1.8以下的版本才有該問題颅夺，在1.8已經(jīng)解決該問題天吓。
擴(kuò)容調(diào)用transfer
void resize(int newCapacity) {
Entry[] oldTable = table;
int oldCapacity = oldTable.length;
if (oldCapacity == MAXIMUM_CAPACITY) {
threshold = Integer.MAX_VALUE;
return;
}
Entry[] newTable = new Entry[newCapacity];
// 下面這行重點(diǎn)
transfer(newTable, initHashSeedAsNeeded(newCapacity));
table = newTable;
threshold = (int)Math.min(newCapacity * loadFactor, MAXIMUM_CAPACITY + 1);
}
transfer方法
/**
* Transfers all entries from current table to newTable.
*/
void transfer(Entry[] newTable, boolean rehash) {
int newCapacity = newTable.length;
for (Entry<K,V> e : table) {
while(null != e) {
// 這行也是重點(diǎn)
Entry<K,V> next = e.next;
if (rehash) {
e.hash = null == e.key ? 0 : hash(e.key);
}
int i = indexFor(e.hash, newCapacity);
// 重點(diǎn)這三行
e.next = newTable[i];
newTable[i] = e;
e = next;
}
}
}
我們假設(shè)Map中有個(gè)table[i]如下鏈表:
graph TD
A-->B
這個(gè)時(shí)候有兩個(gè)個(gè)線程要進(jìn)程擴(kuò)容分別為T1,T2
image.png
