The problem here I think is that as soon as the queue gets empty it hits the undefined entries. But after that, new entries are being pushed into the queue but get ignored because the threads were joined already at that time.

Okay. So now we get to the crux of the real question you should have asked: How to determine when there are no more directories to be processed? (And thus, the threads can safely terminate.)

You cannot have the main thread post the undefs once it has finished the initial population of the queue, because the worker threads will be adding to the queue as they process that initial population.

And you cannot use the absence of queue entries (Q->pending == 0), because another thread may add another directory to the queue a millisecond later.

This is the classic chicken & egg scenario. How can any of the worker threads know when they are finished, when at any given moment in time one of the other worker threads might queue an new directory to be processed?

I don't have an answer for you yet. I'm not sure that there is an answer given the current methodology of your code.

I'm sure that there is a better way, and I'll get back to you once I think of it.

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In reply to Re^7: Proper undefine queue with multithreads by BrowserUk
in thread Proper undefine queue with multithreads by sanc

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