Concurrent Apex Limit - Unable to Process Request. Concurrent requests limit exceeded.

Please do continue to like, share and subscribe sfdconestop Youtube channel, if you find the Salesforce tutorials(100+ Video's) to be informative!!
▶️Subscribe:  https://www.youtube.com/c/sfdconestop
👉 https://sfdconestop.blogspot.com/
👀 Follow us on Linkedin : https://www.linkedin.com/company/sfdconestop

 

This is one of the Governor limit you may hit if you do not follow the best practices during implementation/code development. Below is the limit where for most of the orgs the limit is 10 which means you cannot have 10 synchronous transactions running concurrently for more than 5 second as for 11th request you hit the governor limit error  as below -



Governor limit:
Number of synchronous concurrent requests for long-running requests that last longer than 5 seconds for each organization.*

Error:
"Unable to Process Request. Concurrent requests limit exceeded.
To protect all customers from excessive usage and Denial of Service attacks, we limit the number of long-running requests that are processed at the same time by an organization. Your request has been denied because this limit has been exceeded by your organization. Please try your request again later."

https://help.salesforce.com/articleView?id=admin_web_limits.htm&type=5

What Counts Against the Limit

A single synchronous Apex request could include Apex code, SOQL, callouts, and triggers. You might need to tune these and other common components because the duration of their transactions counts toward the request limit.

Apex	Classes/controllers, triggers
SOQL
Web Services	External and Apex Web Services
Visualforce	ActionPoller, Ajax/ActionFunctions, JavaScript Remoting
API	Calls to an Apex Class

How to Design to Avoid the Limit

Take the concurrent request limit into consideration as you design your application around your business processes. Does the business process need to be synchronous? Is batch processing possible? Can you use the Streaming API?
Web Services

The most common causes of limit errors are synchronous Web service callouts. When one of your application’s users submits an order, that business process depends upon one or more external Web services, which must finish running for your application to actually create the order. If these external Web services cannot scale to your expected volumes, consider alternative solutions, such as using a callback instead of waiting for the callouts to complete.

To use a callback, just continue to make the synchronous callout. The following steps complete automatically after that.
The external Web service immediately returns an acknowledgement, saying that it received your request.
After the external Web service processing completes, it calls an Apex Web service to update the appropriate data.
The Streaming API publishes that updated data.


SOQL

The performance of your queries and DML operations is another big contributor to long-running requests. As your data grows, inefficient SOQL affects Visualforce pages, detail pages, list views and reports. If you’re querying for large amounts of data, you’ll incur additional processing time both when querying and rendering the data.

Refer to the Force.com Query Optimizer webinar for more information.
Data Skew

Data skew can also contribute to concurrent request limit errors. Consider the following scenario. You have a parent object with 10,000 or more child objects. Ordinarily, when you insert or change an owner of a child object, the Force.com platform automatically locks the parent for a certain amount of time. However, because you have data skew, the platform holds this lock even longer while determining the appropriate record access. The wait time for your lock is included in your total request time, and it causes your request to run for more than 5 seconds.

To avoid data skew so that you can also avoid ending up in this situation, read Reducing Lock Contention by Avoiding Data Skew.
Visualforce

With the ActionPoller component, you can poll by calling an Apex class. Unfortunately, you can’t dynamically change the polling interval or condition. This can result in a large number of unneeded requests. If the polling operation is expensive and takes longer than 5 seconds, you’ll quickly hit the limit. For more scalable requests, use the Streaming API, not polling, to subscribe to near real-time notifications of changes to data.

The <Apex:ActionFunction> component provides support for invoking controller action methods directly from JavaScript code using an AJAX request. JavaScript remoting extends this capability and allows you to create pages with complex, dynamic behavior that isn’t possible with the standard Visualforce AJAX components. However, from an Apex perspective, both of these components are still synchronous requests that are similar to standard Visualforce requests, and they count toward your concurrency limit.
Summary

The concurrent request limit attempts to ensure a positive user experience by limiting the number of synchronous Apex requests running for more than 5 seconds. Once the limit is reached, new synchronous Apex requests are denied. This behavior can be disruptive to your work. Therefore, it is easier to avoid this limit when designing new applications than it is when tuning live applications. You can accomplish this goal by ensuring that your users’ workflows do not include synchronous requests that take longer than 5 seconds.

Some useful tips:
Convert synchronous processes to asynchronous processes. Batch Apex might be a viable alternative. Limit synchronous Web service callouts.
Use the Streaming API instead of polling
Tune SOQL and DML operations. Make sure that your queries are selective. Limit the number of records in your list views. Avoid data skew.

Understand usage of fields in an object using field trip

In a huge organization where we have many custom and standard objects and when we create various fields as per the requirements, there are chances that we end up creating multiple fields and at times might not be using those fields as needed or there may be instances where in we end up the Salesforce limit of field creation per object i.e. 1000 and then we have to look out for options which fields can we delete to accommodate new fields.Eliminating unnecessary fields will help with user adoption and efficiency and makes your org clean. So how can we achieve this i.e. underutilized fields?

We have an application called as Field trip that does this job for us, we have to install this manage package and this app gives us a very clear picture of the percentage utilization of fields across all the objects whether its standard object or custom object. This app can be downloaded from an App exchange for free!!!!

Field Trip lets you analyze the fields of any object, giving you instant insight into what percentage of your records (or a subset) have that specific field populated. Run reports on the standard and custom fields you have in Salesforce for a better understanding of which field are important to your organization.

With a simple install, an intuitive user interface, and an easy-to-export report, Field Trip has made analyzing your fields quick and painless.

Once installed, simply name your trip, select an object (e.g. Accounts) and, optionally add a filter (for record subsets). Then you will receive a report detailing field usage (or lack thereof), available for simple export.

For more details visit : https://appexchange.salesforce.com/listingDetail?listingId=a0N30000003HSXEEA4

Using this link you can download this app for your org and check for the utilization of fields in an object.

Understand your code for a new org

Examining your code base can seem daunting. Especially if you’re new to an org or if your org has lots of code. But understanding how the different pieces of your org relate to one another is an essential, necessary part of identifying how to begin managing your org in more precise, meaningful units.

Type of Code	What to look for	Questions to ask
Triggers	1. Trigger patterns 2. Trigger logic	Does your org have one trigger per object? Is there business or application logic written directly in a trigger? Do triggers “hand off” logic or functionality to other classes (aka trigger handlers)?
Apex Classes	1. Naming conventions 2. Comments 3. API Version	Do Apex classes use common prefixes or even namespaces to group units of code? Do classes have similar names, based on functionality? Is the purpose and authorship of code documented in comments? Do classes have comments that help clarify function? What API versions do classes use?
Apex Tests	1. Test patterns/units 2. Code coverage 3. Test data handling	How do tests relate to other code? Does each class have its own test? Are your tests organized into functional groups? Are there parts of your code base not covered by tests? Do your tests depend on common data factories or static resources? Do any of your tests use the 'seeAllData=True' annotation, or run on an API version earlier than 24?
Lightning Components and Events	1. Naming conventions 2. Comments 3. Apex controllers 4. API Version	Do components use common prefixes or even namespaces to create groups? Do components have clear names, related to functionality? Are Lightning events scoped to be application events or component events? Are the purpose and authorship of components and events clearly documented in comments or Aura documentation files? Do components use Apex controllers? What API versions do components and events use?
Visualforce	1. Naming conventions 2. Comments 3. Apex controllers 4. API Version	Do Visualforce pages and components use common prefixes or even namespaces to create groups? Do pages have clear names, related to functionality? Do pages use Apex controllers? What API versions do pages use? Are pages used with any email templates?

These pieces help you identify patterns within the code in your org. But these techniques may not help you understand every piece of your code base. Or, if your code base doesn’t seem to be consistently organized, you may need to try other ways to discover how your org’s code is connected.

This is where the new Dependency API can help.

Understand configuration of your new org/Salesforce Optimizer

When you are assigned a new project, it is not easy to understand the use case for all.

How can you start looking at things you’ve built with clicks and not with code?

One way to get started is to use the Salesforce Optimizer.

This tool can recommend ways to improve some of the features in your Salesforce implementation. After you’ve looked at your Optimizer report, you can look more deeply into your org’s processes and declarative customizations.

So what should you look for?

Type of Customization	What to look for	Questions to ask
Process Builder	1.Object-related patterns 2. Active/inactive versions 3. Process logic	How many processes exist per object? Are processes clearly named? How many inactive versions exist per process? Do decision nodes have clear logic? Are commonly used actions grouped into invocable processes?
Workflow Rules	1. Object-related patterns 2. Active/inactive rules 3. Action logic	How many workflow rules do objects have? Are some objects busier? Are rules clearly named, with descriptions? How many active and inactive rules exist on objects? What kinds of actions do rules execute? Do rules carry out any cross-object field updates?
Flow/Visual Flow	1. Naming conventions 2. Object-related patterns 3. Active/inactive versions 4. Flow logic 5. Flow screens	Do flows use prefixes or similar names to create groups? Do flows have names clearly related to functionality? Do flows have clear, up-to-date descriptions? What object(s) does a flow interact with? What is the relationship between inactive flows or flow versions and active flows? Do flows put common functionality into subflows, invocable actions or quick actions? If flows have screens, are they based on Lightning components? Do screens depend on certain objects and fields?
Objects and Fields	1. Naming conventions 2. Record types 3. Page layouts 4. Permissions 5. Action overrides	Were custom objects created that duplicate standard object behavior? Do multiple business units use the same objects or fields? Are business logic and validations differentiated by record types? Do objects and fields have clear, up-to-date descriptions?

You want to create a clear sense of how well organized your processes and declarative customizations have been to date. If you find that your org isn’t as organized as you’d like, that’s OK. Now is the time to identify places where your team can work to increase quality and develop some standards that can help you build a healthier org moving forward. You may also identify projects that you want to tackle first, to clean up pieces of your org.

Understand your code for a new org