InitProgram.r.yaml

label: PKGR09 - Use of initialisation program text
categories:
- Example
- R Language Example
- Package Example
description: |
  This example demonstrates use of the initialisation
  program text.

  The runtime server supports processing multiple requests
  through the same R runtime for efficiency. The runtime
  environment uses R environment objects to isolate each request
  and to avoid invocation of a program poluting other invocations.

  A program can specify an initialisation program text that will
  be run only once per R runtime. This can be used to load
  complex models into memory and avoid the overhead of having to
  load a model on each request. The initialisation program text
  is run within the context of a separate R environment, and this
  environment is then locked to prevent further modification.

  This example simply sets a variable in the initialisation text that
  is then referenced in the main program text.

  Note that the set up of the 'Demo' Environment object in the Hub
  is such that a new worker process is created for each request. Since
  a new worker process is created for each request, a new R runtime
  is created per request anyway, so the initialisation program is
  execute for each request. In order to properly see the effect of
  the one-time execution of the initialisation program it is necessary
  to set the `Idle Timeout` value on the `Default R Processing Engine`
  engine of the Demo Environment to a value other than 0.

  From the log it is possible to tell whether the initialisation
  program has been run or not.

resultFormat: json
resultObjectName: result
initProgramText: |
  a <- 42