Asynchronous Apex in Salesforce

🚀 Asynchronous Apex in Salesforce

Asynchronous Apex is used for long-running, resource-intensive, or bulk operations that can't run within the standard synchronous limits. Salesforce provides several async mechanisms to meet different needs.

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📌 Why Use Async Apex?

• ✅ Handle large volumes of data
• ✅ Avoid governor limits
• ✅ Perform non-blocking tasks (e.g., callouts)
• ✅ Execute scheduled tasks

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1️⃣ Batch Apex

Used to process millions of records in manageable chunks asynchronously.

Key Methods:

• start() – Returns a query locator or iterable
• execute() – Processes each batch
• finish() – Final logic (e.g., email notifications)

Example: Batch Apex

global class AccountBatch implements Database.Batchable<sObject> {
    global Database.QueryLocator start(Database.BatchableContext bc) {
        return Database.getQueryLocator('SELECT Id, Name FROM Account');
    }

    global void execute(Database.BatchableContext bc, List<Account> scope) {
        for (Account acc : scope) {
            acc.Name += ' - Updated';
        }
        update scope;
    }

    global void finish(Database.BatchableContext bc) {
        System.debug('Batch Job Finished');
    }
}
  

🧪 To Run:

AccountBatch ab = new AccountBatch();
Database.executeBatch(ab, 200);

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2️⃣ Queueable Apex

Queueable Apex is like a lightweight batch that allows chaining jobs and supports complex logic and callouts.

Example: Queueable Apex

public class UpdateContactQueue implements Queueable {
    public void execute(QueueableContext context) {
        List<Contact> contacts = [SELECT Id, Email FROM Contact WHERE Email != null];
        for (Contact c : contacts) {
            c.Email = c.Email.toLowerCase();
        }
        update contacts;
    }
}
  

🧪 To Enqueue:

System.enqueueJob(new UpdateContactQueue());

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3️⃣ Scheduled Apex

Use Scheduled Apex to run logic at specific times or intervals.

Steps:

• Implement Schedulable interface
• Deploy or schedule via UI or code

Example: Scheduled Apex

public class MonthlyJob implements Schedulable {
    public void execute(SchedulableContext sc) {
        System.debug('Running monthly job!');
    }
}
  

🧪 To Schedule:

String cronExp = '0 0 8 1 * ?'; // 8 AM on 1st of every month
System.schedule('Monthly Job', cronExp, new MonthlyJob());

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4️⃣ Future Methods

Future methods are simple ways to run async logic. Best for quick, non-blocking operations like callouts or updates.

Rules:

• Must be @future
• Only supports primitive types and collections as parameters
• Can’t return values
• Limited governor scope

Example: Future Method

public class EmailUtils {
    @future
    public static void sendWelcomeEmail(String email) {
        System.debug('Sending email to: ' + email);
        // Logic to send email (mocked)
    }
}
  

🧪 To Call:

EmailUtils.sendWelcomeEmail('test@example.com');

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📊 Comparison Table

Feature	Batch Apex	Queueable	Scheduled	Future
Use Case	Large data sets	Chained logic, callouts	Timed jobs	Quick async tasks
Supports Chaining	❌ (Only via finish)	✅	✅	❌
Supports Callouts	✅ (Must implement Database.AllowsCallouts)	✅	✅	✅
Execution Timing	As triggered	As triggered	By schedule	As triggered

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✅ Best Practices

• Use Batch Apex for data volumes > 10,000
• Use Queueable Apex for flexible async logic and chaining
• Use Scheduled Apex for recurring tasks
• Use Future methods for simple, fire-and-forget jobs