Why need to check the current thread not hold the lock on this in pollPage() of ExchangeClient?

[squallud]

hello all,

I noticed that there is a line of code in pollPage() of ExchangeClient that checking current thread not hold the monitor lock, could any one explain why this check is needed? Thank you.

public SerializedPage pollPage()
{
checkState(!Thread.holdsLock(this), "Can not get next page while holding a lock on this");
......
}