The Java programming language has been around for more than two decades. Since Java uses the Java Virtual Machine (JVM) and garbage collection mechanisms, it was initially slow in performance compared to other contemporary languages. However, its speed has since been improved thanks in part to a lot of updates in recent releases. The performance of JVM has been optimized considerably.
How to Improve Java Application Performance
Even though Java and JVM execution has been expedited, there are certain key strategies that you can leverage to improve the performance of applications developed in Java even further. This Java programming tutorial delves into some optimization tips for Java code, complete with code examples wherever appropriate.
Java Optimization: Avoid Writing Long Methods
One of the simplest ways a developer can improve their Java performance is to avoid writing long methods. If you code long methods, it will take your Java Virtual Machine more time to execute. The JVM is part of the Java Runtime Environment (JRE) and calls the main method in your program. The JVM is an acronym for Java Virtual Machine, which is responsible for providing an environment to execute Java programs, allowing Java applications to run on any operating system or machine.
If the methods in your application are small and concise, then they will not slow down your application. This is because keeping your methods short minimizes the amount of processing that needs to be performed and reduces the CPU cycles as well. Additionally, if a method is large, programmers can split it into multiple methods at suitable logical points to optimize the processing speed.
The Just-in-Time (JIT) compiler determines the optimizations needed to compile a method into native code based on previous executions in the interpreter mode. This leads to improved performance and more efficient code.
When your method is extensive, it will not be JIT compiled by the JVM; such methods are less likely to be inlined as well. On the contrary, if your method is short, it is ideal for JVM inlining and JIT compilation.
Avoid Using the BigDecimal Class
While the BigDecimal class is helpful for specific scenarios, it might hinder the performance of your applications. The more BigDecimal computations a Java developer performs, the slower their application will be. While the BigDecimal class guarantees precise accuracy for decimal and floating point numbers, it will degrade the application’s performance significantly if you use it too often. If you do not need the precision this class can provide, it is better to skip using BigDecimal and use long or double data types instead.
Use Primitive Types Wherever Possible
You can also use primitive types in your applications to reduce processing overhead and increase performance. It’s better to use an int instead of an Integer, or a double instead of a Double. While primitive types are stored in the stack, instances of classes, (i.e., objects), are stored in the garbage collected heap. Using primitive types allows your JVM to store the object in the stack and not in the heap. Using this method, your application’s performance can improve considerably, since the stack is faster than the heap with much less resource overhead.
Avoid Using Regular Expressions in Your Java Code
Regular expressions (Regex) are powerful, inexpensive, and straightforward to use. However, if you have to use regular expressions in computation-intensive code, it is advised to cache the pattern reference rather than compile it every time.
Perform Profiling and Load Testing
Profiling your Java application will reveal potential pain areas and bottlenecks. Identifying areas for improvement is the first step in enhancing the performance of Java applications. Trying to speed up an application without understanding where the most significant difficulties are is like tossing a dart at a dartboard while blindfolded.
Use Stored Procedures Instead of Queries
One of the most effective ways to improve your Java performance is to use stored procedures instead of queries. Queries are usually used when you want to retrieve data from a table or set of tables in your database, but they can be expensive, since they require a lot of processing from the application and database server. Stored procedures, on the other hand, are pre-compiled to machine code and only need to be compiled once, which makes them execute much faster than queries.
Use PreparedStatement Instead of Statement
The use of a prepared statement can improve your application’s performance by reducing the number of round trips required to execute an SQL statement. Since the PreparedStatement object is built once and executed several times, it offers an advantage over the Statement object for running parameterized queries. On the other hand, the Statement object is compiled and executed each time it is invoked. In addition, the PreparedStatement object is secure against SQL injection threats.
Select Only the Columns You Require in a Query
When retrieving data from a database, we execute a select query. You must not select columns that are not required. In other words, you should specify only the required columns. Choosing too many columns increases network traffic from the database to the application and impacts the application’s performance.
Use Caching in Java Applications
Caching is a method for enhancing web application speed by keeping requested data in memory for later reuse. Caching is a method of maintaining data (this can be servlets, commands, JSPs, or application data) between requests in memory so that future requests for the same piece of data or page can be obtained from memory. Proper use of caching can reduce latency, avoid network congestion, improve content availability, and reduce consumption of memory and CPU cycles.
It enhances application performance by allowing for quicker page rendering and fewer server resources. You can use caching to create scalable, high-performance applications. The Java Object Cache enhances server performance by maintaining local copies of objects that are costly to obtain or build. There are no constraints on the kind of item that may be cached or the object’s originating source.
String concatenation is expensive, although Java developers often need it in their applications. If you need string concatenation in your application, you must avoid using strings and the + operator. Instead, it would help if you took advantage of StringBuilder to prevent creating multiple string objects when performing string concatenation. If you do not require too much string concatenation, you can use the concat method of the String class rather than use a StringBuilder as an alternative.
Other Tips to Improve Java Performance
You can also improve Java performance by setting the initial Java heap size, avoiding recursion, acquiring resources late and releasing them early (i.e., database connections), fixing inefficient code, optimizing garbage collection routines, using faster database queries and stored procedures, choosing the right GC algorithm (Serial GC, Parallel GC, etc.), choosing the right GC, refactoring your code, or analyzing your code with an application performance monitoring tool.
Summary of Java Application Tips for Performance
You can take advantage of load testing tools and Application Performance Management (APM) solutions to measure and improve the performance of Java apps. While it is crucial to run load testing for different application scenarios, you should simultaneously monitor the CPU, IO, and heap memory.