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Fix 添加ArrayList扩容注释 #189

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Fix 添加ArrayList扩容注释 #189

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a482297
:twisted_rightwards_arrows: Merging branches. master
crossoverJie Mar 26, 2019
c08571c
添加ArrayList扩容注释
Kevin-Ban Oct 25, 2019
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2 changes: 1 addition & 1 deletion MD/Synchronize.md
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,7 @@ public class com.crossoverjie.synchronize.Synchronize {
#### 释放锁
当有另外一个线程获取这个锁时，持有偏向锁的线程就会释放锁，释放时会等待全局安全点(这一时刻没有字节码运行)，接着会暂停拥有偏向锁的线程，根据锁对象目前是否被锁来判定将对象头中的 `Mark Word` 设置为无锁或者是轻量锁状态。

偏向锁可以提高带有同步却没有竞争的程序性能，但如果程序中大多数锁都存在竞争时，那偏向锁就起不到太大作用。可以使用 `-XX:-userBiasedLocking=false` 来关闭偏向锁，并默认进入轻量锁。
偏向锁可以提高带有同步却没有竞争的程序性能，但如果程序中大多数锁都存在竞争时，那偏向锁就起不到太大作用。可以使用 `-XX:-UseBiasedLocking` 来关闭偏向锁，并默认进入轻量锁。


### 其他优化
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2 changes: 2 additions & 0 deletions docs/collections/ArrayList.md
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Expand Up @@ -41,6 +41,8 @@
private void grow(int minCapacity) {
// overflow-conscious code
int oldCapacity = elementData.length;
// 配置ArrayList的新容量，其中oldCapacity >> 1为右移运算，相当于oldCapacity除以2，不直接使用oldCapacity/2是因为在计算机中，位移运算比除法运算的运行效率更高
// ArrayList扩容之后是扩容之前的容量的1.5倍
int newCapacity = oldCapacity + (oldCapacity >> 1);
if (newCapacity - minCapacity < 0)
newCapacity = minCapacity;
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2 changes: 1 addition & 1 deletion docs/thread/Synchronize.md
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,7 @@ public class com.crossoverjie.synchronize.Synchronize {
#### 释放锁
当有另外一个线程获取这个锁时，持有偏向锁的线程就会释放锁，释放时会等待全局安全点(这一时刻没有字节码运行)，接着会暂停拥有偏向锁的线程，根据锁对象目前是否被锁来判定将对象头中的 `Mark Word` 设置为无锁或者是轻量锁状态。

偏向锁可以提高带有同步却没有竞争的程序性能，但如果程序中大多数锁都存在竞争时，那偏向锁就起不到太大作用。可以使用 `-XX:-userBiasedLocking=false` 来关闭偏向锁，并默认进入轻量锁。
偏向锁可以提高带有同步却没有竞争的程序性能，但如果程序中大多数锁都存在竞争时，那偏向锁就起不到太大作用。可以使用 `-XX:-UseBiasedLocking` 来关闭偏向锁，并默认进入轻量锁。


### 其他优化
Expand Down