kongkong的专栏

test1函数int test1(int a, int b) { return a + b;}汇编00A83CE3 mov eax,dword ptr [b] 00A83CE6 push eax 00A83CE7 mov ecx,dword ptr [a] 00A83CEA push ecx 00A83CEB call test1 (0A811DBh) 00A83CF0 add

ClassClass.forNamepublic static Class<?> forName(String name, boolean initialize, ClassLoader loader) throws ClassNotFoundException { Class<?> caller = null; SecurityManager sm =

初始_tenuring_thresholdproduct(uintx, MaxTenuringThreshold, 15, \ "Maximum value for tenuring threshold")DefNewGenerationDefNewGeneration::DefNewGeneration(ReservedSpace rs, si

save_marks()为_saved_mark_word变量赋值为碰撞指针的_top的值genCollectedHeap.cppsave_marks()genCollectedHeap.cpp:480 调用GenCollectedHeap::save_marks()openjdk12void GenCollectedHeap::save_marks() { _young_gen->save_marks(); _old_gen->save_marks();}openj

copy_to_survivor_spacedefNewGeneration.cpp784copy_to_survivor_spaceoop DefNewGeneration::copy_to_survivor_space(oop old) { assert(is_in_reserved(old) && !old->is_forwarded(), "shouldn't be scavenging this oop"); size_t s = old-&

常见写法jvm源码有很多这种类型写法的代码MutexLocker ml(Heap_lock);ObjectWaiter node(Self);等这里以MutexLocker举例MutexLocker ml(Heap_lock);MutexLockerclass MutexLocker: StackObj { private: Monitor * _mutex; public: MutexLocker(Monitor * mutex) { // MutexLocker ml(He

DefNewGeneration::collectvoid DefNewGeneration::collect(bool full, bool clear_all_soft_refs, // todo soft size_t size, bool is_tlab) { ...... /

ASM Bytecode Outline使用选择类 -> Code -> Show Bytecode outlinejclasslibView -> Show Bytecode With Jclasslib

InstanceKlassallocate_instance_klassInstanceKlass* InstanceKlass::allocate_instance_klass( ClassLoaderData* loader_data, int vtable_len,

场景1i++public int increment1() { int i = 0; i++; return i;}字节码0 iconst_01 istore_12 iinc 1 by 15 iload_16 ireturn++ipublic int increment2() { int i = 0; ++i; return i;}字节码0 iconst_01 istore_12 iinc 1 by 15 iload_1

MemoryTypeenum MemoryType { // Memory type by sub systems. It occupies lower byte. mtJavaHeap = 0x00, // Java heap java堆 mtClass = 0x01, // memory class for Java classes mtThread = 0x02, // memory for thread obje

基本类型typedef signed char jbyte;typedef int jint;typedef jint jsize;typedef long jlong;typedef unsigned char jboolean;typedef unsigned short jchar;typedef short jshort;typedef float jfloat;typedef double j

堆内存分配genCollectedHeap.cpp:334HeapWord* GenCollectedHeap::mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded) { return collector_policy()->mem_allocate_work(size, false /* is_tlab */, gc_overhead_limit_was_exceeded); // 根据策略来分配

//// Created by kongqi on 2021-11-24.//#include "mythreadsignal.h"#include<pthread.h>#include <iostream>#include<unistd.h>#include <iostream>using namespace std;pthread_mutex_t mutexm2 = PTHREAD_MUTEX_INITIALIZER;/*初始化互斥

Atomic::xchg替换把exchange_value的值，存到*dest去可以理解 dest = exchange_value (当然这个操作有可能会失败)返回的是原值，也就是最初的dest的值inline int Atomic::xchg (int exchange_value, volatile int* dest) { __asm__ volatile ( "xchgl (%2),%0" : "=r" (exchange_value)

park()void Parker::park(bool isAbsolute, jlong time) { // Ideally we'd do something useful while spinning, such 理想情况下，我们会在旋转时做一些有用的事情，例如 // as calling unpackTime(). 作为调用 unpackTime() // Optional fast-path check: 可选的快速路径检查： // Return immediatel

InstanceKlass::link_class_implvtable和itable是在链接阶段初始化if (!this_oop()->is_shared()) { ResourceMark rm(THREAD); klassVtable* kv = this_oop->vtable(); // 初始化vtable kv->initialize_vtable(true, CHECK_false); klassItable* ki = this_oop->

基础数据INamepublic interface IName { public String getName();}AApublic class AA implements IName{ @Override public String getName() { return "AA"; } public static void staticFun(){ System.out.println(); }}Main

初始数据AApublic class AA { public static final int PAGE = 20; private int num = 10; public void name(){ System.out.println("AA"); } public void add() { }}BBpublic class BB extends AA{ public void name(){

symbol.hppclass ClassLoaderData;// We separate the fields in SymbolBase from Symbol::_body so that// Symbol::size(int) can correctly calculate the space needed.class SymbolBase : public MetaspaceObj { public: ATOMIC_SHORT_PAIR( volatile short _

consolewindows菜单下的consoleuniversescanoops扫描指定内存区间，类的类型scanoops 0x000000076b180000 0x000000076fc00000 java.lang.Stringinspect查看某个类的信息

结构图 本图来自揭秘Java虚拟机(JVM设计原理与实现)数据存放源码putvoid slot_at_put(int which, CPSlot s) const { assert(is_within_bounds(which), "index out of bounds"); assert(s.value() != 0, "Caught something"); *(intptr_t*)&base()[which] = s.val

thread.cppis_lock_ownedbool Thread::is_lock_owned(address adr) const { return on_local_stack(adr);}thread.hppon_local_stackbool on_local_stack(address adr) const { // 在（_stack_base-_stack_size） 和 _stack_base 之间 /* QQQ this has knowledge o

getDeclaredMethodspublicOnly = falsepublic Method[] getDeclaredMethods() throws SecurityException { checkMemberAccess(Member.DECLARED, Reflection.getCallerClass(), true); return copyMethods(privateGetDeclaredMethods(false)); }getMet

例子1从指令看出new String(“hello1”)，这个创建了2个对象public void anew(){ String str = new String("hello1");}指令 0 new #14 <java/lang/String> // 第2个对象 3 dup 4 ldc #15 <hello1> // 第1个对象 6 invokespecial #16 <java/lang/String.<init>>

defNewGeneration.hppclass DefNewGeneration: public Generation {.................}defNewGeneration.cpp构造函数DefNewGeneration::DefNewGeneration(ReservedSpace rs, size_t initial_size,

https://blog.youkuaiyun.com/w57685321/article/details/106326558/

编译jdksudo bash configure --with-debug-level=slowdebug --with-target-bits=64 --disable-warnings-as-errors --enable-dtrace --with-jvm-variants=server参数说明--with-boot-jdk：指定Bootstrap JDK路径--with-debug-level：编译级别,可选值为release、fastdebug、slowdebug和optimized,默

demoGetClassDemo demo = new GetClassDemo();Class clazz = demo.getClass(); // 初始化的classSystem.out.println("clazz="+clazz);Objectnative方法public final native Class<?> getClass();openjdk8\jdk\src\share\native\java\lang\Object.cJNIEXPORT jclass

make_localopenjdk8\hotspot\src\share\vm\runtime\jniHandles.cppjobject JNIHandles::make_local(JNIEnv* env, oop obj) { if (obj == NULL) { return NULL; // ignore null handles } else { JavaThread* thread = JavaThread::thread_from_j

pthread_getpecific和pthread_setspecific是实现同一个线程中不同函数间共享数据的一种很好的方式#include <pthread.h>int pthread_setspecific(pthread_key_t key, const void *value);void *pthread_getspecific(pthread_key_t key);os::thread_local_storage_at_puthotspot\src\os\linux\

SymbolTable::new_symbolsopenjdk8\hotspot\src\share\vm\classfile\symbolTable.hppstatic void new_symbols(ClassLoaderData* loader_data, constantPoolHandle cp, int names_count, const char** name, int* lengt

HandleArea::allocate_handleopenjdk8\hotspot\src\share\vm\runtime\handles.cpp调用的是real_allocate_handle(obj)oop* HandleArea::allocate_handle(oop obj) { assert(_handle_mark_nesting > 1, "memory leak: allocating handle outside HandleMark"); assert(_no

Symbol::Symbol(symbol.cppSymbol::Symbol(const u1* name, int length, int refcount) { _refcount = refcount; //引用数量 _length = length; // 长度 _identity_hash = os::random(); //hash for (int i = 0; i < _length; i++) { byte_at_put(i, name[i]); //

前言以JDK8为例来分析String.javapublic native String intern();String.copenjdk8\openjdk\jdk\src\share\native\java\lang\String.c#include "jvm.h"#include "java_lang_String.h"JNIEXPORT jobject JNICALLJava_java_lang_String_intern(JNIEnv *env, job.

https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-6.html

TheCodeAttributeTheCodeattribute is a variable-length attribute in theattributestable of amethod_infostructure (§4.6). ACodeattribute contains the Java Virtual Machine instructions and auxiliary information for a method, including an instance i...

AttributesAttributesare used in theClassFile,field_info,method_info, andCode_attributestructures of theclassfile format (§4.1,§4.5,§4.6,§4.7.3).All attributes have the following general format:attribute_info { u2 attribute_name_inde...

MethodsEach method, including each instance initialization method (§2.9) and the class or interface initialization method (§2.9), is described by amethod_infostructure.No two methods in oneclassfile may have the same name and descriptor (§4.3.3)...

Each field is described by afield_infostructure.No two fields in oneclassfile may have the same name and descriptor (§4.3.2).The structure has the following format:field_info { u2 access_flags; u2 name_index; ...