that is most useful in the real world
    validations:
      required: false
  - type: textarea