wind_jvm

my simple java virtual machine~

wind2412
197
34
C++

wind jvm

My simple java virtual machine

Environment Support

  • Supported Platforms: macOS, Linux
  • Not Supported: Windows (due to OS-specific dependencies in the underlying libraries)
  • Requirements:
    • C++14
    • Boost Library
    • JDK 8 (specifically rt.jar from Java 8)

Getting Started

macOS

  1. Install Boost Library:
    If Boost is not installed, run the following command:

    brew install boost

  2. Modify the Makefile:
    Update the linker command to use your local Boost library path.

  3. Configure config.xml:
    Set the path to your JDK 8’s rt.jar in the config.xml file.

  4. Compile Tests:
    Run the following command to compile the test Java code:

    make test

    Note: Test7 must be compiled using a debug version JVM. A precompiled classfile is already provided.

  5. Build the Project:
    Use the following command to compile the project:

    make -j 8

  6. Run Wind JVM:
    Navigate to the root directory of wind_jvm and execute the following command:

    ./bin/wind_jvm Test1

    Important: You must run the JVM from the root directory, or path detection may fail and cause exceptions.

  7. Enjoy!
    While this JVM is simple, it’s a fun project that may help spark your interest in virtual machine development.

Linux

  1. Install Boost Library:
    Run the following command to install Boost:

    sudo apt-get install libboost-all-dev

  2. Configure config.xml:
    Set the <linux> section in config.xml to point to your JDK 8’s rt.jar path.

  3. Follow steps 4–6 in the macOS section above.

Usage Examples

Simple Example

From the wind_jvm folder, run Test3:

./bin/wind_jvm Test3

Output:

Hello, wind jvm!

Complex Example (Triggering GC)

From the wind_jvm folder, run Test7:

> ./bin/wind_jvm Test7

Sample output is (with internal debugging messages):

signal gc...
===------------- ThreadTable ----------------===
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[0]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[0]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
init_gc() over.
===------------- ThreadTable ----------------===
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[0]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[0]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
block!
block!
===------------- ThreadTable ----------------===
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
block!
===------------- ThreadTable ----------------===
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
===------------- ThreadTable ----------------===
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
===------------- ThreadTable ----------------===
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
===------------- ThreadTable ----------------===
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
===------------- ThreadTable ----------------===
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
block!
===------------- ThreadTable ----------------===
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c587000], is the [4] thread, Thread Oop address: [140,440,780,815,488], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
block!
===------------- ThreadTable ----------------===
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c60a000], is the [5] thread, Thread Oop address: [140,440,780,852,720], state:[1]
pthread_t :[0x70000c587000], is the [4] thread, Thread Oop address: [140,440,780,815,488], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
===------------- ThreadTable ----------------===
pthread_t :[0x70000c68d000], is the [6] thread, Thread Oop address: [140,440,780,889,952], state:[0]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c60a000], is the [5] thread, Thread Oop address: [140,440,780,852,720], state:[1]
pthread_t :[0x70000c587000], is the [4] thread, Thread Oop address: [140,440,780,815,488], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
block!
===------------- ThreadTbalbolcek !-
---------------===
pthread_t :[0x70000c710000], is the [7] thread, Thread Oop address: [140,440,780,927,184], state:[1]
pthread_t :[0x70000c68d000], is the [6] thread, Thread Oop address: [140,440,780,889,952], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c60a000], is the [5] thread, Thread Oop address: [140,440,780,852,720], state:[1]
pthread_t :[0x70000c587000], is the [4] thread, Thread Oop address: [140,440,780,815,488], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
block!
===------------- ThreadTable ----------------===
pthread_t :[0x70000c793000], is the [8] thread, Thread Oop address: [140,440,780,964,416], state:[1]
pthread_t :[0x70000c816000], is the [9] thread, Thread Oop address: [140,440,781,001,648], state:[0]
pthread_t :[0x70000c710000], is the [7] thread, Thread Oop address: [140,440,780,927,184], state:[1]
pthread_t :[0x70000c68d000], is the [6] thread, Thread Oop address: [140,440,780,889,952], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c60a000], is the [5] thread, Thread Oop address: [140,440,780,852,720], state:[1]
pthread_t :[0x70000c587000], is the [4] thread, Thread Oop address: [140,440,780,815,488], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[0](main)
===------------------------------------------===
block!
block!
block!
===------------- ThreadTable ----------------===
pthread_t :[0x70000c899000], is the [10] thread, Thread Oop address: [140,440,781,038,880], state:[1]
pthread_t :[0x70000c793000], is the [8] thread, Thread Oop address: [140,440,780,964,416], state:[1]
pthread_t :[0x70000c816000], is the [9] thread, Thread Oop address: [140,440,781,001,648], state:[1]
pthread_t :[0x70000c710000], is the [7] thread, Thread Oop address: [140,440,780,927,184], state:[1]
pthread_t :[0x70000c68d000], is the [6] thread, Thread Oop address: [140,440,780,889,952], state:[1]
pthread_t :[0x70000c3fe000], is the [1] thread, Thread Oop address: [140,440,780,704,112], state:[1]
pthread_t :[0x70000c504000], is the [3] thread, Thread Oop address: [140,440,780,778,192], state:[1]
pthread_t :[0x70000c481000], is the [2] thread, Thread Oop address: [140,440,780,739,968], state:[1]
pthread_t :[0x70000c60a000], is the [5] thread, Thread Oop address: [140,440,780,852,720], state:[1]
pthread_t :[0x70000c587000], is the [4] thread, Thread Oop address: [140,440,780,815,488], state:[1]
pthread_t :[0x70000c37b000], is the [0] thread, Thread Oop address: [140,440,698,078,800], state:[1](main)
===------------------------------------------===
gc over!!
90                  // above is gc's output. I didn't delete it. From now on, it's the java program's output.
90
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class [[I
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class [[[I
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int
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void
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class java.lang.Void
Thread[Thread-0,5,main]
Thread[Thread-3,5,main]
Exception in thread "Thread-0" Thread[Thread-6,5,main]    // MultiThread's output will be chaos. It's normal.
java.lang.RuntimeExceptionThread[Thread-4,5,main]

Thread[Thread-7,5,main]
Thread[Thread-9,5,main]	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)

Thread[Thread-8,5,main]
Thread[Thread-2,5,main]
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)Thread[Thread-5,5,main]

Thread[Thread-1,5,main]
false	at java/lang/Throwable.<init>(Throwable.java:249)

	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
	at Test7.run(Test7.java:23)
Exception in thread "Thread-3" Exception in thread "Thread-6" Exception in thread "Thread-4" Exception in thread "Thread-7" Exception in thread "Thread-9" Exception in thread "Thread-8" Exception in thread "Thread-2" Exception in thread "Thread-5" Exception in thread "Thread-1" java.lang.RuntimeException
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:249)
	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
	at Test7.run(Test7.java:23)
java.lang.RuntimeException
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:249)
	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
	at Test7.run(Test7.java:23)
java.lang.RuntimeException
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:249)
	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
2.13909504E9
	at Test7.run(Test7.java:23)
true
java.lang.RuntimeException
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:249)
	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
	at Test7.run(Test7.java:23)
java.lang.RuntimeException
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:249)
	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
	at Test7.run(Test7.java:23)
java.lang.RuntimeException
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:249)
	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
	at Test7.run(Test7.java:23)
java.lang.RuntimeException
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:249)
	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
	at Test7.run(Test7.java:23)
java.lang.RuntimeException
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:249)
	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
	at Test7.run(Test7.java:23)
java.lang.RuntimeException
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:249)
	at java/lang/Exception.<init>(Exception.java:54)
	at java/lang/RuntimeException.<init>(RuntimeException.java:51)
	at Test7.run(Test7.java:23)
Exception in thread "main" java.io.FileNotFoundException: / (Is a directory)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:0)
	at java/lang/Throwable.fillInStackTrace(Throwable.java:781)
	at java/lang/Throwable.<init>(Throwable.java:264)
	at java/lang/Exception.<init>(Exception.java:66)
	at java/io/IOException.<init>(IOException.java:58)
	at java/io/FileNotFoundException.<init>(FileNotFoundException.java:64)
	at java/io/FileInputStream.open0(FileInputStream.java:0)
	at java/io/FileInputStream.open(FileInputStream.java:195)
	at java/io/FileInputStream.<init>(FileInputStream.java:123)
	at java/io/FileInputStream.<init>(FileInputStream.java:93)
	at Test7.main(Test7.java:37)

About Tests

Some Java test files, especially those for Java lambda expressions, were sourced from online examples.

Pitfalls and Areas for Improvement

  1. Improve the precision of NAN error messages.
  2. Enhance the clarity of exception messages.
  3. Add support for more complex lambda expressions.

Java Features Support

  • [x] Fully independent ClassFile parser tool support: @wind2412:javap
  • [x] Multithread support
  • [x] Exception handling support
  • [x] Some native libraries support
  • [x] Simple lambda support (via invokedynamic)
  • [x] Reflection support for most scenarios
  • [x] Stop-the-world and GC support using the GC-Root algorithm

Debugging Bytecode Execution

If you want to see detailed bytecode execution messages, modify the Makefile as follows:

CPP_FLAGS := -std=c++14 -O3 -DDEBUG -DKLASS_DEBUG -DPOOL_DEBUG -DSTRING_DEBUG

After recompiling, running the JVM will display detailed execution messages.

Example Code

// Test.java
class Test {
    public static void main(String[] args) {
        System.out.println("Today is a good day! On December 2nd, my JVM can print hello world~\n");
    }
}

Running the Code

Re-compile and run:

./bin/wind_jvm Test

Output Example

You will see detailed bytecode output and the execution result:

Hello, wind jvm!

hello world

This project was created during my undergraduate studies, around 2017–2018.

Thank you for playing with wind JVM! Though it’s simple, I hope you enjoy exploring it and find it helpful for learning about JVM internals.