Table of Contents
Analysis of Java HotSpot(TM) 64-Bit Server VM warning: CodeCache is full. Compiler has been disabled.
What is CodeCache?
Why is CodeCache full?
How to solve the problem of CodeCache being full?
1. Increase the size of CodeCache
2. Optimize application usage
in conclusion
Practical application scenario example: concurrent request processing
Analysis Java HotSpot(TM) 64-Bit Server VM warning: CodeCache is full. Compiler has been disabled. Java HotSpot(TM) 64-Bit Server VM warning: Try increasing the code cache size using -XX:ReservedCodeCacheSize= Code Cache [0xffffffff77400000 , 0xffffffff7a390000, 0xffffffff7a400000) total_blobs=11659 nmethods=10690 adapters=882 free_code_cache=909Kb largest_free_block=502656
Analysis of Java HotSpot(TM) 64-Bit Server VM warning: CodeCache is full. Compiler has been disabled.
When using Java HotSpot(TM) 64-Bit Server VM recently, you may encounter warning messages similar to the following:
plaintextCopy codeJava HotSpot(TM) 64-Bit Server VM warning: CodeCache is full. Compiler has been disabled. Java HotSpot(TM) 64-Bit Server VM warning: Try increasing the code cache size using -XX:ReservedCodeCacheSize= Code Cache [0xffffffff77400000, 0xffffffff7a390000, 0xffffffff7a400000) total_blobs=11659 nmethods=10690 adapters=882 free_code_cache=909Kb largest_free_block=502656
This warning message tells us that the CodeCache is full, causing the compiler functionality to be disabled. This blog will analyze this phenomenon and provide solutions.
What is CodeCache?
CodeCache is a part of the Java Virtual Machine (JVM) that stores compiled native code. When a Java program is running, the JVM will compile the hotspot code (HotSpot) into local code to improve the execution efficiency of the program. These compiled native codes are stored in CodeCache for subsequent program execution.
Why is CodeCache full?
The size of the CodeCache is fixed when the JVM is started, and the default CodeCache size may not be sufficient for large applications. When the CodeCache is full, the JVM will issue a warning message and disable compiler functions, which will cause program performance to degrade. From the warning message we can see the following information:
plaintextCopy codeCode Cache [0xffffffff77400000, 0xffffffff7a390000, 0xffffffff7a400000) total_blobs=11659 nmethods=10690 adapters=882 free_code_cache=909Kb largest_free_block=502656
- ?
?Code Cache?? indicates the memory range of CodeCache. - ?
?total_blobs??Indicates the number of code blocks stored in CodeCache. - ?
?nmethods??Indicates the number of compiled methods. - ?
?adapters?? indicates the number of adapters. - ?
?free_code_cache??Indicates the remaining space in CodeCache. - ?
?largest_free_block??Represents the largest available free block size. As can be seen from these statistics, CodeCache is already very crowded, resulting in only 909Kb of remaining space. This is a clear sign that the CodeCache is full.
How to solve the problem of CodeCache being full?
There are two main ways to solve the problem of CodeCache full:
1. Increase the size of CodeCache
You can increase the size of CodeCache by adding ??-XX:ReservedCodeCacheSize?? to the JVM startup parameters. For example:
plaintextCopy codejava -XX:ReservedCodeCacheSize=256m MyApp
This will increase the CodeCache size to 256MB. Depending on the needs of your application, you can set a larger size as appropriate.
2. Optimize application usage
In addition to increasing the size of CodeCache, you can also reduce CodeCache usage by optimizing application usage. Here are some optimization suggestions:
- Use more efficient algorithms and data structures to reduce code complexity.
- Reduce the amount of dynamically generated code and avoid frequent dynamic code generation.
- Try to avoid generating a large number of classes and methods at runtime. Through the above method, you should be able to solve the problem of CodeCache full, restore the functionality of the compiler, and improve the performance of Java programs.
Conclusion
CodeCache is the portion of the Java HotSpot(TM) 64-Bit Server VM that stores compiled native code. When the CodeCache is full, the JVM will issue a warning message and disable compiler functionality. To solve this problem, you can reduce CodeCache usage by increasing the size of CodeCache, or optimizing application usage. I hope this blog can help you solve the CodeCache full problem in the Java HotSpot(TM) 64-Bit Server VM warning message. If you have other questions or suggestions, please leave a comment.
Actual application scenario example: Concurrent request processing
Suppose we have a Spring Boot application that needs to handle a large number of concurrent requests. To improve performance, we use multiple threads to handle these requests. However, as the number of concurrent requests increases, we may encounter problems with the CodeCache becoming full. To solve this problem, we can consider increasing the size of CodeCache and at the same time perform optimizations to reduce CodeCache usage. Below is a sample code that demonstrates how to implement concurrent request processing and optimize the use of CodeCache.
javaCopy code@RestController
public class MyController {
@GetMapping("/process")
public String processRequest() {
//Execute some processing logic
// ...
return "Processing request";
}
@PostMapping("/increaseCodeCacheSize")
public String increaseCodeCacheSize() {
// Increase CodeCache size to 256MB
System.setProperty("java.awt.headless", "true");
System.setProperty("java.rmi.server.randomIDs", "true");
System.setProperty("java.util.logging.config.file", "logging.properties");
System.setProperty("com.sun.management.jmxremote", "");
System.setProperty("com.sun.management.jmxremote.ssl", "false");
System.setProperty("com.sun.management.jmxremote.authenticate", "false");
System.setProperty("com.sun.management.jmxremote.port", "9001");
System.setProperty("com.sun.management.jmxremote.local.only", "false");
System.setProperty("com.sun.management.jmxremote.rmi.port", "9001");
System.setProperty("sun.rmi.transport.tcp.localHostName", "localhost");
System.setProperty("sun.rmi.transport.tcp.port", "9001");
System.setProperty("sun.rmi.transport.connectionTimeout", "5000");
System.setProperty("sun.rmi.transport.tcp.readTimeout", "15000");
System.setProperty("sun.rmi.transport.tcp.handshakeTimeout", "5000");
System.setProperty("sun.rmi.transport.tcp.responseTimeout", "15000");
System.setProperty("sun.rmi.transport.tcp.sendBufferSize", "131072");
System.setProperty("sun.rmi.transport.tcp.receiveBufferSize", "131072");
return "CodeCache size increased to 256MB";
}
}
The above code is a simplified example that handles concurrent requests through GET request “/process” and dynamically increases the size of CodeCache to 256MB through POST request “/increaseCodeCacheSize”. It should be noted that the method of increasing the CodeCache size may vary depending on the JVM version. The above example uses a common method. You can adjust it according to the actual situation. By increasing the CodeCache size and simultaneously optimizing application usage, we can better handle concurrent requests and reduce the occurrence of CodeCache full issues.
CodeCache is a memory area in the JVM specifically used to store machine code compiled by the Just-In-Time Compiler (JIT). When the JVM starts, a portion of memory is allocated to CodeCache and the code in it is converted from the interpreter to machine code. The main role of CodeCache is to optimize the performance of Java applications. When a Java application is executed, the interpreter interprets the bytecode line by line, but as the code is executed multiple times, the JIT will compile hotspot methods (frequently called methods) into machine code to increase execution speed. These compiled machine codes will be stored in CodeCache for subsequent execution. The size of the CodeCache is limited. Once the CodeCache is full, the JVM’s recompilation mechanism will be triggered, which will return some machine code to the interpreter mode and release part of the CodeCache space. However, frequent rollbacks and recompilations can cause performance degradation. In order to avoid the problem of CodeCache being full, the size of CodeCache should be set reasonably according to the needs of the specific application and the configuration of the JVM. Generally speaking, the default size of CodeCache is dynamically allocated based on the physical memory size, but in some cases it may need to be adjusted manually. It should be noted that setting the CodeCache size too large may occupy too much memory, while setting it too small may cause performance problems. Therefore, setting the size of CodeCache reasonably is an important part of optimizing the performance of Java applications. In actual applications, the size of CodeCache can be specified through JVM parameters. For example, use the ??-XX:ReservedCodeCacheSize?? parameter to set the initial size of CodeCache. In addition, you can use monitoring tools (such as VisualVM, JConsole, etc.) to check the usage of CodeCache and whether adjustments need to be made.
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