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Programmatically handle long running tasks in Apps Script

An approach to process hundreds of thousands of rows of data (say, on Google Sheets) without running into the script execution timeout error.

Sourabh Choraria

Feb 10, 2023 • 7 min read

Photo by Icons8 Team / Unsplash

TL;DR — the typical challenge we face with tasks that take longer to execute is that of running into the execution timeout error (that's at 6 minutes — Script runtime — as of 10-Feb-2023) and this article merely elaborates on how to bypass script execution timeout *with a detailed example*.

Prerequisite

You must already have a starter function that works for a relatively smaller set of rows, that you wish to scale to 100s if not 1000s or even 10s-of-1000s of rows.

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Step 0. Starting point — example function to get registrar data for each domain.

If you want to follow along, you can make a copy of this spreadsheet and replace the Apps Script code as below —

function getDomainInfo() {
  const ss = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  const [header, ...values] = ss.getDataRange().getValues();
  const domainIndex = header.indexOf("domain");
  const registrarIndex = header.indexOf("registrar");
  const totalValues = values.length;
  for (let i = 0; i < totalValues; i++) {
    const row = values[i];
    const name = row[domainIndex];
    const url = `https://rdap.verisign.com/com/v1/domain/${name}`;
    const response = UrlFetchApp.fetch(url, { muteHttpExceptions: true });
    if (response.getResponseCode() === 200) {
      const rowData = [];
      const data = JSON.parse(response.getContentText());
      const registrar = data.entities[0].vcardArray[1][1][3];
      const createdDate = data.events[0].eventDate.replace("T", " ").replace("Z", "");
      const expiryDate = data.events[1].eventDate.replace("T", " ").replace("Z", "");
      rowData.push([registrar, createdDate, expiryDate]);
      ss.getRange((i + 1) + 1, registrarIndex + 1, 1, 3).setValues(rowData);
      SpreadsheetApp.flush();
    }
  }
}

Approach

Step 1

Task: Let's start by adding a status column on the spreadsheet and also modify the script code to update status whenever it starts & ends processing each of the rows
Explanation: This will allow us to monitor and track which rows have already been processed and should the script run again, it could automatically detect the row from which it needs to start (as opposed to re-doing everything from the beginning)
Modification preview —

Code snippet —

function getDomainInfo() {
  const ss = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  const [header, ...values] = ss.getDataRange().getValues();
  const domainIndex = header.indexOf("domain");
  const registrarIndex = header.indexOf("registrar");
  const statusIndex = header.indexOf("status");
  const totalValues = values.length;
  for (let i = 0; i < totalValues; i++) {
    const row = values[i];
    const status = row[statusIndex];
    if (status !== 'DONE') {
      ss.getRange((i + 1) + 1, statusIndex + 1).setValue("Processing...");
      SpreadsheetApp.flush();
      const name = row[domainIndex];
      const url = `https://rdap.verisign.com/com/v1/domain/${name}`;
      const response = UrlFetchApp.fetch(url, { muteHttpExceptions: true });
      if (response.getResponseCode() === 200) {
        const rowData = [];
        const data = JSON.parse(response.getContentText());
        const registrar = data.entities[0].vcardArray[1][1][3];
        const createdDate = data.events[0].eventDate.replace("T", " ").replace("Z", "");
        const expiryDate = data.events[1].eventDate.replace("T", " ").replace("Z", "");
        rowData.push([registrar, createdDate, expiryDate]);
        ss.getRange((i + 1) + 1, registrarIndex + 1, 1, 3).setValues(rowData);
        ss.getRange((i + 1) + 1, statusIndex + 1).setValue("DONE");
        SpreadsheetApp.flush();
      }
    }
  }
}

Step 1. Add 'status' column to the sheet and modify the code to update the same.

Workflow overview —

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Step 1. Add 'status' column to the sheet and modify the code to update the same.

Step 2

Task: Create a new function — isTimeUp — and modify the script to check if we have enough time to run through another loop and get data for the next row.
Explanation: This would allow us to set a custom timeout of our own and that would avoid the script to stop abruptly by not allowing it to hit its default runtime limit.
Modification preview —

Code snippet —

function getDomainInfo() {
  const ss = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  const [header, ...values] = ss.getDataRange().getValues();
  const domainIndex = header.indexOf("domain");
  const registrarIndex = header.indexOf("registrar");
  const statusIndex = header.indexOf("status");
  const totalValues = values.length;
  const startTime = new Date();
  for (let i = 0; i < totalValues; i++) {
    if (isTimeUp(startTime)) {
      break;
    } else {
      const row = values[i];
      const status = row[statusIndex];
      if (status !== 'DONE') {
        ss.getRange((i + 1) + 1, statusIndex + 1).setValue("Processing...");
        SpreadsheetApp.flush();
        const name = row[domainIndex];
        const url = `https://rdap.verisign.com/com/v1/domain/${name}`;
        const response = UrlFetchApp.fetch(url, { muteHttpExceptions: true });
        if (response.getResponseCode() === 200) {
          const rowData = [];
          const data = JSON.parse(response.getContentText());
          const registrar = data.entities[0].vcardArray[1][1][3];
          const createdDate = data.events[0].eventDate.replace("T", " ").replace("Z", "");
          const expiryDate = data.events[1].eventDate.replace("T", " ").replace("Z", "");
          rowData.push([registrar, createdDate, expiryDate]);
          ss.getRange((i + 1) + 1, registrarIndex + 1, 1, 3).setValues(rowData);
          ss.getRange((i + 1) + 1, statusIndex + 1).setValue("DONE");
          SpreadsheetApp.flush();
        }
      }
    }
  }
}

const isTimeUp = (startTime) => new Date().getTime() - startTime.getTime() > 3000;

Step 2. Add "isTimeUp" function to set custom timeout & check time availability for next run.

Workflow overview —

0:00

Step 2. Add "isTimeUp" function to set custom timeout & check time availability for next run.

Step 3

Task: Set-up a time-based trigger that would run at a specific frequency
Explanation: In cases where the script exceeds the custom timeout limit, this would allow the script to re-run itself after a certain duration (in this case, every 1 minute) and that would seamlessly allow the next set of rows to be processed automatically
Modification preview —

Code snippet —

const documentProperties = PropertiesService.getDocumentProperties();

function getDomainInfo() {
  const ss = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  const [header, ...values] = ss.getDataRange().getValues();
  const domainIndex = header.indexOf("domain");
  const registrarIndex = header.indexOf("registrar");
  const statusIndex = header.indexOf("status");
  const totalValues = values.length;
  const startTime = new Date();
  const triggerId = documentProperties.getProperty("timeOutTriggerId");
  for (let i = 0; i < totalValues; i++) {
    if (isTimeUp(startTime)) {
      if (triggerId == null) {
        const trigger = ScriptApp.newTrigger("getDomainInfo")
          .timeBased()
          .everyMinutes(1)
          .create();
        documentProperties.setProperty("timeOutTriggerId", trigger.getUniqueId());
        break;
      }
    } else {
      const row = values[i];
      const status = row[statusIndex];
      if (status !== 'DONE') {
        ss.getRange((i + 1) + 1, statusIndex + 1).setValue("Processing...");
        SpreadsheetApp.flush();
        const name = row[domainIndex];
        const url = `https://rdap.verisign.com/com/v1/domain/${name}`;
        const response = UrlFetchApp.fetch(url, { muteHttpExceptions: true });
        if (response.getResponseCode() === 200) {
          const rowData = [];
          const data = JSON.parse(response.getContentText());
          const registrar = data.entities[0].vcardArray[1][1][3];
          const createdDate = data.events[0].eventDate.replace("T", " ").replace("Z", "");
          const expiryDate = data.events[1].eventDate.replace("T", " ").replace("Z", "");
          rowData.push([registrar, createdDate, expiryDate]);
          ss.getRange((i + 1) + 1, registrarIndex + 1, 1, 3).setValues(rowData);
          ss.getRange((i + 1) + 1, statusIndex + 1).setValue("DONE");
          SpreadsheetApp.flush();
        }
      }
    }
  }
}

const isTimeUp = (startTime) => new Date().getTime() - startTime.getTime() > 3000;

Step 3. Create time-based trigger to automatically run the function after set interval.

Note: We're also making use of a property store (in this case, getDocumentProperties as that would allow us to store the trigger once it has already been created after the first run (thus ensuring we don't create a new trigger every time the script runs) and because it would come in handy during the next/final step of our workflow.

Step 4

Task: Delete the time-based trigger created as part of Step 3.
Explanation: While this is an optional step, it is highly recommended NOT to be skipped because if unchecked, the time-based trigger would run indefinitely (even if it may have no rows to process), making the script and the document too resource intensive.
Modification preview —

Code snippet —

const documentProperties = PropertiesService.getDocumentProperties();

function getDomainInfo() {
  const ss = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  const [header, ...values] = ss.getDataRange().getValues();
  const domainIndex = header.indexOf("domain");
  const registrarIndex = header.indexOf("registrar");
  const statusIndex = header.indexOf("status");
  const totalValues = values.length;
  const startTime = new Date();
  const triggerId = documentProperties.getProperty("timeOutTriggerId");
  for (let i = 0; i < totalValues; i++) {
    if (isTimeUp(startTime)) {
      if (triggerId == null) {
        const trigger = ScriptApp.newTrigger("getDomainInfo")
          .timeBased()
          .everyMinutes(1)
          .create();
        documentProperties.setProperty("timeOutTriggerId", trigger.getUniqueId());
        break;
      }
    } else {
      const row = values[i];
      const status = row[statusIndex];
      if (status !== 'DONE') {
        ss.getRange((i + 1) + 1, statusIndex + 1).setValue("Processing...");
        SpreadsheetApp.flush();
        const name = row[domainIndex];
        const url = `https://rdap.verisign.com/com/v1/domain/${name}`;
        const response = UrlFetchApp.fetch(url, { muteHttpExceptions: true });
        if (response.getResponseCode() === 200) {
          const rowData = [];
          const data = JSON.parse(response.getContentText());
          const registrar = data.entities[0].vcardArray[1][1][3];
          const createdDate = data.events[0].eventDate.replace("T", " ").replace("Z", "");
          const expiryDate = data.events[1].eventDate.replace("T", " ").replace("Z", "");
          rowData.push([registrar, createdDate, expiryDate]);
          ss.getRange((i + 1) + 1, registrarIndex + 1, 1, 3).setValues(rowData);
          ss.getRange((i + 1) + 1, statusIndex + 1).setValue("DONE");
          SpreadsheetApp.flush();
        }
      }
      if (i === totalValues - 1) {
        if (triggerId !== null) {
          ScriptApp.deleteTrigger(
            ScriptApp.getProjectTriggers()
              .filter(trigger => trigger.getUniqueId() === triggerId)[0]
          );
          documentProperties.deleteProperty("timeOutTriggerId");
          break;
        }
      }
    }
  }
}

const isTimeUp = (startTime) => new Date().getTime() - startTime.getTime() > 3000;

Step 4. Delete the time-based trigger once all the rows have been processed.

Summary

Step 0: Create your workflow for a smaller dataset that would fit within the script runtime
Step 1: Add a status column to monitor & track the number of rows being processed and the ones to skip during subsequent runs
Step 2: Add a new function to set a custom timeout and check if we have enough time before processing the next set of data/row
Step 3: Create a time-based trigger to re-run the function after first-run automatically
Step 4: Delete the time-based trigger (created in the previous step) once all the data has been processed