![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2025\/12\/1766479682-image-1024x636.png\")
<\/figure>\n\n\n\n\u5982\u56fe\u6240\u793a\u662f\u7ee7\u627f\u4e86\u4e0a\u9762\u7684\u4e1c\u897f\uff0c\u4ee5\u81ea\u4e0a\u800c\u4e0b\u7684\u65b9\u5f0f\uff0c\u5148\u5206\u6790\u4e00\u6ce2 Queue \u63a5\u53e3\u91cc\u90fd\u5b9a\u4e49\u4e86\u54ea\u4e9b\u65b9\u6cd5<\/p>\n\n\n\n
\/\/ \u5982\u679c\u961f\u5217\u5bb9\u91cf\u5141\u8bb8\uff0c\u7acb\u5373\u5c06\u5143\u7d20\u63d2\u5165\u961f\u5217\uff0c\u6210\u529f\u540e\u8fd4\u56de\n\/\/ \ud83c\udf1f\u5982\u679c\u961f\u5217\u5bb9\u91cf\u5df2\u6ee1\uff0c\u5219\u629b\u51fa\u5f02\u5e38\nboolean add(E e);\n\n\/\/ \u5982\u679c\u961f\u5217\u5bb9\u91cf\u5141\u8bb8\uff0c\u7acb\u5373\u5c06\u5143\u7d20\u63d2\u5165\u961f\u5217\uff0c\u6210\u529f\u540e\u8fd4\u56de\n\/\/ \ud83c\udf1f\u5982\u679c\u961f\u5217\u5bb9\u91cf\u5df2\u6ee1\uff0c\u5219\u8fd4\u56de false\n\/\/ \u5f53\u4f7f\u7528\u6709\u754c\u961f\u5217\u65f6\uff0coffer \u6bd4 add \u65b9\u6cd5\u66f4\u4f55\u65f6\nboolean offer(E e);\n\n\/\/ \u68c0\u7d22\u5e76\u5220\u9664\u961f\u5217\u7684\u5934\u8282\u70b9\uff0c\u8fd4\u56de\u503c\u4e3a\u5220\u9664\u7684\u961f\u5217\u5934\u8282\u70b9\n\/\/ \ud83c\udf1f\u5982\u679c\u961f\u5217\u4e3a\u7a7a\u5219\u629b\u51fa\u5f02\u5e38\nE remove();\n\n\/\/ \u68c0\u7d22\u5e76\u5220\u9664\u961f\u5217\u7684\u5934\u8282\u70b9\uff0c\u8fd4\u56de\u503c\u4e3a\u5220\u9664\u7684\u961f\u5217\u5934\u8282\u70b9\n\/\/ \ud83c\udf1f\u5982\u679c\u961f\u5217\u4e3a\u7a7a\u5219\u8fd4\u56de null\nE poll();\n\n\/\/ \u68c0\u67e5\u4f46\u4e0d\u5220\u9664\u961f\u5217\u5934\u8282\u70b9\n\/\/ \ud83c\udf1f\u5982\u679c\u961f\u5217\u4e3a\u7a7a\u5219\u629b\u51fa\u5f02\u5e38\nE element();\n\n\/\/ \u68c0\u67e5\u4f46\u4e0d\u5220\u9664\u961f\u5217\u5934\u8282\u70b9\n\/\/ \ud83c\udf1f\u5982\u679c\u961f\u5217\u4e3a\u7a7a\u5219\u8fd4\u56de null\nE peek();<\/code><\/pre>\n\n\n\nQueue \u63a5\u53e3\u7684\u65b9\u6cd5\uff0c\u5206\u4e3a\u4e09\u4e2a\u5927\u7c7b\uff1a<\/p>\n\n\n\n
\n- \u65b0\u589e\u5143\u7d20\u5230\u961f\u5217\u5bb9\u5668\u4e2d\uff1aadd\u3001offer<\/li>\n\n\n\n
- \u4ece\u961f\u5217\u5bb9\u5668\u4e2d\u79fb\u9664\u5143\u7d20\uff1aremove\u3001poll<\/li>\n\n\n\n
- \u67e5\u8be2\u961f\u5217\u5934\u8282\u70b9\u662f\u5426\u4e3a\u7a7a\uff1aelement\u3001peek<\/li>\n<\/ol>\n\n\n\n
BlockingQueue \u63a5\u53e3\u7ee7\u627f\u81ea Queue \u63a5\u53e3\uff0c\u6240\u4ee5\u6709\u4e9b\u8bed\u4e49\u76f8\u540c\u7684 API \u63a5\u53e3\u5c31\u6ca1\u6709\u653e\u4e0a\u6765\u89e3\u8bfb<\/p>\n\n\n\n
\/\/ \u5c06\u6307\u5b9a\u5143\u7d20\u63d2\u5165\u961f\u5217\uff0c\u5982\u679c\u961f\u5217\u5df2\u6ee1\uff0c\u7b49\u5f85\u76f4\u5230\u6709\u7a7a\u95f4\u53ef\u7528\uff1b\u901a\u8fc7 throws \u5f02\u5e38\u5f97\u77e5\uff0c\u53ef\u5728\u7b49\u5f85\u65f6\u6253\u65ad<\/em>
\/\/ \ud83c\udf1f\u76f8\u5bf9\u4e8e Queue \u63a5\u53e3\u800c\u8a00\uff0c\u662f\u4e00\u4e2a\u5168\u65b0\u7684\u65b9\u6cd5<\/em>
void<\/strong> put<\/strong>(E e) throws<\/strong> InterruptedException;
\/\/ \u5c06\u6307\u5b9a\u5143\u7d20\u63d2\u5165\u961f\u5217\uff0c\u5982\u679c\u961f\u5217\u5df2\u6ee1\uff0c\u5728\u7b49\u5f85\u6307\u5b9a\u7684\u65f6\u95f4\u5185\u7b49\u5f85\u817e\u51fa\u7a7a\u95f4\uff1b\u901a\u8fc7 throws \u5f02\u5e38\u5f97\u77e5\uff0c\u53ef\u5728\u7b49\u5f85\u65f6\u6253\u65ad<\/em>
\/\/ \ud83c\udf1f\u76f8\u5f53\u4e8e\u662f offer(E e) \u7684\u6269\u5c55\u65b9\u6cd5<\/em>
boolean<\/strong> offer<\/strong>(E e, long<\/strong> timeout, TimeUnit unit) throws<\/strong> InterruptedException;
\/\/ \u68c0\u7d22\u5e76\u9664\u53bb\u6b64\u961f\u5217\u7684\u5934\u8282\u70b9\uff0c\u5982\u6709\u5fc5\u8981\uff0c\u7b49\u5f85\u76f4\u5230\u5143\u7d20\u53ef\u7528\uff1b\u901a\u8fc7 throws \u5f02\u5e38\u5f97\u77e5\uff0c\u53ef\u5728\u7b49\u5f85\u65f6\u6253\u65ad<\/em>
E take<\/strong>() throws<\/strong> InterruptedException;
\/\/ \u68c0\u7d22\u5e76\u5220\u9664\u6b64\u961f\u5217\u7684\u5934\uff0c\u5982\u679c\u6709\u5fc5\u8981\u4f7f\u5143\u7d20\u53ef\u7528\uff0c\u5219\u7b49\u5f85\u6307\u5b9a\u7684\u7b49\u5f85\u65f6\u95f4\uff1b\u901a\u8fc7 throws \u5f02\u5e38\u5f97\u77e5\uff0c\u53ef\u5728\u7b49\u5f85\u65f6\u6253\u65ad<\/em>
\/\/ \ud83c\udf1f\u76f8\u5f53\u4e8e\u662f poll() \u7684\u6269\u5c55\u65b9\u6cd5<\/em>
E poll<\/strong>(long<\/strong> timeout, TimeUnit unit) throws<\/strong> InterruptedException;
\/\/ \u8fd4\u56de\u961f\u5217\u5269\u4f59\u5bb9\u91cf\uff0c\u5982\u679c\u4e3a\u65e0\u754c\u961f\u5217\uff0c\u8fd4\u56de Integer.MAX_VALUE<\/em>
int<\/strong> remainingCapacity<\/strong>();
\/\/ \u5982\u679c\u6b64\u961f\u5217\u5305\u542b\u6307\u5b9a\u7684\u5143\u7d20\uff0c\u5219\u8fd4\u56de true<\/em>
public<\/strong> boolean<\/strong> contains<\/strong>(Object o);
\/\/ \u4ece\u6b64\u961f\u5217\u4e2d\u5220\u9664\u6240\u6709\u53ef\u7528\u5143\u7d20\uff0c\u5e76\u5c06\u5b83\u4eec\u6dfb\u52a0\u5230\u7ed9\u5b9a\u7684\u96c6\u5408\u4e2d<\/em>
int<\/strong> drainTo<\/strong>(Collection<? super<\/strong> E> c);
\/\/ \u4ece\u6b64\u961f\u5217\u4e2d\u6700\u591a\u79fb\u9664\u7ed9\u5b9a\u6570\u91cf\u7684\u53ef\u7528\u5143\u7d20\uff0c\u5e76\u5c06\u5b83\u4eec\u6dfb\u52a0\u5230\u7ed9\u5b9a\u7684\u96c6\u5408\u4e2d<\/em>
int<\/strong> drainTo<\/strong>(Collection<? super<\/strong> E> c, int<\/strong> maxElements);<\/code><\/pre>\n\n\n\n\u53ef\u4ee5\u770b\u5230 BlockingQueue \u63a5\u53e3\u4e2d\u4e2a\u6027\u5316\u7684\u65b9\u6cd5\u8fd8\u662f\u633a\u591a\u7684\u3002<\/p>\n\n\n\n
\u518d\u770b LinkedBlockingQueue \u7684\u6e90\u7801\uff1b\u4e3a\u4e86\u4fdd\u8bc1\u5e76\u53d1\u6dfb\u52a0\u3001\u79fb\u9664\u7b49\u64cd\u4f5c\uff0c\u4f7f\u7528\u4e86 JUC \u5305\u4e0b\u7684 ReentrantLock\u3001Condition \u63a7\u5236<\/p>\n\n\n\n
\/\/\u00a0take,\u00a0poll\u00a0\u7b49\u79fb\u9664\u64cd\u4f5c\u9700\u8981\u6301\u6709\u7684\u9501<\/em>\nprivate<\/strong>\u00a0final<\/strong>\u00a0ReentrantLock\u00a0takeLock\u00a0=\u00a0new<\/strong>\u00a0ReentrantLock();\n\/\/\u00a0\u5f53\u961f\u5217\u6ca1\u6709\u6570\u636e\u65f6\uff0c\u5220\u9664\u5143\u7d20\u7ebf\u7a0b\u88ab\u6302\u8d77<\/em>\nprivate<\/strong>\u00a0final<\/strong>\u00a0Condition\u00a0notEmpty\u00a0=\u00a0takeLock.newCondition();\n\/\/\u00a0put,\u00a0offer\u00a0\u7b49\u65b0\u589e\u64cd\u4f5c\u9700\u8981\u6301\u6709\u7684\u9501<\/em>\nprivate<\/strong>\u00a0final<\/strong>\u00a0ReentrantLock\u00a0putLock\u00a0=\u00a0new<\/strong>\u00a0ReentrantLock();\n\/\/\u00a0\u5f53\u961f\u5217\u4e3a\u7a7a\u65f6\uff0c\u6dfb\u52a0\u5143\u7d20\u7ebf\u7a0b\u88ab\u6302\u8d77<\/em>\nprivate<\/strong>\u00a0final<\/strong>\u00a0Condition\u00a0notFull\u00a0=\u00a0putLock.newCondition();<\/code><\/pre>\n\n\n\n
\n\n\n\nArrayBlockingQueue\uff08ABQ\uff09\u5185\u90e8\u5143\u7d20\u4e2a\u6570\u5b57\u6bb5\u4e3a\u4ec0\u4e48\u4f7f\u7528\u7684\u662f\u00a0int \u7c7b\u578b\u7684 count \u53d8\u91cf\uff1f\u4e0d\u62c5\u5fc3\u5e76\u53d1\u4e48<\/strong><\/p>\n\n\n\n\n- \u56e0\u4e3a ABQ \u5185\u90e8\u4f7f\u7528\u7684\u4e00\u628a\u9501\u63a7\u5236\u5165\u961f\u3001\u51fa\u961f\u64cd\u4f5c\uff0c\u540c\u4e00\u65f6\u523b\u53ea\u4f1a\u6709\u5355\u7ebf\u7a0b\u6267\u884c count \u53d8\u91cf\u4fee\u6539<\/strong><\/li>\n\n\n\n
- LBQ \u4f7f\u7528\u7684\u4e24\u628a\u9501\uff0c\u6240\u4ee5\u4f1a\u51fa\u73b0\u4e24\u4e2a\u7ebf\u7a0b\u540c\u65f6\u4fee\u6539 count \u6570\u503c\uff0c\u5982\u679c\u50cf ABQ \u4f7f\u7528 int \u7c7b\u578b\uff0c\u4e24\u4e2a\u6d41\u7a0b\u540c\u65f6\u6267\u884c\u4fee\u6539 count \u4e2a\u6570\uff0c\u4f1a\u9020\u6210\u6570\u636e\u4e0d\u51c6\u786e\uff0c\u6240\u4ee5\u9700\u8981\u4f7f\u7528\u5e76\u53d1\u539f\u5b50\u7c7b\u4fee\u9970<\/strong><\/li>\n<\/ol>\n\n\n\n
\u4e3a\u4ec0\u4e48\u8981\u7528\u539f\u5b50\u7c7b\u7edf\u8ba1\u6570\u91cf\uff1f<\/p>\n\n\n\n
\u539f\u5b50\u7c7b\uff0c\u8001\u751f\u5e38\u8c08\u7684\uff0c\u5b98\u65b9\u8bf4\u53d1\u662f\u89e3\u51b3\u5e76\u53d1\u573a\u666f\u4e0b\u65e0\u9501\u7684\u65b9\u5f0f\u4fdd\u8bc1\u5355\u4e00\u53d8\u91cf\u7684\u6570\u636e\u4e00\u81f4\u6027<\/strong>\uff0c\u591a\u4e2a\u7ebf\u7a0b\u540c\u65f6\u8bfb\u5199\u540c\u4e00\u4e2a\u5171\u4eab\u6570\u636e\u65f6\u5b58\u5728\u591a\u7ebf\u7a0b\u5e76\u53d1\u95ee\u9898\uff1b\u89e3\u51b3\u5e76\u53d1\u5b89\u5168\u95ee\u9898\u7684\u65b9\u5f0f\u6709\u5f88\u591a\u79cd\u65b9\u5f0f,\u00a0\u8457\u540d\u7684\u5c31\u662f JDK \u5e76\u53d1\u5305 concurrent, \u4e3a\u4e86\u5e76\u53d1\u800c\u5b58\u5728\u7684<\/strong><\/p>\n\n\n\n\u8fd9\u4e2a\u5c31\u6bd4\u5982\u5faa\u73af\u53e0\u52a0\u4e00\u4e2a\u6570\u5b57\uff0c\u5728\u591a\u7ebf\u7a0b\u60c5\u51b5\u4e0b\u53ef\u80fd\u4f1a\u51fa\u73b0\u5c11\u52a0\u7684\u60c5\u51b5<\/p>\n\n\n\n
\u53ef\u4ee5\u4f7f\u7528 JDK \u81ea\u5e26\u7684 synchronized, \u901a\u8fc7\u00a0\u4e92\u65a5\u9501\u7684\u65b9\u5f0f\u00a0\u540c\u6b65\u6267\u884c NUM++ \u8fd9\u4e2a\u4ee3\u7801<\/strong><\/p>\n\n\n\n\u4e0d\u4f7f\u7528\u9501\u6765\u89e3\u51b3\u4e0a\u9762\u7684\u975e\u539f\u5b50\u81ea\u589e\u95ee\u9898, \u53ef\u4ee5\u8fd9\u4e48\u6765<\/p>\n\n\n\n![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2025\/12\/1766492023-image-1024x675.png\")
<\/figure>\n\n\n\nAtomicInteger \u662f JDK \u5e76\u53d1\u5305\u4e0b\u63d0\u4f9b\u7684\u00a0\u64cd\u4f5c Integer \u7c7b\u578b\u539f\u5b50\u7c7b<\/strong>, \u901a\u8fc7\u8c03\u7528\u5e95\u5c42\u00a0Unsafe \u7684 CAS \u76f8\u5173\u65b9\u6cd5\u5b9e\u73b0\u539f\u5b50\u64cd\u4f5c<\/strong>\uff1b\u57fa\u4e8e\u4e50\u89c2\u9501\u7684\u601d\u60f3\u5b9e\u73b0\u7684\u4e00\u79cd\u65e0\u9501\u5316\u539f\u5b50\u64cd\u4f5c,\u00a0\u4fdd\u969c\u4e86\u591a\u7ebf\u7a0b\u60c5\u51b5\u4e0b\u5355\u4e00\u53d8\u91cf\u7684\u7ebf\u7a0b\u5b89\u5168\u95ee\u9898<\/strong><\/p>\n\n\n\n\u786c\u4ef6\u7ea7\u522b\u7684\u6307\u4ee4\u907f\u514d\u52a0\u9501\uff0c\u8fd8\u6709\u4e92\u65a5\u9501\u5728synchronized \u5728\u5e76\u53d1\u6bd4\u8f83\u4e25\u91cd\u60c5\u51b5\u4e0b, \u4f1a\u5c06\u9501\u00a0\u5347\u7ea7\u5230\u91cd\u91cf\u7ea7\u9501<\/strong>\uff0c\u907f\u514d\u7528\u6237\u6001\u5230\u5185\u6838\u6001\u8f6c\u53d8\u6d88\u8017\u592a\u591a\u65f6\u95f4\uff1b<\/strong><\/p>\n\n\n\nAtomicInteger \u6709\u4e24\u4e2a\u6784\u9020\u65b9\u6cd5, \u5206\u522b\u662f\u4e00\u4e2a\u65e0\u53c2\u6784\u9020\u53ca\u6709\u53c2\u6784\u9020<\/p>\n\n\n\n
\n- \u65e0\u53c2\u6784\u9020\u7684 value \u5c31\u662f int \u7684\u9ed8\u8ba4\u503c 0<\/li>\n\n\n\n
publicAtomicInteger<\/strong>()\u00a0{\u00a0}<\/code><\/li>\n\n\n\n- \u6709\u53c2\u6784\u9020\u4f1a\u5c06 value \u8d4b\u503c<\/li>\n\n\n\n
publicAtomicInteger<\/strong>(int<\/strong>\u00a0initialValue)\u00a0{
value\u00a0=\u00a0initialValue;
}<\/code><\/li>\n<\/ul>\n\n\n\nAtomicInteger \u6709\u4e09\u4e2a\u91cd\u8981\u7684\u53d8\u91cf, \u5206\u522b\u662f:<\/p>\n\n\n\n
\n- Unsafe:<\/strong>\u00a0\u53ef\u4ee5\u7406\u89e3\u5b83\u5bf9\u4e8e Java \u800c\u8a00, \u662f\u4e00\u4e2a \"BUG\" \u7684\u5b58\u5728,\u00a0\u5728\u00a0AtomicInteger\u00a0\u91cc\u7684\u6700\u5927\u4f5c\u7528\u5c31\u662f\u76f4\u63a5\u64cd\u4f5c\u5185\u5b58\u8fdb\u884c\u503c\u66ff\u6362<\/li>\n\n\n\n
- value:<\/strong> \u4f7f\u7528 int \u7c7b\u578b\u5b58\u50a8 AtomicInteger \u8ba1\u7b97\u7684\u503c, \u901a\u8fc7 volatile \u8fdb\u884c\u4fee\u9970, \u63d0\u4f9b\u4e86\u5185\u5b58\u53ef\u89c1\u6027\u53ca\u9632\u6b62\u6307\u4ee4\u91cd\u6392\u5e8f<\/strong><\/li>\n\n\n\n
- valueOffset:<\/strong> value \u7684\u5185\u5b58\u504f\u79fb\u91cf<\/li>\n<\/ul>\n\n\n\n
\u5e38\u7528API, \u6838\u5fc3\u5b9e\u73b0\u601d\u8def\u90fd\u662f\u4e00\u81f4\u7684, \u4f1a\u7740\u91cd\u8bb2getAndIncrement()<\/strong> \/\/\u00a0\u83b7\u53d6\u5f53\u524d\u503c,\u00a0\u5e76\u8fdb\u884c\u81ea\u589e1<\/p>\n\n\n\npublic final int getAndIncrement() {\n return unsafe.getAndAddInt(this, valueOffset, 1);\n}\n\n\/**\n * unsafe.getAndAddInt\n *\n * @param var1 AtomicInteger \u5bf9\u8c61\n * @param var2 value \u5185\u5b58\u504f\u79fb\u91cf\n * @param var4 \u589e\u52a0\u7684\u503c, \u6bd4\u5982\u5728\u539f\u6709\u503c\u4e0a + 1\n * @return\n *\/\npublic final int getAndAddInt(Object var1, long var2, int var4) {\n int var5;\n do {\n \/\/ \u5185\u5b58\u4e2d value \u6700\u65b0\u503c\n var5 = this.getIntVolatile(var1, var2);\n } while (!this.compareAndSwapInt(var1, var2, var5, var5 + var4));\n\n return var5;\n}<\/code><\/pre>\n\n\n\n\u7cbe\u9ad3\u7684\u5730\u65b9\u5c31\u5728\u4e8e\u00a0compareAndSwapInt(...)<\/strong><\/p>\n\n\n\n\/**\n * \u6bd4\u8f83 var1 \u7684 var2 \u5185\u5b58\u504f\u79fb\u91cf\u5904\u7684\u503c\u662f\u5426\u548c var4 \u76f8\u7b49, \u76f8\u7b49\u5219\u66f4\u65b0\u4e3a var5\n *\n * @param var1 AtomicInteger \u5bf9\u8c61\n * @param var2 value \u5185\u5b58\u504f\u79fb\u91cf\n * @param var4 value \u539f\u672c\u7684\u503c\n * @param var5 \u671f\u671b\u5c06 value \u8bbe\u7f6e\u7684\u503c\n * @return\n *\/\npublic final native boolean compareAndSwapInt(Object var1, long var2, int var4, int var5);<\/code><\/pre>\n\n\n\n\u7531\u4e8e\u662f native \u5173\u952e\u5b57\u4fee\u9970, \u6211\u4eec\u65e0\u6cd5\u67e5\u770b\u5176\u6e90\u7801, \u8bf4\u660e\u4e00\u4e0b\u65b9\u6cd5\u601d\u8def<\/p>\n\n\n\n
1\u3001\u901a\u8fc7 var1(AtomicInteger) \u83b7\u53d6\u5230 var2 (\u5185\u5b58\u504f\u79fb\u91cf) \u7684 value \u503c<\/p>\n\n\n\n
2\u3001\u5c06 value(\u5185\u5b58\u4e2d\u503c) \u4e0e var4(\u7ebf\u7a0b\u5185\u83b7\u53d6\u7684value\u503c) \u8fdb\u884c\u6bd4\u8f83<\/p>\n\n\n\n
3\u3001\u5982\u679c\u76f8\u7b49\u5c06 var5(\u671f\u671b\u503c) \u8bbe\u7f6e\u4e3a\u5185\u5b58\u4e2d\u65b0\u7684 value \u5e76\u8fd4\u56de True<\/p>\n\n\n\n
4\u3001\u4e0d\u60f3\u7b49\u8fd4\u56de False \u7ee7\u7eed\u5c1d\u8bd5\u6267\u884c\u5faa\u73af<\/p>\n\n\n\n
\u8981\u7406\u89e3\u8fd9\u6bb5\u4ee3\u7801\uff0c\u9996\u5148\u8981\u660e\u767d\u5b83\u80cc\u540e\u7684\u6307\u5bfc\u601d\u60f3\u3002<\/p>\n\n\n\n
\nsynchronized<\/code> (\u60b2\u89c2\u9501):<\/strong> \u5047\u8bbe\u4e00\u5b9a\u4f1a\u53d1\u751f\u51b2\u7a81\u3002\u6211\u53bb\u62ff\u6570\u636e\u7684\u65f6\u5019\uff0c\u5148\u628a\u95e8\u9501\u4e0a\uff0c\u4f60\u4eec\u8c01\u90fd\u522b\u8fdb\uff0c\u7b49\u6211\u6539\u5b8c\u4e86\uff0c\u6211\u518d\u5f00\u95e8\u3002\n\n- \u4ee3\u4ef7\uff1a<\/em> \u7ebf\u7a0b\u6302\u8d77\u3001\u4e0a\u4e0b\u6587\u5207\u6362\uff0c\u6027\u80fd\u5f00\u9500\u5927\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- CAS (\u4e50\u89c2\u9501):<\/strong> \u5047\u8bbe\u4e0d\u4f1a\u53d1\u751f\u51b2\u7a81\u3002\u6211\u76f4\u63a5\u53bb\u62ff\u6570\u636e\uff0c\u6539\u7684\u65f6\u5019\u6211\u518d\u770b\u4e00\u773c\uff1a\u201c\u73b0\u5728\u7684\u5185\u5b58\u503c\u662f\u4e0d\u662f\u8fd8\u662f\u6211\u521a\u624d\u62ff\u5230\u7684\u90a3\u4e2a\u503c\uff1f\u201d<\/strong>\n
\n- \u5982\u679c\u662f\uff1a\u8bf4\u660e\u6ca1\u4eba\u6363\u4e71\uff0c\u6211\u76f4\u63a5\u4fee\u6539\u3002<\/li>\n\n\n\n
- \u5982\u679c\u4e0d\u662f\uff1a\u8bf4\u660e\u6709\u4eba\u63d2\u961f\u6539\u8fc7\u4e86\uff0c\u90a3\u6211\u8fd9\u6b21\u4fee\u6539\u5931\u8d25\uff0c\u6211\u91cd\u65b0\u83b7\u53d6\u6700\u65b0\u503c\uff0c\u518d\u8bd5\u4e00\u6b21<\/strong>\uff08\u8fd9\u5c31\u662f\u81ea\u65cb\uff09\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n
getAndAddInt<\/code> \u5c31\u662f\u5178\u578b\u7684\u4e50\u89c2\u9501<\/strong>\u5b9e\u73b0\u3002<\/p>\n\n\n\n![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2025\/12\/1766506020-PixPin_2025-12-24_00-06-27-410x1024.png\")
<\/figure>\n\n\n\n
\n\n\n\n\u4e8c\u3001 \u6e90\u7801\u6df1\u5ea6\u62c6\u89e3<\/h3>\n\n\n\n
\u6211\u4eec\u5c06\u4f60\u63d0\u4f9b\u7684\u4ee3\u7801\u62c6\u89e3\u4e3a\u4e09\u4e2a\u5173\u952e\u52a8\u4f5c\uff1a<\/p>\n\n\n\n
1. \u83b7\u53d6\u5185\u5b58\u5730\u5740 (Setup)<\/h4>\n\n\n\n\/\/ \u5728 AtomicInteger \u521d\u59cb\u5316\u65f6\u5c31\u5df2\u7ecf\u8ba1\u7b97\u597d\u4e86\nlong valueOffset = unsafe.objectFieldOffset\n (AtomicInteger.class.getDeclaredField(\"value\"));<\/code><\/pre>\n\n\n\n\n- \u901a\u900f\u7406\u89e3\uff1a<\/strong> CAS \u64cd\u4f5c\u7684\u662f\u5185\u5b58\u3002Java \u65e0\u6cd5\u76f4\u63a5\u64cd\u4f5c\u5185\u5b58\uff0c\u4f46
Unsafe<\/code> \u7c7b\u53ef\u4ee5\u901a\u8fc7\u201c\u504f\u79fb\u91cf\u201d\u76f4\u63a5\u627e\u5230\u5bf9\u8c61\u5728\u5806\u5185\u5b58\u4e2d\u7684\u5177\u4f53\u4f4d\u7f6e\u3002valueOffset<\/code> \u5c31\u662f value<\/code> \u8fd9\u4e2a\u5b57\u6bb5\u5728 AtomicInteger<\/code> \u5bf9\u8c61\u5185\u5b58\u4e2d\u7684\u201c\u95e8\u724c\u53f7\u201d\u3002<\/li>\n<\/ul>\n\n\n\n2. \u81ea\u65cb\u5faa\u73af (The Spin)<\/h4>\n\n\n\npublic final int getAndAddInt(Object var1, long var2, int var4) {\n int var5;\n do {\n \/\/ \u52a8\u4f5c A: \u83b7\u53d6\u5feb\u7167\n var5 = this.getIntVolatile(var1, var2); \n } while (!this.compareAndSwapInt(var1, var2, var5, var5 + var4)); \/\/ \u52a8\u4f5c B: \u6bd4\u8f83\u5e76\u4ea4\u6362\n return var5;\n}<\/code><\/pre>\n\n\n\n\n- \u52a8\u4f5c A (
getIntVolatile<\/code>)\uff1a<\/strong> \u53bb\u5185\u5b58\u90a3\u4e2a\u201c\u95e8\u724c\u53f7\u201d\u91cc\u770b\u4e00\u773c\uff0c\u73b0\u5728\u7684 value<\/code> \u662f\u591a\u5c11\uff1f\u8bb0\u4e0b\u6765\uff0c\u8bb0\u4f5c var5<\/code>\uff08\u9884\u671f\u503c\uff09\u3002\n\n- \u6ce8\u610f\uff1a<\/em> \u8fd9\u91cc\u7528\u4e86
Volatile<\/code>\uff0c\u4fdd\u8bc1\u4e86\u53ef\u89c1\u6027\uff0c\u770b\u5230\u7684\u4e00\u5b9a\u662f\u4e3b\u5185\u5b58\u4e2d\u6700\u65b0\u7684\u503c\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n- \u52a8\u4f5c B (
compareAndSwapInt<\/code>)\uff1a<\/strong> \u8fd9\u662f\u539f\u5b50\u64cd\u4f5c\u3002\n\n- \u5b83\u62ff\u7740
var5<\/code>\uff08\u6211\u521a\u770b\u5230\u7684\u65e7\u503c\uff09\u548c\u5185\u5b58\u91cc\u73b0\u5728\u771f\u6b63\u7684\u503c\u6bd4\u5bf9\u3002<\/li>\n\n\n\n- CAS \u7684\u6838\u5fc3\u53f0\u8bcd\uff1a<\/strong> \u201c\u5185\u5b58\u5144\uff0c\u6211\u521a\u624d\u770b\u4f60\u662f 0 (var5)\uff0c\u5982\u679c\u4f60\u73b0\u5728\u8fd8\u662f 0\uff0c\u8bf7\u5e2e\u6211\u6539\u6210 1 (var5+var4)\uff1b\u5982\u679c\u4f60\u5df2\u7ecf\u4e0d\u662f 0 \u4e86\uff08\u88ab\u522b\u4eba\u6539\u4e86\uff09\uff0c\u90a3\u5c31\u522b\u52a8\uff0c\u544a\u8bc9\u6211\u5931\u8d25\u3002\u201d<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n
3. \u5faa\u73af\u7684\u610f\u4e49<\/h4>\n\n\n\n\nwhile(!...)<\/code>\uff1a\u5982\u679c CAS \u8fd4\u56de false<\/code>\uff08\u5931\u8d25\u4e86\uff09\uff0c\u53d6\u53cd\u53d8\u6210 true<\/code>\uff0c\u5faa\u73af\u7ee7\u7eed\u3002<\/li>\n\n\n\n- \u518d\u6b21\u5faa\u73af\u65f6\uff1a<\/strong> \u91cd\u65b0\u6267\u884c
getIntVolatile<\/code>\uff0c\u62ff\u5230\u6700\u65b0\u7684\u503c\uff08\u6bd4\u5982\u88ab\u522b\u4eba\u6539\u6210 1 \u4e86\uff09\uff0c\u8fd9\u6b21\u6211\u5c31\u57fa\u4e8e 1 \u518d\u5c1d\u8bd5\u6539\u6210 2\u3002<\/li>\n\n\n\n- \u76f4\u5230\u6210\u529f\uff1a<\/strong> \u76f4\u5230\u6ca1\u6709\u4eba\u8ddf\u6211\u62a2\uff0c\u6211\u6210\u529f\u4fee\u6539\uff0c\u9000\u51fa\u5faa\u73af\u3002<\/li>\n<\/ul>\n\n\n\n
\n\n\n\n\u4e09\u3001 \u56fe\u6587\u573a\u666f\u7684\u201c\u4e0a\u5e1d\u89c6\u89d2\u201d<\/h3>\n\n\n\n
\u8ba9\u6211\u4eec\u7528\u66f4\u751f\u6d3b\u5316\u7684\u4f8b\u5b50\u6765\u91cd\u73b0\u4f60\u63d0\u5230\u7684\u56fe\u6587\u5206\u6790\uff1a<\/p>\n\n\n\n
\u573a\u666f\uff1a<\/strong> \u6b64\u65f6\u5185\u5b58\u91cc value = 0<\/code>\u3002<\/p>\n\n\n\n\n- \u7ebf\u7a0b A \u8fdb\u573a\uff1a<\/strong>\n
\n- \u6267\u884c
getIntVolatile<\/code>\uff0c\u62ff\u5230 var5 = 0<\/code>\u3002<\/li>\n\n\n\n- \u6b64\u65f6\uff0c\u7ebf\u7a0b A \u88ab CPU \u6302\u8d77\u4e86\uff08\u8fd9\u79cd\u60c5\u51b5\u5f88\u5e38\u89c1\uff09\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- \u7ebf\u7a0b B \u8fdb\u573a\uff1a<\/strong>\n
\n- \u6267\u884c
getIntVolatile<\/code>\uff0c\u62ff\u5230 var5 = 0<\/code>\u3002<\/li>\n\n\n\n- \u6267\u884c
compareAndSwap(0, 1)<\/code>\u3002<\/li>\n\n\n\n- \u68c0\u67e5\uff1a<\/strong> \u5185\u5b58\u786e\u5b9e\u662f 0\uff0c\u5339\u914d\u6210\u529f\uff01<\/li>\n\n\n\n
- \u4fee\u6539\uff1a<\/strong> \u5185\u5b58\u53d8\u4e3a 1\u3002<\/li>\n\n\n\n
- \u8fd4\u56de\uff1a<\/strong> True\uff0c\u7ebf\u7a0b B \u6b22\u5929\u559c\u5730\u5730\u8d70\u4e86\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- \u7ebf\u7a0b A \u9192\u4e86\uff1a<\/strong>\n
\n- \u7ee7\u7eed\u6267\u884c
compareAndSwap(0, 1)<\/code>\u3002<\/li>\n\n\n\n- \u68c0\u67e5\uff1a<\/strong> \u50bb\u773c\u4e86\uff0c\u5185\u5b58\u91cc\u73b0\u5728\u662f 1\uff0c\u4e0d\u662f\u6211\u9884\u671f\u7684 0\u3002<\/li>\n\n\n\n
- \u7ed3\u679c\uff1a<\/strong> \u6bd4\u8f83\u5931\u8d25\uff0c\u4e0d\u51c6\u4fee\u6539\uff0c\u8fd4\u56de False\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n
- \u7ebf\u7a0b A \u7684\u201c\u91cd\u8bd5\u201d\uff08\u81ea\u65cb\uff09\uff1a<\/strong>\n
\nwhile<\/code> \u5faa\u73af\u751f\u6548\u3002<\/li>\n\n\n\n- \u91cd\u65b0
getIntVolatile<\/code>\uff0c\u8fd9\u6b21\u62ff\u5230 var5 = 1<\/code>\u3002<\/li>\n\n\n\n- \u6267\u884c
compareAndSwap(1, 2)<\/code>\u3002<\/li>\n\n\n\n- \u68c0\u67e5\uff1a<\/strong> \u5185\u5b58\u662f 1\uff0c\u5339\u914d\u6210\u529f\u3002<\/li>\n\n\n\n
- \u4fee\u6539\uff1a<\/strong> \u5185\u5b58\u53d8\u4e3a 2\u3002<\/li>\n\n\n\n
- \u7ed3\u675f\u3002<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n
\n\n\n\n\u56db\u3001 \u5e95\u5c42\u5230\u5e95\u53d1\u751f\u4e86\u4ec0\u4e48\uff1f(Native)<\/h3>\n\n\n\n
\u4f60\u63d0\u5230\u4e86 native<\/code> \u65b9\u6cd5\u65e0\u6cd5\u770b\u6e90\u7801\uff0c\u4f46\u6211\u4eec\u8981\u901a\u900f\uff0c\u5c31\u5f97\u77e5\u9053\u64cd\u4f5c\u7cfb\u7edf\u5c42\u9762\u5e72\u4e86\u5565\u3002<\/p>\n\n\n\n\u5728 HotSpot \u865a\u62df\u673a\u4e2d\uff0ccompareAndSwapInt<\/code> \u6700\u7ec8\u4f1a\u5bf9\u5e94\u5230 CPU \u7684\u6c47\u7f16\u6307\u4ee4\u3002
\u5728 x86 \u67b6\u6784\u4e0b\uff0c\u8fd9\u6761\u6307\u4ee4\u901a\u5e38\u662f\uff1a<\/p>\n\n\n\nlock cmpxchg ...<\/code><\/pre>\n\n\n\n\ncmpxchg<\/code> (Compare and Exchange):<\/strong> \u8fd9\u662f\u4e00\u4e2a CPU \u6307\u4ee4\uff0c\u786c\u4ef6\u5c42\u9762\u4fdd\u8bc1\u4e86\u201c\u6bd4\u8f83\u201d\u548c\u201c\u4ea4\u6362\u201d\u8fd9\u4e24\u4e2a\u52a8\u4f5c\u662f\u4e0d\u53ef\u62c6\u5206<\/strong>\u7684\u3002\u8981\u4e48\u5168\u505a\uff0c\u8981\u4e48\u5168\u4e0d\u505a\u3002<\/li>\n\n\n\nlock<\/code> \u524d\u7f00\uff1a<\/strong> \u5728\u591a\u6838 CPU \u4e0b\uff0c\u4e3a\u4e86\u9632\u6b62\u591a\u4e2a CPU \u540c\u65f6\u6267\u884c cmpxchg<\/code> \u5bfc\u81f4\u4e71\u5e8f\uff0c\u4f1a\u52a0\u4e0a lock<\/code> \u524d\u7f00\u3002\u5b83\u4f1a\u9501\u5b9a\u603b\u7ebf\uff08\u6216\u5229\u7528\u7f13\u5b58\u4e00\u81f4\u6027\u534f\u8bae MESI\uff09\uff0c\u786e\u4fdd\u540c\u4e00\u65f6\u523b\u53ea\u6709\u4e00\u4e2a CPU \u80fd\u4fee\u6539\u8fd9\u5757\u5185\u5b58\u3002<\/li>\n<\/ol>\n\n\n\n\u7ed3\u8bba\uff1aCAS \u7684\u539f\u5b50\u6027\u662f\u7531 CPU \u786c\u4ef6\u6307\u4ee4\u4fdd\u8bc1\u7684\u3002<\/strong><\/p>\n\n\n\n
\n\n\n\n\u4e94\u3001 \u7f3a\u9677\u7684\u6df1\u5c42\u6b21\u89e3\u8bfb<\/h3>\n\n\n\n
\u4f60\u63d0\u5230\u7684\u4e0d\u8db3\u4e4b\u5904\u975e\u5e38\u7cbe\u51c6\uff0c\u8fd9\u91cc\u505a\u8fdb\u4e00\u6b65\u7684\u6269\u5c55\uff1a<\/p>\n\n\n\n
1. CPU \u5f00\u9500 (The Spin Lock Problem)<\/h4>\n\n\n\n\n- \u73b0\u8c61\uff1a<\/strong> \u5982\u679c\u6709 1000 \u4e2a\u7ebf\u7a0b\u540c\u65f6\u7ade\u4e89\u4e00\u4e2a\u53d8\u91cf\uff0c\u540c\u4e00\u65f6\u523b\u53ea\u6709\u4e00\u4e2a\u80fd\u6210\u529f\uff0c\u5269\u4e0b 999 \u4e2a\u90fd\u5728
do-while<\/code> \u91cc\u72c2\u8f6c\u3002<\/li>\n\n\n\n- \u540e\u679c\uff1a<\/strong> CPU \u4f7f\u7528\u7387\u98d9\u5347\uff0c\u4f46\u6ca1\u5e72\u6b63\u4e8b\uff08\u90fd\u5728\u91cd\u8bd5\uff09\u3002<\/li>\n\n\n\n
- \u89e3\u51b3\uff1a<\/strong>LongAdder<\/strong>\u3002\n
\n- \u539f\u7406\uff1a<\/em> \u5206\u6563\u70ed\u70b9\u3002\u65e2\u7136\u5927\u5bb6\u62a2\u4e00\u4e2a
value<\/code> \u6b64\u65f6\u592a\u6324\uff0c\u90a3\u6211\u5c31\u641e\u4e00\u4e2a\u6570\u7ec4 Cell[]<\/code>\u3002\u7ebf\u7a0b A \u62a2 Cell[0]<\/code>\uff0c\u7ebf\u7a0b B \u62a2 Cell[1]<\/code>\u2026 \u6700\u540e\u53d6\u503c\u7684\u65f6\u5019\u628a\u6570\u7ec4\u91cc\u7684\u503c\u52a0\u8d77\u6765\u3002\u8fd9\u5c31\u662f\u7a7a\u95f4\u6362\u65f6\u95f4<\/strong>\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n2. ABA \u95ee\u9898 (The \"Ex-Girlfriend\" Problem)<\/h4>\n\n\n\n\n- \u901a\u4fd7\u89e3\u91ca\uff1a<\/strong>\n
\n