Java memory analyzers are often seen as a geek’s tool, used by the backroom gurus when troubleshooting obscure software errors. Actually, they’re much more than this.
In this article we’ll look at how they can be used throughout the software lifecycle to improve quality, pre-empt production errors, and reduce costs. Designers, developers, testers, performance tuners and software support can all make use of memory analyzers to work towards a better product.
Let’s take a look at what a memory analyzer can do for us, and break it down into specific uses.
What Is a Java Memory Analyzer?
A Java memory analyzer allows us to look inside the JVM heap, view statistics and explore objects and their relationship to other objects. A good memory analyzer is also able to spot potential issues, such as possible memory leaks. In this article we’ll be using HeapHero to illustrate ways to use a memory analyzer. Since there are several analyzers available, your organization may use a different tool.
Most analyzers work from a heap dump, which is a snapshot of the heap at a given moment. Since it’s a large binary file, it would be impractical to try to extract information from it manually. It contains the class, incoming and outgoing references and content of every object in the heap.
If you’re not familiar with the JVM memory model, you may find it useful to watch this short video: JVM Explained.
The Software Lifecycle: When is a Java Memory Analyzer Useful?
A memory analyzer can be useful in most aspects of software development and maintenance. Let’s look at some practical uses.
1. Design Stage
In systems design, we’ll often consider a number of different design options, and we may build prototypes to test the feasibility and efficiency of different solutions. A memory analyzer can be extremely useful at this stage, allowing us to compare trade-offs between different options, and make informed decisions. It can also allow us to more accurately estimate hardware costs to make sure our chosen solution can be brought in within budget.
2. Development Stage
In the very early days of computing, when programmers were cheap and hardware was expensive, it was not unknown for a developer to spend half an hour figuring out how to save a couple of bytes of memory. As cheaper and cheaper RAM became available, the trend went the other way: who cares how much memory we’re using: let’s get the job done quickly.
This use-as-much-as-you like mentality doesn’t cut it in modern computing. Software may be developed for a wide range of platforms. It may need to work on a tiny device with limited RAM. It may run on an enormous cloud server, where your organization’s bills depend directly on how many resources the software uses. Small containers are an upcoming trend, and even large company servers are likely to be utilized to the maximum. Efficient memory usage is once again an important factor.
A memory analyzer is useful to a developer in the following ways:
- See exactly how much memory is used by data structures, allowing us to optimize code;
- Identify which methods are retaining memory, and for how long;
- Debugging: analyze exactly what’s happening in memory when things aren’t working correctly.
- Accurately predict memory requirements in production.
- Eliminate memory wastage. HeapHero produces statistics and a detailed breakdown of memory wastage, with recommendations for improving efficiency. See the screenshots below.
Fig: Memory Wastage Statistics by HeapHero
This chart is followed by a detailed breakdown of wastage in each category, for example:
Fig: Breakdown of Wastage by Duplicate Strings by HeapHero
3. Testing and Quality Assurance
A memory analyzer is extremely useful in this area, especially in a CD/CI pipeline where new releases are happening frequently. A memory analyzer can be used to:
- Accurately record memory usage, to ensure it’s within specs;
- Identify whether a new release is using more memory, creating more objects or retaining memory longer than a previous release. HeapHero is especially useful in this area, since it has the facility to compare old and new reports, and be integrated via API into testing procedures.
- Quickly solve memory-related problems that may be encountered in testing.
4. Preparation for Deployment
The statistics provided by a memory analyzer are invaluable for configuring memory parameters in the live system. They help make informed decisions regarding:
- The heap size;
- The size of young and old generation spaces;
- Fill factors for each space;
- Selecting and tuning the garbage collection algorithm.
5. In Production
The first and best-known use of a memory analyzer in production is to troubleshoot memory-related issues. This tool greatly simplifies the task of finding an elusive memory leak, which can lead to poor performance, timeouts, high CPU usage and system crashes. It can also highlight the need to adjust configuration parameters, and eliminate wasted memory.
The second use is in regular monitoring, which is essential for pre-empting production problems. By incorporating a memory analyzer into an automated monitoring process, and comparing old and new reports, we can predict memory issues before they become a problem, and take preventative action.
Memory Analyzers and Cost Benefits
Incorporating a Java memory analyzer into all stages of software development and live use can result in considerable cost savings.
Good decisions at the software development stage result in a much more stable system, with less delays in testing and QA. Cloud costs can be reduced by optimizing and reducing memory usage, and many costly production outages can be prevented.
A more stable system creates a better user experience, and clients are more likely to remain loyal to the company.
Since many memory analyzers are free, and easy to learn and use, there really is no downside to making the best use of this tool.
Conclusion
Java memory analyzers are much more than an essential troubleshooting tool. Many IT departments greatly underutilize these powerful utilities.
Making full use of memory analyzers can streamline development and testing, result in more stable systems, and facilitate effective forward planning.
They can be a great cost saver with virtually no outlay.
HeapHero has the added advantage, in that it can be integrated into CD/CI pipelines and automated system monitoring.
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