A broadcast variable. Broadcast variables allow the programmer to keep a read-only variable
cached on each machine rather than shipping a copy of it with tasks. They can be used, for
example, to give every node a copy of a large input dataset in an efficient manner. Spark also
attempts to distribute broadcast variables using efficient broadcast algorithms to reduce
communication cost.
Broadcast variables are created from a variable v by calling SparkContext#broadcast.
The broadcast variable is a wrapper around v, and its value can be accessed by calling the
value method. The interpreter session below shows this:
After the broadcast variable is created, it should be used instead of the value v in any
functions run on the cluster so that v is not shipped to the nodes more than once.
In addition, the object v should not be modified after it is broadcast in order to ensure
that all nodes get the same value of the broadcast variable (e.g. if the variable is shipped
to a new node later).
T
Type of the data contained in the broadcast variable.
A broadcast variable. Broadcast variables allow the programmer to keep a read-only variable cached on each machine rather than shipping a copy of it with tasks. They can be used, for example, to give every node a copy of a large input dataset in an efficient manner. Spark also attempts to distribute broadcast variables using efficient broadcast algorithms to reduce communication cost.
Broadcast variables are created from a variable
vby calling SparkContext#broadcast. The broadcast variable is a wrapper aroundv, and its value can be accessed by calling thevaluemethod. The interpreter session below shows this:After the broadcast variable is created, it should be used instead of the value
vin any functions run on the cluster so thatvis not shipped to the nodes more than once. In addition, the objectvshould not be modified after it is broadcast in order to ensure that all nodes get the same value of the broadcast variable (e.g. if the variable is shipped to a new node later).Type of the data contained in the broadcast variable.