async-profiler Aracı

Giriş

Flame graph üretir, grafiği nasıl yorumlayacağımızı anlatan bir yazı burada. Kullanım şöyle

asprof -d 30 -f flamegraph.html <PID>

Eventual Immutability

Giriş

Bu konuyu ilk defa burada gördüm. Nesneyi mutable olarak yarattıktan sonra belli bir noktada freeze() metodunu çağırıyoruz ve bundan sonra nesne immutable oluyor.

JEP 491 - Synchronize Virtual Threads without Pinning.

Giriş

Açıklaması şöyle

Improve the scalability of Java code that uses synchronized methods and statements by arranging for virtual threads that block in such constructs to release their underlying platform threads for use by other virtual threads. This will eliminate nearly all cases of virtual threads being pinned to platform threads, which severely restricts the number of virtual threads available to handle an application's workload.

synchronized block kullanıyorsak Virtual Thread pinned oluyor. Bu JEP ile artık olmuyor

IntelliJ Idea Comment İçin Code Style

Comment At Firt Column

Cevap burada

• Settings | Editor | Code Style | Java | Code Generation | Comment Code | Line comment at first column -> Uncheck
• Settings | Editor | Code Style | Java | Code Generation | Comment Code | Block comment at first column -> Uncheck
• Settings | Editor | Code Style | Java | Wrapping and Braces | Keep when reformatting | Comment at first column -> Uncheck

Ayrıca Method Call Argument uzunsa ayrı satıra gelsin diye

• Settings | Editor | Code Style | Java | Wrapping and Braces | Method Call Arguments | -> Wrap if long

Ayrıca Chained method calls her biri ayrı satıra gelsin diye

• Settings | Editor | Code Style | Java | Wrapping and Braces | Chanied Method Calls | -> Wrap always

javadoc komutu

Örnek

Şöyle yaparız. docs/index.html dosyasını oluşturur

javadoc --enable-preview --source 22 -d docs Calculator.java

JMeter CLI

CLI vs Non-CLI

Açıklaması şöyle

JMeter has two modes: CLI and Non-CLI. .... CLI mode doesn't have any user interface. But Non-CLI mode has a user interface where you can point-and-click and interact with the JMeter.

Non-CLI mode should be used for recording, scripting, and smoke testing. This mode utilizes more resources (CPU and memory). CLI mode must be used for load testing, stress testing, and other forms of performance testing as well as for CI/CD pipelines. This mode doesn't eat up more resources as there is no user interface to load and render.

Örnek

Şöyle yaparız

jmeter -n -t test_plan.jmx -l test_results.jtl

Java record İle Yapılamayacak Şeyler

1. Records Cannot Extend Another Class

2. Records Cannot Be Extended

Örnek

Şu kod derlenmez

public class PremiumRecord extends InsuranceRecord {…}

3. Records Cannot Have Additional Instance Fields

Örnek

Şu kod derlenmez

public record InsuranceRecord(String type, float premium) {
  private String policyNumber;  // This won't compile
}

4. Private Canonical Constructors Are Not Allowed

Örnek

Şu kod derlenmez

public record InsuranceRecord(String type, float premium) {
  private InsuranceRecord(String type, float premium) {
    this.type = type;
    this.premium = premium;
  }
  public static InsuranceRecord newInstance(String type, float premium) {
    return new InsuranceRecord(type, premium);
  }
}

5.  Records Cannot Have Setters

Örnek

Şu kod derlenmez

public record InsuranceRecord(String type, float premium) {
  public void setType(String type) {
    this.type = type;  // Won't compile
  }
}