Github user hequn8128 commented on the issue: https://github.com/apache/flink/pull/6335 Hi @zhangminglei , Good catch! Maybe the Reader may also need to be adapted, making `new InputStreamReader` to `Channels.newReader`. I find a benchmark about File InputStream and Reader [here](https://arnaudroger.github.io/blog/2017/03/20/faster-reader-inpustream-in-java.html). Hope it helps.
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