- How would you improve performance of a Java application? …
- How would you refresh your cache? …
- How would you refresh your cache if your database is shared by more than one application? …
- How would you detect and minimize memory leaks in Java?
3 Answers Every Performance Tuning Experts Always Seeking
What are the key areas that impact the performance of Java programs?
A lot of factors can impact the performance of an application developed in Java programming language. At a high level following areas can be optimized to improve Java application performance.
What are the benefits and dis-advantages of garbage collector?
Benefits:
Dis-advantages:
Java Performance Tuning is a process of improving the performance of a Java application. This process can involve optimizing code, improving the JVM settings, or changing the way the application is deployed. Java Performance Tuning is a complex topic, and interviewers may ask questions to test your knowledge and understanding of the process. In this article, we review some commonly asked Java Performance Tuning questions and provide tips on how to answer them.
There are a few different tools available in Java to monitor memory usage. The most common tool is the Java Virtual Machine Tool Interface (JVMTI). This tool is used to provide low-level access to the Java virtual machine. Other tools include the Java Mission Control (JMC) and the Java Development Kit (JDK).
The best way to get started with optimizing an application for better performance is to use a profiler to identify which areas of the code are taking the longest to execute. Once you have identified these areas, you can then focus on optimizing them specifically. This may involve making changes to the code itself, or to the way that the application is configured.
A sleeper thread is a Java thread that is used to pause the execution of a program for a specific amount of time. This can be useful in a number of situations, such as when you want to give another thread a chance to run or when you want to slow down the execution of a program to make it more readable.
MBeans are Java objects that expose a management interface to resources in the Java virtual machine (JVM). MBeans can be used to monitor and manage the JVM, as well as to monitor and manage applications running in the JVM. MBeans can be used to retrieve information about the JVM, such as memory usage, thread counts, and garbage collection statistics. MBeans can also be used to manage applications running in the JVM, such as starting and stopping applications, changing application configuration, and monitoring application performance.
When the Java language was created, Sun engineers decided that developers should not be responsible for managing the memory used by the objects they create. Instead, a garbage collection routine would be part of the JVM; this routine identifies objects that are no longer in use and deletes them from memory.
A full garbage collection cycle will run for several seconds — or potentially even several minutes. Furthermore, garbage collection routines cant be scheduled. Imagine youre running a high-volume trading program. Now imagine a garbage collection routine happening two minutes before the stock market closes. A stop-the-world event on the JVM at that moment in time would lead to a large number of unhappy application users.
When an object is first created, it is placed in the eden space. If garbage collection occurs and the object is still referenced, it gets moved to the survivor space. If enough garbage collections happen and an object in the survivor space never gets collected, it is then moved to the tenured space.
Eden, survivor and the tenured space are all garbage collected separately, with eden collected the most often and the tenured space collected the least. This helps to improve performance, as the weak generational hypothesis tells us that long-lived objects are likely to remain active, making an inspection of their garbage collection eligibility a waste of time.
However, its worth mentioning that while the specification says the JVM may ignore a call to System.gc(), the reality is that no current implementation does unless specifically configured to do so. “And even then, there is a tooling path that ignores that config,” says Java performance expert Kirk Pepperdine.
FAQ
How do you performance tune a Java application?
- Move to the Latest Stable Java Version.
- Size the Java Heap Memory Correctly.
- Set the Initial Java Heap Memory Size.
- Choose the Right Garbage Collection Algorithm.
- Tune the JVM Garbage Collector.
- Ensure your Web Container’s Thread Pool is Sized Correctly.
- Avoid Database Connection Delays.
How do you improve performance in Java?
- Avoid Writing Long Methods. …
- Avoid Multiple If-else Statements. …
- Avoid Getting the Size of the Collection in the Loop. …
- Avoid Using String Objects For Concatenation. …
- Use Primitive Types Wherever Possible. …
- Avoid Using BigDecimal Class. …
- Avoid Creating Big Objects Often. …
- Use Stored Procedures Instead of Queries.
How do you handle performance issues in Java?
- Use Regular Expressions Carefully.
- Avoid recursion when possible.
- Run Performance test suite.
- Use StringBuilder for concatenation of strings.
- Use the Stack and Avoid the Heap.
- Use Concurrency control strategy.
- Caching.
- Implement EnumSet.
What is garbage collection in Java interview questions?
