In programming, memory leaks are a common issue, and it occurs when a computer uses memory but does not give it back to the operating system. Experienced programmers have the ability to diagnose a leak based on the symptoms. Some believe every undesired increase in memory usage is a memory leak, but this is not an accurate representation of a leak. Certain leaks only run for a short time and are virtually undetectable.

Memory Leak Consequences

Applications that suffer severe memory leaks will eventually exceed the memory resulting in a severe slowdown or a termination of the application.

How to Protect Code from Memory Leaks?

Preventing memory leaks in the first place is more convenient than trying to locate the leak later. To do this, you can use defensive programming techniques such as smart pointers for C++.  A smart pointer is safer than a raw pointer because it provides augmented behavior that raw pointers do not have. This includes garbage collection and checking for nulls.

If you are going to use a raw pointer, avoid operations that are dangerous for specific contexts. This means pointer arithmetic and pointer copying. Smart pointers use a reference count for the object being referred to. Once the reference count reaches zero, the excess goes into garbage collection. The most commonly used smart pointer is shared_ptr from the TR1 extensions of the C++ standard library.

Static Analysis

The second approach to memory leaks is referred to as static analysis and attempts to detect errors in your source-code. CodeSonar is one of the effective tools for detection. It provides checkers for the Power of Ten coding rules, and it is especially competent at procedural analysis. However, some might find it lagging for bigger code bases.

How to Handle a Memory Leak

For some memory leaks, the only solution is to read through the code to find and correct the error. Another one of the common approaches to C++ is to use RAII, which an acronym for Resource Acquisition Is Initialization. This approach means associating scoped objects using the acquired resources, which automatically releases the resources when the objects are no longer within scope. RAII has the advantage of knowing when objects exist and when they do not. This gives it a distinct advantage over garbage collection. Regardless, RAII is not always recommended because some situations require ordinary pointers to manage raw memory and increase performance. Use it with caution.

The Most Serious Leaks

Urgency of a leak depends on the situation, and where the leak has occurred in the operating system. Additionally, it becomes more urgent if the leak occurs where the memory is limited such as in embedded systems and portable devices.

To protect code from memory leaks, people have to stay vigilant and avoid codes that could result in a leak. Memory leaks continue until someone turns the system off, which makes the memory available again, but the slow process of a leak can eventually prejudice a machine that normally runs correctly.

Related:

The Five Principles of Performance

In Demand IT Skills

A business rule is the basic unit of rule processing in a Business Rule Management System (BRMS) and, as such, requires a fundamental understanding. Rules consist of a set of actions and a set of conditions whereby actions are the consequences of each condition statement being satisfied or true. With rare exception, conditions test the property values of objects taken from an object model which itself is gleaned from a Data Dictionary and UML diagrams. See my article on Data Dictionaries for a better understanding on this subject matter.

A simple rule takes the form:

if condition(s)

then actions.

An alternative form includes an else statement where alternate actions are executed in the event that the conditions in the if statement are not satisfied:

if condition(s)

then actions

else alternate_actions

It is not considered a best prectice to write rules via nested if-then-else statements as they tend to be difficult to understand, hard to maintain and even harder to extend as the depth of these statements increases; in other words, adding if statements within a then clause makes it especially hard to determine which if statement was executed when looking at a bucket of rules. Moreoever, how can we determine whether the if or the else statement was satisfied without having to read the rule itself. Rules such as these are often organized into simple rule statements and provided with a name so that when reviewing rule execution logs one can determine which rule fired and not worry about whether the if or else statement was satisfied. Another limitation of this type of rule processing is that it does not take full advantage of rule inferencing and may have a negative performance impact on the Rete engine execution. Take a class with HSG and find out why.

Rule Conditions

The job market is extremely tight these days, with several qualified workers being available for each empty position. That means that should you find yourself looking for work, for whatever reason, you need to make sure your interview skills are up to snuff. We will be taking a look at a variety of different tips that will help ensure your success during the interview process, including how to make sure your employers know about your C training experience. Here are some others:

• Do your own research in advance – Before you even step through the doorway to initiate the application process with a company, you should already know quite a bit about it. Investigate the corporate culture, speak with contacts who have experience with the firm, or search online; however you do it, having as much information as possible can really help you get an advantage during the hiring process. If you have specific experience, such as C training, that is of exceptional value to the firm you are applying to you can market yourself more effectively to the hiring agent.
• Dress Appropriately – In a perfect world, programming skill and experience such as C training should be the only factors in consideration when looking at a prospective hire; in real life this is often not the case. Don’t miss out because you gave a bad impression to someone, and strive to look your absolute best during your job interview. It is unfortunate, but the IT industry in particular tends to have a reputation for lacking in this department, so breaking the mold can be of great benefit to you.
• Be ready to interview at all times – You may be surprised how often job candidates are asked to participate in an off-the-cuff phone interview on the spot. Same-day in person interviews also are rising in popularity. Make sure you are always able to respond quickly if these situations come up and you get a fast interview. Memorize a few points in advance you can use to pump yourself up, such as an anecdote about your C training or other particular skills you may possess.

Job interviews are notoriously stressful for many people. Using simple tips like these can help you to prepare in advance for situations you may encounter during the interview process, and help you ultimately secure that new job. Make sure to emphasize whatever makes you special as an individual, such as your extensive C training.

From Brennan's Blog which is no longer up and running: