what's difference between emitted and transferred?

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Jimmy Jim

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Feb 17, 2012, 2:14:54 AM2/17/12

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On the Storm UI,some time ,the transferred num is not == emitted num.
So,what's the difference between them?

Nathan Marz

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Feb 17, 2012, 3:44:44 AM2/17/12

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Emitted is the number of times one of the "emit" methods is called on the OutputCollector. Transferred is the number of actual tuples sent to other tasks. For example, if bolt B has 5 tasks and subscribes to bolt A using an "all" grouping, "transferred" will be 5x "emitted" for that stream of bolt A. Similarly, if bolt A emits a stream that no one subscribes to, "transferred" will be 0.

On Thu, Feb 16, 2012 at 11:14 PM, Jimmy Jim <flyic...@gmail.com> wrote:

On the Storm UI,some time ,the transferred num is not == emitted num.
So,what's the difference between them?