Improve chart update performance in GAS - performance

Question

I have a function that is updating every chart of a sheet and my main issue is that the updateChart() function is really slow (about 50 seconds) :
I already made a script that parallelize the function but due to the 20 triggers per script limitation I can only run my thread twice. So I wanted to know if there was anything that can speed up the update of my charts.
function ModifyVAxisChart()
{
var ss=SpreadsheetApp.getActiveSpreadsheet().getSheetByName("DCN Dashboard Data");
var rangeMax=ss.getRange("O3:O231").getValues();//Range to modify if you add charts
var rangeMinId=ss.getRange("P3:P232").getValues();//Range to modify if you add charts
var i=0;
var nbChart=39;
//Logger.log("range Max ="+rangeMax + "autre="+rangeMinId);
var Vmin=0;
var Vmax=0;
var id=-1;
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("DCN Dashboard");
var chart = sheet.getCharts();
for(i=0;i<nbChart;i++)
{
Vmax=rangeMax[i*6];
Vmin=rangeMinId[i*6];
id=rangeMinId[(i*6)+1];
var delta=(Vmax-Vmin)*0.1;
Logger.log("Vmax="+Vmax+"Vmin="+Vmin+"id="+id+"i="+i);
var currChart = chart[id];
if(currChart.getType()!="COLUMN")
{
Vmin-=delta
Vmax=Number(Vmax)+(delta*1.5)//Number() function to avoid Vmax becoming a string for no reason
}
Logger.log("Vmax="+Vmax+"Vmin="+Vmin+"id="+id+"i="+i);
currChart = currChart.modify()
.setOption('vAxes', {0: {textStyle: {fontSize: 10}, titleTextStyle: {fontSize : 8}, viewWindow: {min: Vmin, max:Vmax}}})//adpative vaxis for AREA and COMBO
.build();
sheet.updateChart(currChart);
}
}

Answer 1

As the App script functions aren't asynchronous, they will wait until the request is complete to keep running the code (and thus to run the rest of the requests). What you could do is to make the requests using the Sheets API [1] in either JavaScript (you would need to serve and html) or using the UrlFetchApp class [2], this way you could initiate the requests without needing to wait for the response from the previous request.
I implemented the fetchAll() method [2] with one request to update a chart and worked successfully, here is the code (you need to put the sheetID):
function uploadChart() {
var data = SpreadsheetApp.getActiveSpreadsheet();
var sheet = data.getSheets()[1];
var chart = sheet.getCharts()[0];
var chartId = chart.getChartId();
var token = ScriptApp.getOAuthToken();
var url = "https://sheets.googleapis.com/v4/spreadsheets/SHEET_ID:batchUpdate";
var chartBody = {
"updateChartSpec": {
"chartId": chartId,
"spec": {
"title": "Model Q1 Sales",
"basicChart": {
"chartType": "BAR",
"legendPosition": "RIGHT_LEGEND",
"axis": [
{
"format": {
"bold": true,
"italic": true,
"fontSize": 24
},
"position": "BOTTOM_AXIS",
"title": "Sales"
},
{
"format": {
"bold": true,
"italic": true,
"fontSize": 24
},
"position": "LEFT_AXIS",
"title": "Model Numbers"
}
],
"domains": [
{
"domain": {
"sourceRange": {
"sources": [
{
"startRowIndex": 0,
"endRowIndex": 6,
"startColumnIndex": 0,
"endColumnIndex": 1
}
]
}
}
}
],
"series": [
{
"series": {
"sourceRange": {
"sources": [
{
"startRowIndex": 0,
"endRowIndex": 6,
"startColumnIndex": 1,
"endColumnIndex": 2
}
]
}
},
"targetAxis": "BOTTOM_AXIS"
},
{
"series": {
"sourceRange": {
"sources": [
{
"startRowIndex": 0,
"endRowIndex": 6,
"startColumnIndex": 2,
"endColumnIndex": 3
}
]
}
},
"targetAxis": "BOTTOM_AXIS"
},
{
"series": {
"sourceRange": {
"sources": [
{
"startRowIndex": 0,
"endRowIndex": 6,
"startColumnIndex": 3,
"endColumnIndex": 4
}
]
}
},
"targetAxis": "BOTTOM_AXIS"
}
],
"headerCount": 1
}
}
}
}
var requestBody = {
'requests': [chartBody]
}
var request1 = {
'url': url,
'headers': {
'Authorization': 'Bearer ' + token,
},
'method' : 'post',
'contentType': 'application/json',
'payload' : JSON.stringify(requestBody),
'muteHttpExceptions': true
};
var requests = [request1]
var response = UrlFetchApp.fetchAll(requests);
Logger.log(response)
}
I used the update chart json from the "edit a chart" example [1].
To add more requests, you can either add more request jsons in the fetchAll() array parameter or add more update chart jsons in the 'requests' array on requestBody.
[1] https://developers.google.com/sheets/api/samples/charts
[2] https://developers.google.com/apps-script/reference/url-fetch/url-fetch-app#fetchAll(Object)