Fisher–yates Shuffle basic idea (Knuth Shuffle):
To shuffle A of n elements (indices 0..n-1):For i-n−1 downto 1 DoJ←random integer with 0≤j≤iExchange A[j] and A[i]
JDK source code is as follows:
Copy Code code as follows:
/**
* Moves
Tuning OverviewMost spark job performance is mainly consumed in the shuffle link, because this link contains a lot of disk IO, serialization, network data transmission and other operations. Therefore, if you want to make the performance of the job
Tuning OverviewMost spark job performance is mainly consumed in the shuffle link, because this link contains a lot of disk IO, serialization, network data transmission and other operations. Therefore, if you want to make the performance of the job
php function Shuffle () takes an array of several random elements of the method analysis, shuffle array
This paper describes the PHP function shuffle () to take the array of random elements of a method. Share to everyone for your reference, as
Shuffle describes the process of data from the map task output to the reduce task input.Personal Understanding:The results of map execution are saved as a local file:As long as map execution is complete, the in-memory map data will be saved to the
This paper describes the PHP function shuffle () to take the array of random elements of a method. Share to everyone for your reference, as follows:
Sometimes we need to take a number of random elements in the array (such as random recommendations),
Shuffle () defines and uses the shuffle () function to rearrange the elements in the array in random order. Returns TRUE if successful, otherwise FALSE is returned. Note: This function assigns the new key name to the cells in the array. This will
Shuffle () defines and uses the shuffle () function to rearrange the elements in the array in random order. Returns TRUE if successful, otherwise FALSE is returned. Note: This function assigns the new key name to the cells in the array. This will
The shuffle () function of PHP analyzes several random elements in the array and shuffle the array. The shuffle () function of PHP analyzes several random elements in an array. This document describes how to shuffle () function of PHP to obtain
Mapreduce: Describes the shuffle process]
Blog type:
Mapreduce
Mapreduceiteye multi-thread hadoop Data Structure
The shuffle process is the core of mapreduce, also known as a miracle. To understand mapreduce, shuffle must be understood. I have
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