In this tutorial, we will show you how to use Neocortix Cloud Services Scalable Compute to run a distributed batch job using JavaScript and node.js.
First, please follow the steps in the tutorial Setting Up For Batch Jobs.
After completion of the initial setup, you will have a directory with examples,
~/ncsexamples
.
In the subdirectory 
It will command the instances to receive the JavaScript file The output is a text file These output files will be sent back to the master host, and the master will then terminate the instances.
~/ncsexamples/batchMode
you will find the runBatchJavascript.py command.
This script will create a set of instances running on mobile devices, one instance for each frame to be computed (5 in
the default example provided).
startFrame = 1,
endFrame = 5,
helloFrame.js
, then
run it:
workerScriptPath = 'helloFrame.js'
def frameCmd( self, frameNum ):
jsFileName = os.path.basename( self.workerScriptPath )
cmd = 'node %s %d > %s' % \
(jsFileName, frameNum, self.frameOutFileName(frameNum))
return cmd
frame_<n>.out
containing
"Hello World! From frameNum = n"
Example Command
Simply run
When the program is done, the output files Each file will contain the text output
python3 ./runBatchJavascript.py
frame_<n>.out
will be put in a directory
./data/java_<datestamp>
Hello World! From frameNum = n
.
Substituting Your Own JavaScript file
With this simple framework, you can easily substitute your own JavaScript file to process the frames of the Batch job.
Just edit the
runBatchJavascript.py
file to change the workerScriptPath
to replace
helloFrame.js
with the name of your JavaScript file yourFile.js
, which
runs on an instance and processes a single frame. You may need to install different dependencies in the installerCmd
line.
Pro Tip: When you are experimenting with getting your code running on a Neocortix Scalable Compute instance, it may be easiest to spin up a single instance and get it installed and running there, before running it at scale as a part of a Batch job.