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Apache Hadoop 2.7.5 Release Notes

These release notes cover new developer and user-facing incompatibilities, important issues, features, and major improvements.

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• HDFS-8829 | Major | Make SO_RCVBUF and SO_SNDBUF size configurable for DataTransferProtocol sockets and allow configuring auto-tuning

HDFS-8829 introduces two new configuration settings: dfs.datanode.transfer.socket.send.buffer.size and dfs.datanode.transfer.socket.recv.buffer.size. These settings can be used to control the socket send buffer and receive buffer sizes respectively on the DataNode for client-DataNode and DataNode-DataNode connections. The default values of both settings are 128KB for backwards compatibility. For optimum performance it is recommended to set these values to zero to enable the OS networking stack to auto-tune buffer sizes.

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• YARN-6959 | Major | RM may allocate wrong AM Container for new attempt

ResourceManager will now record ResourceRequests from different attempts into different objects.