JVM G1GC Tuning Methods

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By Gi Pyeong Lee
jvm g1gc tuning

Introduction to JVM G1GC

As a Garbage Collector for the Java Virtual Machine (JVM), G1GC became available starting from JDK 7 Update 4. Unlike the previous garbage collector CMS, G1GC uses a method of partitioning and managing memory. This method aims to increase collection speed and reduce the impact on application response time during garbage collection.

G1GC manages memory by dividing it into multiple small areas. These areas are called Regions. These Regions are divided into three types: Eden, Survivor, and Old. Eden is where newly created objects are stored. Survivor is the area where objects from Eden are moved. Old is the area where moved objects are stored. Each area has its own garbage collection.

G1GC uses several algorithms in the process of managing these Regions. These algorithms are as follows:

  • Collection Priority Algorithm
  • Memory Usage Algorithm
  • Garbage Collection Redistribution Algorithm

G1GC uses these algorithms to efficiently manage memory and optimize garbage collection operations. This can reduce application response time and increase collection speed.

G1GC has the advantage of being easy to use and capable of improving application performance. However, this method has relatively complex memory management, and appropriate tuning is required to improve application performance.

G1GC Tuning Strategy

G1GC is a garbage collector added starting from Java 8, and unlike previous collectors, it uses a method of partitioning and managing memory. This uses a method of dividing memory into multiple stages for fast collection speed and prioritizing the collection of areas with high memory usage.

The methods for tuning G1GC to maximize performance are as follows:

Heap Size Adjustment

G1GC can adjust collection speed by adjusting the heap size. For example, reducing the heap size in situations where memory is heavily used increases collection speed, and increasing the heap size in situations where memory is lightly used slows down collection speed.

Memory Usage Limit

G1GC can adjust collection speed by limiting memory usage. This is a method of limiting memory usage for fast collection when the limited memory usage is exceeded. For example, using the -XX:MaxGCPauseMillis option can limit the collection speed.

Collection Cycle Adjustment

G1GC can adjust collection speed by adjusting the collection cycle. If the collection cycle becomes faster, the collection speed becomes faster, and if the collection cycle becomes slower, the collection speed becomes slower. For example, using the -XX:MaxGCPauseMillis option can adjust the collection cycle.

Collection Frequency Adjustment

G1GC can adjust collection speed by adjusting collection frequency. If collection frequency increases, collection speed increases, and if collection frequency decreases, collection speed decreases. For example, using the -XX:GCTimeRatio option can adjust the collection frequency.

Priority Collection Region Setting

G1GC can adjust collection speed by setting priority collection regions. This is a method of prioritizing the collection of regions where memory is heavily used. For example, using the -XX:InitiatingHeapOccupancyPercent option can set the priority collection regions.

G1GC Tuning Option Configuration

G1GC is a new garbage collector introduced in Java 8, providing various tuning options to improve performance and responsiveness. Setting these options appropriately is very important to fully utilize system performance.

Garbage Collection Policy

G1GC provides various garbage collection policies. These policies determine the optimal timing for garbage collection by considering factors such as memory usage, response time, and synchronization between threads. To this end, you can set the garbage collection policy using the -XX:G1GCHeapRegionSize option. This option specifies the size of memory to be used before each garbage collection operation is performed. For example, using the option -XX:G1GCHeapRegionSize=2M will use 2MB of memory before each garbage collection operation is performed.

Synchronization Between Threads

G1GC provides various tuning options to minimize synchronization between threads. The -XX:G1ConcRefinementThreads option specifies the number of threads to use to minimize synchronization between threads during garbage collection operations. For example, using the option -XX:G1ConcRefinementThreads=4 uses 4 threads during garbage collection operations.

Memory Usage

G1GC provides various tuning options to minimize memory usage. The -XX:G1MixedGCLiveThresholdPercent option can be used to minimize memory usage during garbage collection operations. This option specifies the maximum percentage of memory usage to be used during garbage collection operations. For example, using the option -XX:G1MixedGCLiveThresholdPercent=85 specifies the maximum percentage of memory usage during garbage collection operations to 85%.

G1GC provides various tuning options to improve performance and responsiveness. Setting these options appropriately is very important to fully utilize system performance. It is important to set appropriate tuning options by considering garbage collection policy, synchronization between threads, and memory usage.

Analysis of G1GC Tuning Results

G1GC is a garbage collector for the Java HotSpot VM, used to reduce garbage collection time and minimize memory usage. G1GC tuning is necessary to improve application performance. Several parameters can be adjusted for G1GC tuning.

Parameters that can be adjusted for G1GC tuning include:

  • Stack Size
  • Stack Tracing
  • Stack Compression
  • Stack Inlining
  • Stack Overflow Detection
  • Stack Overflow Handling
  • Stack Reallocation
  • Stack Reallocation Limit
  • Stack Reallocation Time
  • Stack Reallocation Interval
  • Stack Reallocation Ratio

To analyze G1GC tuning results, you must monitor and analyze the application’s performance. To monitor application performance, you must use performance monitoring tools. These tools measure the application’s memory usage, CPU usage, garbage collection time, etc.

To analyze G1GC tuning results, you must analyze the application’s performance monitoring data. By analyzing data such as memory usage, CPU usage, and garbage collection time, you can verify whether G1GC tuning improves the application’s performance.

Analyzing the results of G1GC tuning methods allows you to check if the application’s performance has improved. You can also check if the application’s memory usage and CPU usage are reaching appropriate levels.

Through G1GC tuning methods, you can improve application performance. You can reach appropriate levels of memory usage and CPU usage, and reduce garbage collection time. To achieve this, you need to adjust several parameters and use performance monitoring tools to analyze the results.