WebDriverWait.until() gets hung, don't know why

[Nick Klauer]

I'm using WebDriverWait to check for the presence of some elements (namely <iframes>) and it seems that it gets hung up and won't return at all. I could be using the class wrong, so I've attached the little bit of code that I've used to construct the waiting for element:

    public static List<WebElement> iframeTags(WebDriver driver) {

        return new WebDriverWait(driver, 30, 1000).until(new Function<WebDriver, List<WebElement>>() {

            public List<WebElement> apply(WebDriver driver) {

                return driver.findElements(By.tagName("iframe"));

            }

        });

    }

    ...

    final By iframe = By.tagName("iframe");

    List<WebElement> eles = iframeTags(driver);

Now, I'm trying to make sense of whether the timeout would occur at all, since I have never seen it actually throw an exception after a period of time.  It either works, or sits there and waits until the End of Days.  What am I doing wrong, or what could I be missing that would let this test work more consistently? 

[Daniel Wagner-Hall]

That code should always return immediately - WebDriverWait waits until
what is returned doesn't throw a NotFoundException, and doesn't
evaluate to false (where null evaluates to false). findElements will
return an empty List<WebElement> if none are present, and an empty
list isn't null. You may want to try implementing your own Wait class
modelled on https://code.google.com/p/selenium/source/browse/trunk/java/client/src/org/openqa/selenium/support/ui/WebDriverWait.java
which has empty-list logic, rather than null logic...

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[Nick Klauer]

So if what you say is true:

WebDriverWait waits until what is returned doesn't throw a NotFoundException, and doesn't evaluate to false (where null evaluates to false).

then why would it hang at all?  I can check for an empty list if it returns, and I have gotten empty lists back before.  What I'm confused about is why it would not return at all, even after the timeout.  Does the WebDriverWait(driver, <seconds>, <sleepMillis>) not throw an exception after <seconds> passes?  Does it not return at all, even if the time passes?

[Daniel Wagner-Hall]

Sounds like some other issue - if you execute the findElements not
wrapped in the wait, can you make it hang?