Using Electron and Node.js to write a simple user interface to a process that generates data, and then allows the user to call gnuplot to show the data. Here is the code in main.js that calls gnuplot (gnuplot5-qt).

var menu = Menu.buildFromTemplate([
  {
      label: 'Run Graph',
      click() {
        commandLine()
      }
  },
// Other code
function commandLine () {
    var child = require('child_process').execFile;
    var executablePath = "/usr/bin/gnuplot";
    var parameters = ["-p","-e","filename='/home/prog1/PP_Logs/log1.txt'","/home/prog1/plot_log.p"];

    child(executablePath, parameters, function(err, data) {
      console.log(err);
      console.log(data.toString());
    });

gnuplot always opens, sometimes it stays open and I can exit it normally, but randomly it will close immediately after opening and prints the following error:

{ Error: Command failed: /usr/bin/gnuplot -p -e filename='/home/prog1/PP_Logs/log1.txt' /home/prog1/plot_log.p

at ChildProcess.exithandler (child_process.js:282:12)
at emitTwo (events.js:125:13)
at ChildProcess.emit (events.js:213:7)
at maybeClose (internal/child_process.js:921:16)
at Socket.stream.socket.on (internal/child_process.js:348:11)
at emitOne (events.js:115:13)
at Socket.emit (events.js:210:7)
at Pipe._handle.close [as _onclose] (net.js:549:12)
killed: false,
code: null,
signal: 'SIGSEGV',
cmd: '/usr/bin/gnuplot -p -e filename=\'/home/prog1/PP_Logs/log1.txt\' /home/prog1/plot_log.p' }

This same code works without issue if gimp is launched instead of gnuplot:

 var executablePath = "/usr/bin/gimp";
 var parameters = ["-s","/home/geenweb/Pictures/lgcm110.jpg"];

Given the SIGSEGV, I’m assuming that gnuplot is running out of memory when it crashes. Is there some way to allocate more memory? Is there a better way to call gnuplot? I’m just learning Electron, Node.js, and javascript. Thanks for your help.

Solution:

Firstly, you should make sure you’re running the current LTS version of Node, which at the time of this writing is v8.9.4.

ChildProcess.execFile() runs your command in a new process by default which might be the cause of your error. You may wish to specify that your command be run in a newly spawned shell by setting the shell flag in the options you pass to execFile() to either true which will cause the default /bin/sh shell to be used or to a path to the shell you wish to use.

Running your process in a /bin/sh or /bin/bash shell will give you access to the shell ulimit built-in command which will provide you a means to modify resource limits for the shell. See Setting Limits With ulimit for information about the ulimit command and how to use it.

If this is the case, you’ll need to wrap your command invocation in a shell-script that first runs ulimit with the correct limits.

See Limit Memory Usage For A Single Linux Process for further discussion on this topic.

Your problem might also be caused by the default allocated size of the buffers used to transfer the running command’s output via stdout and stderr.

If this is the case and the program’s output exceeds 200*1024 bytes, you can use the maxBuffer in the options you pass to execFile() to increase the size of these buffers.