THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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然后就要想办法，让预测执行的execution所处理的inputSplit跟原execution要一样，这样才能保证包含source operator的region能支持预测执行。
这里要画一张图。
Based on FLINK-10205, we could ensure ....
Manage middle ResultPartition
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