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♥ Top 10 causes of performance issues in Java

Cause #1: The JVM spends more time performing garbage collection due to improper Garbage Collection (GC) configuration. E.g. Young generation being too small. Heap size is too small (use -Xmx). The application footprint is larger than the allocated heap size. Wrong use of libraries. For example, XML based report generation

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Posted in FAQs Java Key Areas, Performance
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♥♦ 01: 30+ Writing low latency applications in Java interview Q&As

Have you seen job advertisements requiring Java candidates to work in real-time, low latency, and high throughput systems? Wondering what questions you will be asked? You will be quizzed on the low latency application you had recently worked on especially the outcomes in terms of the latencies, response times, and

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Posted in FAQs Java Key Areas, Judging Experience Q&As, Low Latency, Low latency & Asynchronous, Performance, Scalability

♦ 8+ JMeter performance testing interview Q&As

Performance testing is an important process of any software development. You can bring this up yourself to many open-ended questions like — Tell me about yourself? What are some of your recent accomplishments that you are proud of? Setting up a performance/load test script is always the first step in…...

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Posted in FAQs Code Quality, JMeter, JMeter Tutorial, member-paid, Performance, Performance Testing Q&A

♦ 9 Java Garbage Collection interview questions & answers to ascertain your depth of Java knowledge

Java Garbage Collection interview questions & answers to ascertain your depth of Java knowledge in building industry strength Java applications Q1. In which part of memory does Java collection occur? When does the garbage collection occur? In which thread does the GC run? Why is it knowing about GC is…...

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Posted in GC, JVM, member-paid, Performance
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♦ Monitoring/Profiling Java applications interview Q&A

Q1 How will you go about monitoring your Java application for potential performance or memory issues? A1 1. Visual VM for monitoring Java memory, CPU, threads, etc VisualVM is a visual tool integrating several command-line JDK tools and lightweight profiling capabilities. Designed for both production and development time use, it…...

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Posted in FAQs Java Key Areas, member-paid, Memory Management, Performance, QoS

♦ Processing large files efficiently in Java – part 1

Q1. What are the key considerations in processing large files? A1. Before jumping into coding, get the requirements. #1. Processing a file involves reading from the disk, processing (e.g. parsing an XML and transforming), and writing back to the disk. It is also a trade off in terms of what

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Posted in IO, Memory Management, Performance
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02: ♦ 13 Tips to write low latency applications in Java

Extends Writing low latency applications in Java interview Q&As. If the job description says “low latency” application, then be prepared. Even if “low latency” experience is not a requirement, all employers like candidates who can not only build systems that perform well, but also can stress test (e.g. JMeter), profile…...

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Posted in FAQs Java Key Areas, Judging Experience Q&As, Low Latency, Low latency & Asynchronous, member-paid, Performance, Scalability
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10: ♦ 8 Java Maps & Caching Data in Java Interview Q&As

Q1. What is the purpose of a Map interface in Java collection API? A1. A map is a set of associations between pairs of objects. One is known as a “key” and the other is known as a “value”. It is used very frequently in programming in case where for…...

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Posted in Collection and Data structures, member-paid, Memory Management, Performance

4 FAQ Performance tuning in Java interview Q&As

Q1. In your experience, what are some of the major causes of performance bottlenecks in Java applications? A1. Cause #1: The JVM spends more time performing garbage collection due to improper Garbage Collection (GC) configuration. E.g. Young generation being too small. Heap size is too small (use -Xmx). The application…...

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javap, jps, jmap, and jvisualvm tutorial – analyzing the heap histogram

Q1. Is there anything wrong with the code snippet shown below? A1. The above code creates too many “Integer” objects due to auto boxing. Q2. How do you know that the above auto unboxing and boxing code were executed? A2. Because of “javap“. “SumNumbers” is the class file in the

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Posted in Memory Management, Performance

JMeter for performance testing REST services with BeanShell

This post extends 8 JMeter Performance testing Interview Q&As to cover JSON HTTP post. Now a days, a single page interactive web sites are very popular, and they post JSON based data back to the server to create a new record or to update an existing record. Step 1: Firstly,…...

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Posted in JMeter, JMeter Tutorial, member-paid, Performance, Performance Testing Q&A

Processing large files efficiently – BigData & Hadoop – part 3

Q1. What are the different data sizes, and what technologies can be used to process them? A1. In general, data sizes can be classified as shown below. 1) Small size data is < 10 GB in multiple files. It fits in a single machine’s memory when you process them by…...

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Posted in IO, member-paid, Performance

Processing large files efficiently in Java – multi-threaded code – part 2

If you want to process medium sized data (e.g. 2 GB to 1 TB in multiple files) in Java, consider writing a batch job with Spring batch or Java EE 7.0 batch processing. If processing requires access to other systems, use “spring integration” with spring batch. This is also known…...

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Posted in IO, member-paid, Performance

Understanding service and socket timeouts in Java enterprise applications

Q. Why is it important to set proper timeout values in your applications? A. Security and performance. Security reason: it is often necessary to control how long a Web Service client or other valuable clients invoking valuable resources like database connections, transaction management, etc waits for a response after sending a

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Posted in Performance, QoS, Security

800+ Java Q&As – ♥Free | ♦FAQs

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