线程hardy会一直等待下去么？ - 未名空间MITBBS历史存档

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线程hardy会一直等待下去么？

线程hardy会一直等待下去么？# Java - 爪哇娇娃

q*s2010-07-08 07:07

1 楼

代码见下面，为什么？
多谢各位！
public class TwoThreads {
static Thread laurel, hardy;
static final Object[] locker = new Object[0];
public static void main(String[] args) {
laurel = new Thread() {
public void run() {
System.out.println("A");
try {
hardy.sleep(1000);
} catch (Exception e) {
System.out.println("B");
}
System.out.println("C");
}

q*u2010-07-08 07:07

2 楼

hardy.sleep(1000); 等效于Thread.sleep(1000);　所以laurel 肯定先结束，最后两
个字母一定是CF
你这个程序是不是copy错了，locker在哪里

代码见下面，为什么？
多谢各位！
public class TwoThreads {
static Thread laurel, hardy;
static final Object[] locker = new Object[0];
public static void main(String[] args) {
laurel = new Thread() {
public void run() {
System.out.println("A");
try {
hardy.sleep(1000);
} catch (Exception e) {
System.

【在 q***s 的大作中提到】

: 代码见下面，为什么？
: 多谢各位！
: public class TwoThreads {
: static Thread laurel, hardy;
: static final Object[] locker = new Object[0];
: public static void main(String[] args) {
: laurel = new Thread() {
: public void run() {
: System.out.println("A");
: try {

m*t2010-07-08 07:07

3 楼

This is interesting. Something must have called laurel.notify() or notifyAll
()
for hardy to exit. I just don't understand what.

【在 q***s 的大作中提到】

q*s2010-07-08 07:07

4 楼

程序没有错，你说的结果也是对的，hardy并没有一直等下去。程序输出的结果为：ADCF。
本来我认为hardy会一直等下去的，因为那里有一个wait()，但是，结果没有。
但如果我把wait函数synchronized到另外一个对象上，比如那个locker，然后用locker.wait()来等待，则hardy会一直等下去。
哪位大侠能给解释一下，多谢！

【在 q*********u 的大作中提到】

: hardy.sleep(1000); 等效于Thread.sleep(1000);　所以laurel 肯定先结束，最后两
: 个字母一定是CF
: 你这个程序是不是copy错了，locker在哪里
:
: 代码见下面，为什么？
: 多谢各位！
: public class TwoThreads {
: static Thread laurel, hardy;
: static final Object[] locker = new Object[0];
: public static void main(String[] args) {

q*s2010-07-08 07:07

5 楼

这也是我不明白的地方，没有notify，wait是如何结束的？

notifyAll

【在 m******t 的大作中提到】

: This is interesting. Something must have called laurel.notify() or notifyAll
: ()
: for hardy to exit. I just don't understand what.

m*t2010-07-08 07:07

6 楼

Since you've tried locker and it doesn't happen there, it's possible
that this is thread implementation specific, i.e., when a thread is done
executing, some code calls notify() or more likely notifyAll().
I looked for that in Thread's source code but a lot of it is
native.

【在 q***s 的大作中提到】

: 这也是我不明白的地方，没有notify，wait是如何结束的？
:
: notifyAll

s*n2010-07-08 07:07

7 楼

very interesting. since spurious wakeups are always allowed for wait(), it
is not wrong that JVM decides to wake it up upon thread termination. this
cannot be a useful feature, nobody should sync on a thread object like you
did. probably for some historic reasons.

q*u2010-07-08 07:07

8 楼

其实是有这方面的应用的，比如
synchronized(this){
...
}
这种代码出现频率很高的。
看来如果是thread对象，　猜测那么jvm有这个特性，当线程结束，线程自己会自动
notify了

very interesting. since spurious wakeups are always allowed for wait(), it
is not wrong that JVM decides to wake it up upon thread termination. this
cannot be a useful feature, nobody should sync on a thread object like you
did. probably for some historic reasons.

【在 s******n 的大作中提到】

: very interesting. since spurious wakeups are always allowed for wait(), it
: is not wrong that JVM decides to wake it up upon thread termination. this
: cannot be a useful feature, nobody should sync on a thread object like you
: did. probably for some historic reasons.