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

I will begin our blog on Java Tutorial with an incredibly important aspect of java development:  memory management.  The importance of this topic should not be minimized as an application's performance and footprint size are at stake.

From the outset, the Java Virtual Machine (JVM) manages memory via a mechanism known as Garbage Collection (GC).  The Garbage collector

• Manages the heap memory.   All obects are stored on the heap; therefore, all objects are managed.  The keyword, new, allocates the requisite memory to instantiate an object and places the newly allocated memory on the heap.  This object is marked as live until it is no longer being reference.
• Deallocates or reclaims those objects that are no longer being referened. 
• Traditionally, employs a Mark and Sweep algorithm.  In the mark phase, the collector identifies which objects are still alive.  The sweep phase identifies objects that are no longer alive.
• Deallocates the memory of objects that are not marked as live.
• Is automatically run by the JVM and not explicitely called by the Java developer.  Unlike languages such as C++, the Java developer has no explict control over memory management.
• Does not manage the stack.  Local primitive types and local object references are not managed by the GC.

So if the Java developer has no control over memory management, why even worry about the GC?  It turns out that memory management is an integral part of an application's performance, all things being equal.  The more memory that is required for the application to run, the greater the likelihood that computational efficiency suffers. To that end, the developer has to take into account the amount of memory being allocated when writing code.  This translates into the amount of heap memory being consumed.

Memory is split into two types:  stack and heap.  Stack memory is memory set aside for a thread of execution e.g. a function.  When a function is called, a block of memory is reserved for those variables local to the function, provided that they are either a type of Java primitive or an object reference.  Upon runtime completion of the function call, the reserved memory block is now available for the next thread of execution.  Heap memory, on the otherhand, is dynamically allocated.  That is, there is no set pattern for allocating or deallocating this memory.  Therefore, keeping track or managing this type of memory is a complicated process. In Java, such memory is allocated when instantiating an object:

String s = new String();  // new operator being employed
String m = "A String";    /* object instantiated by the JVM and then being set to a value.  The JVM
calls the new operator */

There are many excellent opportunities for IT professionals to present themselves to corporate entities for future consulting positions. You can find yourself in your next consulting engagement if you are willing to combine your IT skill-set, a good amount of corporate research and a bit of old fashioned moxie. Contrary to popular practice for applying for jobs through placement agencies and recruiters, it’s possible to meet with hiring managers, representing your firm, you, directly.

Although recruiters may not take a fee directly from you, the fact that they charge a fee for their services to a company after your placement may keep them from being able to place you. On the other hand, corporations searching for individuals with advanced knowledge of IT functions cannot rely on the friends and family of current employees to find superior consults in all fields.

What are some other options? First take the time to research corporations you would like to consult with. Look for the ones that most likely are complementary to your area of expertise because of the goods they produce or the services they provide to the public. Or you may opt to choose a company that is geographically close to where you live for the convenience of a short daily commute.  

Another way to find your next consulting job is to actively scan the news and see what corporations are making waves within their individual marketplaces. This is a good indicator of possible expansion and the need to hire on a contractual basis. Another good indicator of a need for IT professionals is a mention of a company relocation or expansion. Growth or renovation of office environments is often accompanied by a modernization of IT systems. Current IT team members may not be relocating or might not be familiar with systems other than the ones they already service.

Do as much research as possible about each corporation from their own websites and other sources dedicated to their particular field of endeavor. This gives you the edge in being able to speak about the IT systems they already have in place or your ideas for adapting their line of work or new product with the use of an IT system advancement. Their websites will often have a list of their corporate management. Make sure you address your cover-letter and resume to not only the Director of Human Resources, but to all executives in charge of their IT departments. Be specific in your abilities and the fact that you can be flexible with hiring arrangements.

Attend job fairs that have an emphasis on the more technical fields. When possible, also circulate your resume both digitally and in paper format to smaller and mid-sized companies. These corporations may not be able to maintain their own full-time IT group for fiscal reasons and your consulting prowess may be able to “save the day” for them in an emergency. You can become part of a corporate team on your own; all it takes is additional work on your part. However after your consultant job placement, you will be pleased that your efforts have succeeded so well.