![\"\u4e3b\u5185\u5b58\uff0c\u7ebf\u7a0b\uff0c\u5de5\u4f5c\u5185\u5b58\u5173\u7cfb\u56fe\"](\"..\/..\/upload\/2019_07\/190713095496011.png\")
<\/p>Java\u5185\u5b58\u6a21\u578b\u7684\u4e3b\u8981\u76ee\u6807\u662f\u5b9a\u4e49\u7a0b\u5e8f\u4e2d\u5404\u4e2a\u53d8\u91cf\u7684\u8bbf\u95ee\u89c4\u5219\uff0c\u5373\u5728\u865a\u62df\u673a\u4e2d\u5c06\u53d8\u91cf\u5b58\u50a8\u5230\u5185\u5b58\u548c\u5728\u5185\u5b58\u4e2d\u53d6\u51fa\u53d8\u91cf\u7684\u5e95\u5c42\u7ec6\u8282\uff0c\u662f\u56f4\u7ed5\u7740\u5728\u5e76\u53d1\u8fc7\u7a0b\u4e2d\u5982\u4f55\u5904\u7406\u539f\u5b50\u6027\uff0c\u53ef\u89c1\u6027\u548c\u6709\u5e8f\u6027\u8fd93\u4e2a\u7279\u6027\u5efa\u7acb\u7684<\/p>
<\/p>
\u5b9a\u4e49\u4e00\u4e2a\u9759\u6001\u53d8\u91cf:static int a = 1;
\u7ebf\u7a0bA\u5de5\u4f5c\u5185\u5b58 | \u6307\u5411 | \u4e3b\u5185\u5b58 | \u64cd\u4f5c
-- | -- | -- | --
-- | -- | a = 1 | --
a = 1 | <-- | a = 1 | \u7ebf\u7a0bA\u62f7\u8d1d\u4e3b\u5185\u5b58\u53d8\u91cf\u526f\u672c
a = 3 | -- | a = 1 | \u7ebf\u7a0bA\u4fee\u6539\u5de5\u4f5c\u5185\u5b58\u53d8\u91cf\u503c
a = 3 | --> | a = 3 | \u7ebf\u7a0bA\u5de5\u4f5c\u5185\u5b58\u53d8\u91cf\u5b58\u50a8\u5230\u4e3b\u5185\u5b58\u53d8\u91cf<\/p>
\u4e0a\u9762\u7684\u4e00\u7cfb\u5217\u5185\u5b58\u64cd\u4f5c\uff0c\u5728JMM\u4e2d\u5b9a\u4e49\u4e868\u79cd\u64cd\u4f5c\u6765\u5b8c\u6210<\/p>
\u4e3b\u5185\u5b58\u548c\u5de5\u4f5c\u5185\u5b58\u4e4b\u95f4\u7684\u4ea4\u4e92\uff0cJMM\u5b9a\u4e49\u4e868\u79cd\u64cd\u4f5c\u6765\u5b8c\u6210\uff0c\u6bcf\u4e2a\u64cd\u4f5c\u90fd\u662f\u539f\u5b50\u6027\u7684<\/p>
\u5f53\u5f15\u5165\u7ebf\u7a0bB\u7684\u65f6\u5019
\u5b9a\u4e49\u4e00\u4e2a\u9759\u6001\u53d8\u91cf:static int a = 1;
\u64cd\u4f5c\u987a\u5e8f | \u7ebf\u7a0bA\u5de5\u4f5c\u5185\u5b58 | \u7ebf\u7a0bB\u5de5\u4f5c\u5185\u5b58 | \u6307\u5411 | \u4e3b\u5185\u5b58 | \u64cd\u4f5c
-- | -- | -- | -- | -- | --
-- | -- | -- | -- | a = 1 | --
1 | a = 1 | -- | <-- | a = 1 | \u7ebf\u7a0bA\u62f7\u8d1d\u4e3b\u5185\u5b58\u53d8\u91cf\u526f\u672c
2 | a = 3 | -- | -- | a = 1 | \u7ebf\u7a0bA\u4fee\u6539\u5de5\u4f5c\u5185\u5b58\u53d8\u91cf\u503c
3 | a = 3 | -- | --> | a = 1 | \u7ebf\u7a0bA\u5de5\u4f5c\u5185\u5b58\u53d8\u91cf\u5b58\u50a8\u5230\u4e3b\u5185\u5b58\u53d8\u91cf\uff0c\u4e3b\u5185\u5b58\u53d8\u91cf\u8fd8\u672a\u66f4\u65b0
4.1 | a = 3 | a = 1 | <-- | a = 3 |\u7ebf\u7a0bB\u62f7\u8d1d\u4e3b\u5185\u5b58\u53d8\u91cf\u526f\u672c\u968f\u540e\u4e3b\u5185\u5b58\u53d8\u91cf\u66f4\u65b0\u7ebf\u7a0bA\u5de5\u4f5c\u5185\u5b58\u53d8\u91cf
4.2 | a = 3 | a = 1 | <-- | a = 3 |\u7ebf\u7a0bA\u5de5\u4f5c\u5185\u5b58\u53d8\u91cf\u5b58\u50a8\u5230\u4e3b\u5185\u5b58\u53d8\u91cf\u968f\u540e\u7ebf\u7a0bB\u83b7\u53d6\u4e3b\u5185\u5b58\u53d8\u91cf\u526f\u672c
\u64cd\u4f5c4\u7684\u65f6\u5019\u53ef\u80fd\u51fa\u73b0\uff1a1.\u7ebf\u7a0bA\u53d8\u91cf\u503c\u8fd8\u672a\u4fdd\u5b58\u5230\u4e3b\u5185\u5b58\u53d8\u91cf\uff0c2.\u7ebf\u7a0bA\u53d8\u91cf\u503c\u4fdd\u5b58\u5230\u4e3b\u5185\u5b58\u53d8\u91cf\u3002\u4f7f\u7528volatile\u5173\u952e\u5b57\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898<\/p>
\u4fee\u6539\u5185\u5b58\u53d8\u91cf\u540e\u7acb\u523b\u540c\u6b65\u5230\u4e3b\u5185\u5b58\u4e2d\uff0c\u5176\u4ed6\u7684\u7ebf\u7a0b\u7acb\u523b\u5f97\u77e5\u5f97\u76ca\u4e8eJava\u7684\u5148\u884c\u53d1\u751f\u539f\u5219<\/strong><\/p> \u5148\u884c\u53d1\u751f\u539f\u5219\u4e2d\u7684volatile\u539f\u5219\uff1a\u4e00\u4e2avolatile\u53d8\u91cf\u7684\u5199\u64cd\u4f5c\u5148\u884c\u4e8e\u540e\u9762\u53d1\u751f\u7684\u8fd9\u4e2a\u53d8\u91cf\u7684\u8bfb\u64cd\u4f5c\uff0c\u65f6\u95f4\u987a\u5e8f<\/p> \u5b9a\u4e49\u4e00\u4e2a\u9759\u6001\u53d8\u91cf:static int a = 1; \u6307\u4ee4\u91cd\u6392\u5e8f:JVM\u5728\u7f16\u8bd1Java\u4ee3\u7801\u7684\u65f6\u5019\u6216\u8005CPU\u5728\u6267\u884cJVM\u5b57\u8282\u7801\u7684\u65f6\u5019\uff0c\u5bf9\u73b0\u6709\u7684\u6307\u4ee4\u8fdb\u884c\u91cd\u65b0\u6392\u5e8f\uff0c\u76ee\u7684\u662f\u4e3a\u4e86\u518d\u4e0d\u5f71\u54cd\u6700\u7ec8\u7ed3\u679c\u7684\u524d\u63d0\u4e0b\uff0c\u4f18\u5316\u7a0b\u5e8f\u7684\u6267\u884c\u6548\u7387<\/p> \u5185\u5b58\u5c4f\u969c:\u4e00\u79cd\u5c4f\u969c\u6307\u4ee4\uff0c\u8ba9CPU\u6216\u6bd4\u7f16\u8bd1\u5668\u5bf9\u5c4f\u853d\u6307\u4ee4\u4e4b\u524d\u548c\u4e4b\u540e\u53d1\u51fa\u7684\u5185\u5b58\u64cd\u4f5c\u6267\u884c\u4e00\u4e2a\u6392\u5e8f\u7ea6\u675f\u3002 \u8fd9\u6bb5\u4ee3\u7801\u7684\u7ed3\u679c\u6709\u53ef\u80fd\u4e0d\u662f100000\uff0c\u6709\u53ef\u80fd\u5c0f\u4e8e100000\u3002 \u4e00\u4e2a\u64cd\u4f5c\u662f\u4e0d\u53ef\u4e2d\u65ad\u7684\u3002\u5373\u4f7f\u662f\u5728\u591a\u4e2a\u7ebf\u7a0b\u4e00\u8d77\u6267\u884c\u7684\u65f6\u5019\uff0c\u4e00\u4e2a\u64cd\u4f5c\u4e00\u65e6\u5f00\u59cb\uff0c\u5c31\u4e0d\u4f1a\u88ab\u5176\u5b83\u7ebf\u7a0b\u5e72\u6270<\/p> \u5f53\u4e00\u4e2a\u7ebf\u7a0b\u4fee\u6539\u4e86\u5171\u4eab\u53d8\u91cf\u7684\u503c\uff0c\u5176\u4ed6\u7ebf\u7a0b\u7acb\u5373\u53ef\u77e5<\/p> \u7a0b\u5e8f\u6267\u884c\u7684\u987a\u5e8f\u6309\u7167\u4ee3\u7801\u7684\u5148\u540e\u987a\u5e8f\u6267\u884c\uff0c\u5728Java\u5185\u5b58\u6a21\u578b\u4e2d\uff0c\u5141\u8bb8\u7f16\u8bd1\u5668\u548c\u5904\u7406\u5668\u5bf9\u6307\u4ee4\u8fdb\u884c\u91cd\u6392\u5e8f\uff0c\u4f46\u662f\u91cd\u6392\u5e8f\u8fc7\u7a0b\u4e0d\u4f1a\u5f71\u54cd\u5230\u5355\u7ebf\u7a0b\u7a0b\u5e8f\u7684\u6267\u884c\uff0c\u5374\u4f1a\u5f71\u54cd\u5230\u591a\u7ebf\u7a0b\u5e76\u53d1\u6267\u884c\u7684\u6b63\u786e\u6027<\/p> JMM\u4e2d\u4e24\u9879\u64cd\u4f5c\u4e4b\u95f4\u7684\u504f\u5e8f\u5173\u7cfb\uff0c\u5982\u679c\u64cd\u4f5cA\u53d1\u751f\u4e8e\u64cd\u4f5cB\u4e4b\u524d\uff0c\u64cd\u4f5cA\u53d1\u751f\u7684\u5f71\u54cd\u53ef\u4ee5\u88ab\u64cd\u4f5cB\u89c2\u5bdf\u5230<\/p> \u5355\u7ebf\u7a0b\u548c\u6b63\u786e\u540c\u6b65\u7684\u591a\u7ebf\u7a0b\u7684\u6267\u884c\u7ed3\u679c\u4e0d\u4f1a\u88ab\u6539\u53d8<\/p> \u5982\u679c\u4e24\u4e2a\u64cd\u4f5c\u4e0d\u5728\u4e0b\u5217\u89c4\u5219\u4e2d\uff0c\u865a\u62df\u673a\u53ef\u4ee5\u5bf9\u5176\u91cd\u6392\u5e8f<\/p>
\u7ebf\u7a0bA\u5de5\u4f5c\u5185\u5b58 | \u7ebf\u7a0bB\u5de5\u4f5c\u5185\u5b58 | \u6307\u5411 | \u4e3b\u5185\u5b58 | \u64cd\u4f5c
-- | -- | -- | -- | --
-- | -- | -- | a = 1 | --
a = 1 | -- | <-- | a = 1 | \u7ebf\u7a0bA\u62f7\u8d1d\u4e3b\u5185\u5b58\u53d8\u91cf\u526f\u672c
a = 3 | -- | -- | a = 1 | \u7ebf\u7a0bA\u4fee\u6539\u5de5\u4f5c\u5185\u5b58\u53d8\u91cf\u503c
a = 3 | -- | --> | a = 1 | \u7ebf\u7a0bA\u5de5\u4f5c\u5185\u5b58\u53d8\u91cf\u5b58\u50a8\u5230\u4e3b\u5185\u5b58\u53d8\u91cf
a = 3 | a = 3 | <-- | a = 3 | volatile\u539f\u5219:\u4e3b\u5185\u5b58\u53d8\u91cf\u4fdd\u5b58\u7ebf\u7a0bA\u5de5\u4f5c\u5185\u5b58\u53d8\u91cf\u64cd\u4f5c\u5728\u7ebf\u7a0bB\u5de5\u4f5c\u5185\u5b58\u8bfb\u53d6\u4e3b\u5185\u5b58\u53d8\u91cf\u64cd\u4f5c\u4e4b\u524d<\/p>
\u7f16\u8bd1\u5668\u5728\u751f\u6210\u5b57\u8282\u7801\u65f6\uff0c\u4f1a\u5728\u6307\u4ee4\u5e8f\u5217\u4e2d\u63d2\u5165\u5185\u5b58\u5c4f\u969c\u6765\u7981\u6b62\u7279\u5b9a\u7c7b\u578b\u7684\u5904\u7406\u5668\u91cd\u6392\u5e8f\u3002<\/p>
\u56e0\u4e3anum++\u4e0d\u662f\u539f\u5b50\u64cd\u4f5c<\/p>