java - 为什么在 JNI 中调用纤程会在 JVM 中引发 StackOverflow？

Question

我认为这也是一个难题。反正我想试试。

我实现了一个在 Java 中移植原生 boost fibers 的 JNI 迷你项目。

这是JNI接口(interface)

inline void execute(JNIEnv * env,jobject runnable,jmethodID mid){
 cout <<  " 31---"  << endl;
 env->CallVoidMethod(runnable, mid);
  cout <<  " 32---"  << endl;
}

/*
 * Class:     java_ext_concurrent_fiber_NativeFiber
 * Method:    run
 * Signature: (Ljava/lang/Runnable;)J
 */
JNIEXPORT void JNICALL Java_ext_concurrent_fiber_NativeFiber_run
  (JNIEnv * env, jclass clazz, jobject runnable){
cout <<  " 1---"  << endl;
   jclass cls = env->GetObjectClass( runnable);
   cout <<  " 2---"  << endl;
   jmethodID mid = env->GetMethodID( cls, "run", "()V");
cout <<  " 3---"  << endl;

env->CallVoidMethod(runnable, mid);
  boost::fibers::fiber fiber(execute,env,runnable,mid);

  cout <<  " 3---"  << endl;

  }

这是java测试

public class Test {
    public static void main(String[] args) throws InterruptedException {

        NativeFiber fiber=new NativeFiber(new Runnable() {
            @Override
            public void run() {


                System.out.println("hello");
            }
        });
        fiber.start();


    }
}

如果我执行这段代码

throws StackOverflowException

如果我删除 fiber.join() 并添加 fiber.detach();

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00007f5a37017f1f, pid=16559, tid=0x00007f5a38522700
#
# JRE version: Java(TM) SE Runtime Environment (8.0_131-b11) (build 1.8.0_131-b11)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.131-b11 mixed mode linux-amd64 compressed oops)
# Problematic frame:
# V  [libjvm.so+0x6d7f1f]  jni_CallVoidMethodV+0x3f
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /data/git/concurrent/hs_err_pid16559.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp

Answer 1

可能是因为 Fibers 栈对于 Java 来说太小了。

但是，在没有明确支持的情况下在纤程上运行 JVM/JRE 代码确实是不明智的。

If you have uncovered a part of the JVM specification that explicitly allows it, and you know that the parts of the JRE that you depend on all are safe for use on fibers, you can obviously disregard these words of caution

碰巧的是，JVM/JRE 可能包含任意数量的基于线程模型的假设。例如使用线程本地静态实例对于非同步访问是安全的。这将打破假设并因此导致未指定的行为。

如果您需要纤程，请查看 JVM 支持的方法来实现它们(我无法想象没有流行的库可以做到这一点)。