{"id":3928,"date":"2025-07-20T10:48:00","date_gmt":"2025-07-20T02:48:00","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=3928"},"modified":"2025-07-20T10:48:00","modified_gmt":"2025-07-20T02:48:00","slug":"aqs-%e4%b8%ad%e7%9a%84%e5%85%ac%e5%b9%b3%e9%94%81-vs-%e9%9d%9e%e5%85%ac%e5%b9%b3%e9%94%81%e5%a6%82%e4%bd%95%e5%ae%9e%e7%8e%b0%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/07\/20\/aqs-%e4%b8%ad%e7%9a%84%e5%85%ac%e5%b9%b3%e9%94%81-vs-%e9%9d%9e%e5%85%ac%e5%b9%b3%e9%94%81%e5%a6%82%e4%bd%95%e5%ae%9e%e7%8e%b0%ef%bc%9f\/","title":{"rendered":"AQS \u4e2d\u7684\u516c\u5e73\u9501 vs \u975e\u516c\u5e73\u9501\u5982\u4f55\u5b9e\u73b0\uff1f"},"content":{"rendered":"\n<p>\u5728 Java \u7684 AQS\uff08AbstractQueuedSynchronizer\uff09\u4e2d\uff0c<strong>\u516c\u5e73\u9501 vs \u975e\u516c\u5e73\u9501<\/strong>\u662f\u63a7\u5236\u7ebf\u7a0b\u83b7\u53d6\u9501\u987a\u5e8f\u7684\u4e24\u79cd\u7b56\u7565\u3002\u5b83\u4eec\u5206\u522b\u4ee3\u8868\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u516c\u5e73\u9501\uff08Fair Lock\uff09<\/strong>\uff1a\u7ebf\u7a0b\u83b7\u53d6\u9501<strong>\u9075\u5faa\u5148\u6765\u5148\u670d\u52a1<\/strong>\uff0c\u6392\u961f\u6267\u884c\u3002<\/li>\n\n\n\n<li><strong>\u975e\u516c\u5e73\u9501\uff08Non-Fair Lock\uff09<\/strong>\uff1a\u7ebf\u7a0b\u6765\u5c31\u5c1d\u8bd5\u62a2\u9501\uff0c<strong>\u53ef\u80fd\u63d2\u961f<\/strong>\uff0c\u4e0d\u4e00\u5b9a\u5148\u5230\u5148\u5f97\u3002<\/li>\n<\/ul>\n\n\n\n<p>\u8fd9\u4e24\u79cd\u7b56\u7565\u5f71\u54cd\u9501\u7684\u83b7\u53d6\u6548\u7387\u3001\u7ebf\u7a0b\u8c03\u5ea6\u7684\u516c\u5e73\u6027\uff0c\u5177\u4f53\u7531 AQS \u4e0e <code>ReentrantLock<\/code> \u7684\u5b9e\u73b0\u65b9\u5f0f\u51b3\u5b9a\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e00\u3001\u5feb\u901f\u7ed3\u8bba\u5bf9\u6bd4\u8868<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u7279\u6027<\/th><th>\u516c\u5e73\u9501 (<code>fair=true<\/code>)<\/th><th>\u975e\u516c\u5e73\u9501 (<code>fair=false<\/code>)<\/th><\/tr><\/thead><tbody><tr><td>\u83b7\u53d6\u987a\u5e8f<\/td><td>\u4e25\u683c\u6309\u7167\u961f\u5217 FIFO \u987a\u5e8f<\/td><td>\u53ef\u80fd\u201c\u63d2\u961f\u201d\uff0c\u53ea\u8981\u9501\u7a7a\u95f2\u5c31\u62a2<\/td><\/tr><tr><td>\u6027\u80fd\u8868\u73b0<\/td><td>\u8f83\u5dee\uff08\u7ebf\u7a0b\u9891\u7e41\u6302\u8d77\/\u5524\u9192\uff09<\/td><td>\u66f4\u9ad8\u6548\uff08\u51cf\u5c11\u4e0a\u4e0b\u6587\u5207\u6362\uff09<\/td><\/tr><tr><td>\u7ebf\u7a0b\u9965\u997f\u53ef\u80fd<\/td><td>\u51e0\u4e4e\u6ca1\u6709<\/td><td>\u6709\u53ef\u80fd\u67d0\u7ebf\u7a0b\u957f\u671f\u62a2\u4e0d\u5230\u9501<\/td><\/tr><tr><td>\u5b9e\u73b0\u590d\u6742\u5ea6<\/td><td>\u8f83\u9ad8\uff08\u9700\u8981\u5224\u65ad\u524d\u9a71\u8282\u70b9\uff09<\/td><td>\u7b80\u5355\uff08\u76f4\u63a5\u5c1d\u8bd5 CAS\uff09<\/td><\/tr><tr><td>AQS \u65b9\u6cd5<\/td><td>\u91cd\u5199 <code>tryAcquire()<\/code> + <code>hasQueuedPredecessors()<\/code> \u5224\u65ad<\/td><td>\u76f4\u63a5 CAS \u5c1d\u8bd5\u66f4\u65b0 <code>state<\/code><\/td><\/tr><tr><td>\u5e94\u7528\u573a\u666f<\/td><td>\u5b9e\u65f6\u6027\u9ad8\u3001\u5bf9\u987a\u5e8f\u8981\u6c42\u5f3a\uff08\u5982\u4efb\u52a1\u8c03\u5ea6\uff09<\/td><td>\u5927\u591a\u6570\u9ad8\u5e76\u53d1\u3001\u541e\u5410\u91cf\u4f18\u5148\u7684\u5e94\u7528\u573a\u666f<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e8c\u3001\u6e90\u7801\u89c6\u89d2\u5256\u6790\uff1a\u5982\u4f55\u5b9e\u73b0\u516c\u5e73\/\u975e\u516c\u5e73<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><code>ReentrantLock<\/code> \u662f\u5982\u4f55\u6307\u5b9a\u516c\u5e73\u6027\u7684\uff1f<\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>ReentrantLock fairLock = new ReentrantLock(true);   \/\/ \u516c\u5e73\u9501\nReentrantLock unfairLock = new ReentrantLock(false); \/\/ \u975e\u516c\u5e73\u9501\uff08\u9ed8\u8ba4\uff09<\/code><\/pre>\n\n\n\n<p>\u5e95\u5c42\u6e90\u7801\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public ReentrantLock(boolean fair) {\n    sync = fair ? new FairSync() : new NonfairSync();\n}<\/code><\/pre>\n\n\n\n<p>\u5b83\u5185\u90e8\u7528\u4e24\u4e2a\u5b50\u7c7b\u6765\u5b9e\u73b0\u4e0d\u540c\u7b56\u7565\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>FairSync extends Sync<\/code><\/li>\n\n\n\n<li><code>NonfairSync extends Sync<\/code><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">1. \u975e\u516c\u5e73\u9501\uff1a<code>NonfairSync.tryAcquire()<\/code><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>final boolean nonfairTryAcquire(int acquires) {\n    final Thread current = Thread.currentThread();\n    int c = getState();\n\n    if (c == 0) {\n        \/\/ \u76f4\u63a5\u5c1d\u8bd5\u83b7\u53d6\u9501\uff0c\u62a2\u5230\u5c31\u6210\u529f\uff08\u4e0d\u7ba1\u961f\u5217\u6709\u6ca1\u6709\u5176\u4ed6\u7ebf\u7a0b\uff09\n        if (compareAndSetState(0, acquires)) {\n            setExclusiveOwnerThread(current);\n            return true;\n        }\n    }\n    \/\/ \u53ef\u91cd\u5165\u903b\u8f91\n    else if (current == getExclusiveOwnerThread()) {\n        int nextc = c + acquires;\n        setState(nextc);\n        return true;\n    }\n    return false;\n}<\/code><\/pre>\n\n\n\n<p><strong>\u5173\u952e\u70b9<\/strong>\uff1a\u6ca1\u6709\u68c0\u67e5\u7b49\u5f85\u961f\u5217\uff01\u9501\u7a7a\u5c31\u62a2\uff0c\u62a2\u5230\u4e3a\u738b\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">2. \u516c\u5e73\u9501\uff1a<code>FairSync.tryAcquire()<\/code><\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>protected final boolean tryAcquire(int acquires) {\n    final Thread current = Thread.currentThread();\n    int c = getState();\n\n    if (c == 0) {\n        \/\/ \ud83d\udc47 \u5173\u952e\uff1a\u516c\u5e73\u9501\u5fc5\u987b\u201c\u6392\u961f\u201d\n        if (!hasQueuedPredecessors() &amp;&amp;\n            compareAndSetState(0, acquires)) {\n            setExclusiveOwnerThread(current);\n            return true;\n        }\n    }\n    \/\/ \u53ef\u91cd\u5165\n    else if (current == getExclusiveOwnerThread()) {\n        int nextc = c + acquires;\n        setState(nextc);\n        return true;\n    }\n    return false;\n}<\/code><\/pre>\n\n\n\n<p>\ud83d\udd0d <code>hasQueuedPredecessors()<\/code>\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>public final boolean hasQueuedPredecessors() {\n    Node h, t, s;\n    return ((h = head) != (t = tail) &amp;&amp;\n            ((s = h.next) == null || s.thread != Thread.currentThread()));\n}<\/code><\/pre>\n\n\n\n<p><strong>\u5173\u952e\u70b9<\/strong>\uff1a\u5f53\u524d\u7ebf\u7a0b\u53ea\u6709\u5728**\u81ea\u5df1\u662f\u7b49\u5f85\u961f\u5217\u7684\u5934\u8282\u70b9\uff08\u6392\u5728\u7b2c\u4e00\uff09**\u624d\u5141\u8bb8\u83b7\u53d6\u9501\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e09\u3001\u4e3e\u4e2a\u7ebf\u7a0b\u62a2\u9501\u7684\u4f8b\u5b50\u5bf9\u6bd4<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u573a\u666f\uff1a<\/h3>\n\n\n\n<p>\u4e09\u4e2a\u7ebf\u7a0b A\u3001B\u3001C\uff0c\u4f9d\u6b21\u8bf7\u6c42\u9501\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u516c\u5e73\u9501\uff1a<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>  A \u83b7\u5f97\u9501 \u2192 A \u91ca\u653e \u2192 B \u83b7\u5f97 \u2192 B \u91ca\u653e \u2192 C \u83b7\u5f97<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u975e\u516c\u5e73\u9501\uff1a<\/li>\n<\/ul>\n\n\n\n<pre class=\"wp-block-code\"><code>  A \u83b7\u5f97\u9501 \u2192 A \u91ca\u653e \u2192 C \u62a2\u5148 \u2192 B \u88ab\u997f\u6b7b\u4e00\u4f1a<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u56db\u3001\u4e3a\u4ec0\u4e48\u975e\u516c\u5e73\u9501\u66f4\u5feb\uff1f<\/h2>\n\n\n\n<p>\u975e\u516c\u5e73\u9501\u51cf\u5c11\u4e86\u4ee5\u4e0b\u5f00\u9500\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4e0d\u68c0\u67e5\u7b49\u5f85\u961f\u5217\uff08\u5c11\u4e86 <code>hasQueuedPredecessors()<\/code>\uff09<\/li>\n\n\n\n<li>\u907f\u514d\u7ebf\u7a0b\u9891\u7e41\u6302\u8d77\/\u5524\u9192\uff08\u76f4\u63a5\u5c1d\u8bd5\uff09<\/li>\n\n\n\n<li>\u51cf\u5c11\u7ebf\u7a0b\u4e0a\u4e0b\u6587\u5207\u6362<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">\u6027\u80fd\u5dee\u5f02\u6d4b\u8bd5\uff08\u9ad8\u5e76\u53d1\u573a\u666f\uff09\uff1a<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u9501\u7c7b\u578b<\/th><th>\u541e\u5410\u91cf\uff08\u8bf7\u6c42\u6570\/\u79d2\uff09<\/th><\/tr><\/thead><tbody><tr><td>\u975e\u516c\u5e73\u9501<\/td><td>\u2705 \u66f4\u9ad8<\/td><\/tr><tr><td>\u516c\u5e73\u9501<\/td><td>\u274c \u660e\u663e\u4e0b\u964d<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>\u4f46\u6ce8\u610f\uff1a\u975e\u516c\u5e73\u9501\u5b58\u5728<strong>\u7ebf\u7a0b\u9965\u997f\u98ce\u9669<\/strong>\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e94\u3001\u5b98\u65b9\u4e0e\u6e90\u7801\u8d44\u6599<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/github.com\/openjdk\/jdk\/blob\/master\/src\/java.base\/share\/classes\/java\/util\/concurrent\/locks\/ReentrantLock.java\">OpenJDK ReentrantLock \u6e90\u7801<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/github.com\/openjdk\/jdk\/blob\/master\/src\/java.base\/share\/classes\/java\/util\/concurrent\/locks\/AbstractQueuedSynchronizer.java\">OpenJDK AQS \u6e90\u7801<\/a><\/li>\n\n\n\n<li>\u300aJava \u5e76\u53d1\u7f16\u7a0b\u5b9e\u6218\u300b\u7b2c 14 \u7ae0<\/li>\n\n\n\n<li>\u300a\u6df1\u5165\u7406\u89e3 Java \u865a\u62df\u673a\u300b\u7b2c 13 \u7ae0\uff08\u9501\u4f18\u5316\u4e0e\u516c\u5e73\u6027\uff09<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u603b\u7ed3\u53e3\u8bc0<\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p><strong>\u516c\u5e73\u6392\u961f\uff0c\u4fdd\u969c\u987a\u5e8f\uff1b\u975e\u516c\u5e73\u9501\uff0c\u62a2\u5360\u4f18\u5148\uff1b\u6027\u80fd\u4f18\u5148\u9009\u975e\u516c\u5e73\uff0c\u8c03\u5ea6\u4e25\u683c\u7528\u516c\u5e73\u9501\u3002<\/strong><\/p>\n<\/blockquote>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p>\u66f4\u591a\u8be6\u7ec6\u5185\u5bb9\u8bf7\u5173\u6ce8\u5176\u4ed6\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728 Java \u7684 AQS\uff08AbstractQueuedSynchronizer\uff09\u4e2d\uff0c\u516c\u5e73\u9501 vs \u975e\u516c\u5e73\u9501\u662f\u63a7 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3929,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[86,68],"tags":[],"class_list":["post-3928","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java-","category-java"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3928","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=3928"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3928\/revisions"}],"predecessor-version":[{"id":3930,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3928\/revisions\/3930"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media\/3929"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=3928"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=3928"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=3928"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}