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• --no.data.loss - to automatically apply all the necessary configurations in order to maker sure no data loss.
• --consumer.rebalance.listener - to allow user to wire in a custom rebalance listener which implements ConusmerRebalanceCallback interface. An internal rebalance listener which implements ConsumerRebalanceCallback is wired in by default to avoid duplicates on consumer rebalance. User could still specify a custom listener class in command line argument. The internal rebalance listener will call that custom listener after it finishes the default logic.
• --consumer.rebalance.listener.args - to provide arguments to custom rebalance listener constructor.
• --message.handler - to allow user do some simple process on the messages (e.g. filtering, reformatting, etc)
• --message.handler.args - to provide arguments
• --abortOnSendFail - define whether mirror maker should abort on when a send failed.

Proposed Changes

• Each mirror maker thread consume messages, process them and then send them.
• Scale by creating more mirror maker thread.

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• Mirror maker will only send one request to a broker at any given point.
• If any exception is caught in producer/consumer thread or OutOfMemory exception is caught in offset commit thread, mirror maker will try to commit the acked offsets then exit immediately.
• For RetriableException in producer, producer will retry indefinitely. If retry did not work, eventually the entire mirror maker will block on producer buffer full.
• For None-retriable exception, if --abortOnSendFail is specified, stop the mirror maker. Otherwise producer callback will record the message that was not successfully sent but let the mirror maker move on. In this case, that message will be lost in target cluster.

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