Concurrency Testing: Ensuring System Stability Under Parallel Use

Concurrency testing (also known as concurrent testing) is a technique used to detect possible defects while multiple users or concurrent users in performance testing scenarios access an application simultaneously. In software quality assurance and concurrency in software engineering, this form of testing plays a crucial role in detecting synchronization issues

Let us understand concurrency testing through an example:

Many of us make use of eCommerce websites such as Amazon to do online shopping. There comes a situation when multiple users log in to the website simultaneously and end up ordering the same product.

This requires maintaining the order in separate accounts without any confusion. This is an example of concurrent testing, where multiple users act on the same resource in real time, requiring accurate synchronization and resource management.

Why is Concurrency Testing Important?

Concurrency testing is usually done for two reasons

1. How does multiple user access at the same time affect the running process of a database or an application?

2. Determines how deadlocking, locking, single-threaded code, and constraining affect the resources that are shared.

Advantages of Concurrency Testing:

Here is a list of advantages of the Concurrency testing of an application:

• It significantly decreases the effort for testing an application or database as it restricts the scope of general concurrent communication lines.
• One can review just a fragment of the code without disturbing the whole code with the help of a specific value named encapsulation value.

After checking the processes of a concurrent program, it is updated with the reliability and vigor of the application.

Both developers and testers rely on concurrent testing to ensure their applications can handle multiple users efficiently, especially in high-load scenarios such as performance testing. Identifying bottlenecks caused by concurrent users in performance testing helps improve scalability.

Disadvantages of Concurrency Testing:

Concurrency testing, while valuable, also comes with a few notable disadvantages or limitations.

• There is no special platform since very few development steps are taken during concurrent testing. Due to this unoptimized situation, multiple outlets are required to perform that whenever simultaneous testing is done.
• Since concurrent programs are challenging to test, the defects are hard to find without vigorous testing.
• Concurrency testing is highly time-consuming. The results of the operating functions on any part of the code do not return the outcome immediately. Instead, the result is returned later through a sort of notification or a separately designed callback function.
• Without proper information representation of the flow of the actual program in the call stack, it is difficult to detect the defects. Thus, defragmenting the testing process.
• There is an interconnection of all the concurrent systems that merge and interact with themselves while the program execution process is on. Thus, controlling the contemporary process becomes difficult as the interaction of the systems produces multiple paths of execution.
• Concurrent programs have a reputation for failing more often than regular sequential programs.
• Due to the multiple paths of execution, debugging the program becomes very troublesome.

Despite these challenges, concurrency testing remains critical in software quality assurance. The following techniques help ensure systems behave as expected under real-world, simultaneous user activity.

Concurrency Testing Techniques:

Several proven concurrency testing techniques help uncover issues in systems with multiple threads or users.

• Reviewing Code – This process is quite time-consuming. Because you need to review and check every block of embedded code and its subsequent structure thoroughly.
• Static Analysis- This is a standard process to evaluate and check the code thoroughly evaluated and checked before the final execution process. This process aims to determine bugs and errors of any sort in the program.
• Con Testing- This method eliminates unwanted synchronization errors from a particular program, hence reducing running deficiencies.
• Reachability Testing- This type of testing requires a lot of subtests in its follow-up. Hence, you need to select some precisely verified codes for reachability testing.
• Fuzz Testing- This is a random test where the user deliberately inserts wrong code to see how the program’s execution reacts.
• Random Testing- This is a valuable method to test multiple threads mandatorily to improve the quality of the results. Hence, it has a vast coverage area.
• Extending Concolic Testing- This type of testing is suitable for multiple concurrent programs and numerous sequential programs. It is easily expandable in size and helps a lot.

Types of Concurrency Defects:

Let’s explore the most common defects found during concurrency testing.

• Deadlock: This is a specific failure condition where the code stops working due to the deficiency of a particular resource. Here, one of the components is locked by another one and vice versa. For example, a defect caused by two components does not move forward until the resource is free to use.
• Livelock: A failure condition where a concurrent component never finishes its execution process due to the lack of necessary resources, termed as the high-priority component.
• Starvation: In this particular failure condition where the concurrent component has to wait indefinitely for its execution to complete because some other component occupies the resource it needs.
• Suspension: It is a failure condition where the concurrent component is forced to wait for so long that when the resource is available to share, the execution cannot happen properly due to the delay.
• Race Condition: A Race condition is a failure condition where too many operations can lead to unexpected and inappropriate behavior of the system. This usually happens when you do not appropriately authorize the resources, and there is excessive access to them. The simultaneous errors can lead to the corruption of the whole system.
• Priority Inversion: It is an unwanted failure condition that is first served for the low-priority concurrent component. Then, before executing a high-priority concurrent component, it leads to the disruption of the whole process.

Conclusion:

To summarize, all the above points elucidate that concurrency testing needs development and optimization of the highest sort in itself to be better used in the future.

But at the same time, it is also one of the effective techniques used by businesses to streamline operations in a better manner.

For more details, readers may also refer to TestGrid.