Собственно код:

private readonly TimeSpan _defaultTimeout = TimeSpan.FromSeconds(5); // default timeout
private readonly ReaderWriterLockSlim _rwLock = new ReaderWriterLockSlim();

....

public async Task DoSomethingAsync()
{
    ....     
    
    if (this._rwLock.TryEnterWriteLock(this._defaultTimeout)) {
        try {
            ...
            await this.DoSomeOtherTaskAsync();
            ...
        finally {
             this._rwLock.ExitWriteLock();
        }
     }
}

Вопрос, почему периодически this._rwLock.ExitWriteLock(); падает с

System.Threading.SynchronizationLockException: The write lock is being released without being held.
at System.Threading.ReaderWriterLockSlim.ExitWriteLock()

других Exception в этот момент не замечено.