Driver A Spark driver (aka an application’s driver process) is a JVM process that hosts SparkContext for a Spark application. It is the master node in a Spark application. It splits a Spark application into tasks and schedules them to run on executors. A driver is where the task scheduler lives and spawns tasks across workers. A driver coordinates workers and overall execution of tasks. It hosts Web UI for the environment.

当对一个数取模时，可以等价 a%b=a-a/b*b 1 2 println(-10%3)//-10%3=(-10)-(-3)*3=-10+9=-1 println(-10%-3)//-10%-3=(-10)-(3)*-3=-10+9=-1 在 scala 中支持代码块，返回值 1 2 3 val res = { if (num > 1) "ok" else 100 } Scala 不支持三目运算符 , 在 Scala 中使用 if – else 的方式实现 1 val

Network Interfaces Network interfaces represent a point of connection between a computer and a network. interfaces can be software or hardware /proc filesystem /proc/net/[tcp|udp|raw] /proc/net/route /proc/net/dev /proc/net/arp /proc/net/snmp /proc/sys/net which concerns various networking topics /proc/sys/net/core/ message_burst, message_cost message_burst defaults to 10 and message_cost defaults to 5. This means the kernel is limited to logging 10 entries every 5 seconds. netdev_max_backlog maximum number of packets allowed to queue on a particular interface.

MAC Media access control (MAC) addresses are identifiers uniquely assigned to network interfaces. first 3 octets refer to the Organizationally Unique Identifier (OUI) which can help identify manufacturers IP IP addresses are means of identifying devices connected to a network under Internet Protocol. In IPv4 we can partition a block of addresses into a subnet. The number that comes after the slash (/) is the subnet mask. This represents how many bits are in the network address, the remaining bits identify a host within the network.

Clone your fork: 1 git clone git@github.com:YOUR-USERNAME/YOUR-FORKED-REPO.git Add remote from original repository in your forked repository: 1 2 3 cd into/cloned/fork-repo git remote add upstream git://github.com/ORIGINAL-DEV-USERNAME/REPO-YOU-FORKED-FROM.git git fetch upstream Updating your fork from original repo to keep up with their changes: 1 git pull upstream master

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