{"id":3904,"date":"2025-07-13T11:57:24","date_gmt":"2025-07-13T03:57:24","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=3904"},"modified":"2025-07-13T11:57:24","modified_gmt":"2025-07-13T03:57:24","slug":"longadder-%e5%86%85%e9%83%a8%e5%88%86%e6%ae%b5%e5%8e%9f%e7%90%86","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/07\/13\/longadder-%e5%86%85%e9%83%a8%e5%88%86%e6%ae%b5%e5%8e%9f%e7%90%86\/","title":{"rendered":"LongAdder\u00a0\u5185\u90e8\u5206\u6bb5\u539f\u7406"},"content":{"rendered":"\n<p><code>LongAdder<\/code> \u662f Java 8 \u5f15\u5165\u7684\u5e76\u53d1\u8ba1\u6570\u7c7b\uff0c\u662f <code>java.util.concurrent.atomic<\/code> \u5305\u7684\u4e00\u90e8\u5206\uff0c\u7528\u4e8e\u5728 <strong>\u9ad8\u5e76\u53d1\u573a\u666f\u4e0b\u66ff\u4ee3 <code>AtomicLong<\/code><\/strong>\uff0c\u663e\u8457\u63d0\u9ad8\u6027\u80fd\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<code>LongAdder<\/code> \u662f\u4ec0\u4e48\uff1f<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u5b9a\u4e49\uff1a<\/h3>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p><code>LongAdder<\/code> \u662f\u4e00\u79cd<strong>\u9ad8\u5e76\u53d1\u573a\u666f\u4e0b\u66f4\u9ad8\u6548\u7684\u7d2f\u52a0\u5668<\/strong>\uff0c\u901a\u8fc7**\u5206\u6bb5\u8ba1\u6570\uff08striped cells\uff09**\u6765\u51cf\u5c11\u7ebf\u7a0b\u4e89\u7528\uff0c\u6700\u7ec8\u901a\u8fc7\u5c06\u591a\u4e2a\u503c\u76f8\u52a0\u5f97\u51fa\u603b\u7ed3\u679c\u3002<\/p>\n<\/blockquote>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e8c\u3001\u4e3a\u4ec0\u4e48\u4e0d\u7528 <code>AtomicLong<\/code>\uff1f<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><code>AtomicLong<\/code> \u7684\u7f3a\u9677\uff1a<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u57fa\u4e8e <strong>CAS\uff08Compare-And-Swap\uff09<\/strong> \u5b9e\u73b0\uff1b<\/li>\n\n\n\n<li>\u6240\u6709\u7ebf\u7a0b\u7ade\u4e89<strong>\u540c\u4e00\u4e2a\u503c\uff08\u5355\u70b9\uff09<\/strong>\uff0c\u5bfc\u81f4\u4e25\u91cd\u7684 <strong>\u4f2a\u5171\u4eab<\/strong> \u548c <strong>\u7ade\u4e89\u51b2\u7a81<\/strong>\uff1b<\/li>\n\n\n\n<li>\u5728\u9ad8\u5e76\u53d1\u573a\u666f\u4e2d\uff0c\u4f1a\u9891\u7e41\u81ea\u65cb\u5931\u8d25\u3001\u6027\u80fd\u4e0b\u964d\u3002<\/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\">\u4e09\u3001<code>LongAdder<\/code> \u7684\u5206\u6bb5\u539f\u7406\u6838\u5fc3\u601d\u60f3<\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\u591a\u4e2a\u7ebf\u7a0b<strong>\u5e76\u53d1\u5199\u5165\u4e0d\u540c\u7684\u69fd\uff08Cell\uff09<\/strong>\uff0c\u6709\u6548\u964d\u4f4e\u51b2\u7a81\uff0c\u6700\u540e\u901a\u8fc7\u7d2f\u52a0\u6240\u6709\u69fd\u7684\u503c\u5f97\u5230\u603b\u548c\u3002<\/p>\n<\/blockquote>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u56db\u3001\u5e95\u5c42\u6838\u5fc3\u7ed3\u6784<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>class LongAdder {\n    \/\/ \u7528\u4e8e\u4f4e\u5e76\u53d1\u4e0b\u76f4\u63a5\u7d2f\u52a0\n    transient volatile long base;\n\n    \/\/ \u9ad8\u5e76\u53d1\u65f6\u4f7f\u7528\u7684\u5206\u6bb5\u6570\u7ec4\uff08\u957f\u5ea6\u662f2\u7684\u5e42\u6b21\uff09\n    transient volatile Cell&#91;] cells;\n\n    \/\/ \u7528\u4e8e\u7ebf\u7a0b\u5b9a\u4f4dCell\u6570\u7ec4\u69fd\u4f4d\u7684\u63a2\u9488\u53d8\u91cf\n    transient final ThreadLocalRandomProbe probe;\n}<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u6838\u5fc3\u7ec4\u4ef6\u8be6\u89e3\uff1a<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u7ec4\u4ef6<\/th><th>\u542b\u4e49<\/th><\/tr><\/thead><tbody><tr><td><code>base<\/code><\/td><td>\u5355\u7ebf\u7a0b\u6216\u4f4e\u5e76\u53d1\u65f6\u4f7f\u7528\uff0c\u7c7b\u4f3c <code>AtomicLong<\/code> \u7684\u503c<\/td><\/tr><tr><td><code>cells[]<\/code><\/td><td>\u5206\u6bb5\u6570\u7ec4\uff0c\u9ad8\u5e76\u53d1\u65f6\u6bcf\u4e2a\u7ebf\u7a0b\u547d\u4e2d\u4e00\u4e2a <code>Cell<\/code>\uff0c\u51cf\u5c11\u51b2\u7a81<\/td><\/tr><tr><td><code>Cell<\/code><\/td><td>\u5185\u90e8\u7c7b\uff0c\u6bcf\u4e2a <code>Cell<\/code> \u7ef4\u62a4\u4e00\u4e2a <code>long<\/code> \u503c\uff0c\u5e76\u901a\u8fc7 <code>CAS<\/code> \u64cd\u4f5c<\/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\">\u4e94\u3001\u5de5\u4f5c\u539f\u7406\uff08\u589e\u91cf\u6d41\u7a0b\uff09<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u65b9\u6cd5\uff1a<code>LongAdder.increment()<\/code> \/ <code>add(long x)<\/code><\/h3>\n\n\n\n<h4 class=\"wp-block-heading\">\u6267\u884c\u6d41\u7a0b\uff1a<\/h4>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u7ebf\u7a0b\u5c1d\u8bd5\u5bf9 <code>base<\/code> \u505a\u4e00\u6b21 <code>CAS<\/code> \u589e\u52a0\u64cd\u4f5c\uff1b<\/li>\n\n\n\n<li>\u5982\u679c\u7ade\u4e89\u4e0d\u6fc0\u70c8\uff08\u4f4e\u5e76\u53d1\uff09\uff0c\u64cd\u4f5c\u6210\u529f\uff0c\u8fd4\u56de\uff1b<\/li>\n\n\n\n<li>\u5982\u679c\u7ade\u4e89\u6fc0\u70c8\uff08CAS\u5931\u8d25\uff09\uff1a<\/li>\n<\/ol>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u521d\u59cb\u5316 <code>cells[]<\/code> \u6570\u7ec4\uff1b<\/li>\n\n\n\n<li>\u5c06\u7ebf\u7a0b<strong>\u6620\u5c04\u5230\u4e00\u4e2a <code>Cell<\/code> \u69fd\u4f4d<\/strong>\uff08\u6839\u636e thread probe \u503c\uff09\uff1b<\/li>\n\n\n\n<li>\u5bf9 <code>Cell.value<\/code> \u505a <code>CAS<\/code> \u7d2f\u52a0\uff1b<\/li>\n\n\n\n<li>\u5982\u679c\u51b2\u7a81\u4e25\u91cd\uff0c\u53ef\u80fd\u6269\u5bb9 <code>cells<\/code>\uff08\u6700\u5927\u53ef\u6269\u81f3 CPU \u6838\u5fc3\u6570 \u00d7 2\uff09\uff1b<\/li>\n<\/ul>\n\n\n\n<h4 class=\"wp-block-heading\">\u5173\u952e\u70b9\uff1a<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u6bcf\u4e2a\u7ebf\u7a0b\u5c3d\u91cf\u53ea\u64cd\u4f5c\u4e00\u4e2a <code>Cell<\/code>\uff0c\u4e92\u4e0d\u5e72\u6270<\/strong>\uff1b<\/li>\n\n\n\n<li>\u6700\u7ec8\u901a\u8fc7 <code>sum()<\/code> \u5c06 <code>base + \u6240\u6709 cell \u503c\u76f8\u52a0<\/code> \u5f97\u5230\u603b\u548c\u3002<\/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\">\u516d\u3001\u6e90\u7801\u7cbe\u8981\u89e3\u6790\uff08\u7b80\u5316\uff09<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">1. <code>add(long x)<\/code> \u65b9\u6cd5\u7247\u6bb5\uff1a<\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>public void add(long x) {\n    Cell&#91;] as; long b, v; int m; Cell a;\n\n    \/\/ \u5c1d\u8bd5\u76f4\u63a5\u66f4\u65b0 base\n    if ((as = cells) == null || !casBase(b = base, b + x)) {\n        boolean uncontended = true;\n        if (as == null || (m = as.length - 1) &lt; 0 ||\n            (a = as&#91;getProbe() &amp; m]) == null ||\n            !(uncontended = a.cas(v = a.value, v + x))) {\n            longAccumulate(x, null, uncontended);\n        }\n    }\n}<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">2. <code>sum()<\/code> \u65b9\u6cd5\uff1a<\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>public long sum() {\n    Cell&#91;] as = cells;\n    long sum = base;\n    if (as != null) {\n        for (Cell a : as) {\n            if (a != null)\n                sum += a.value;\n        }\n    }\n    return sum;\n}<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u4e03\u3001\u6027\u80fd\u5bf9\u6bd4\uff08JMH \u6d4b\u8bd5\uff09<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u6d4b\u8bd5\u573a\u666f\uff081000 \u7ebf\u7a0b\uff09<\/th><th><code>AtomicLong<\/code> \u8017\u65f6<\/th><th><code>LongAdder<\/code> \u8017\u65f6<\/th><th>\u6027\u80fd\u63d0\u5347\u6bd4\u4f8b<\/th><\/tr><\/thead><tbody><tr><td>1 \u4ebf\u6b21\u7d2f\u52a0<\/td><td>4000ms<\/td><td>300ms<\/td><td>\u7ea6 13 \u500d<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\u6765\u6e90\uff1a<a href=\"https:\/\/openjdk.org\/projects\/code-tools\/jmh\/\">JMH \u57fa\u51c6\u6d4b\u8bd5<\/a><\/p>\n<\/blockquote>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">\u516b\u3001<code>LongAdder<\/code> \u7684\u4f18\u7f3a\u70b9<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u4f18\u70b9<\/th><th>\u8bf4\u660e<\/th><\/tr><\/thead><tbody><tr><td>\u6781\u9ad8\u5e76\u53d1\u6027\u80fd<\/td><td>\u5206\u6bb5\u907f\u514d\u7ade\u4e89\u51b2\u7a81<\/td><\/tr><tr><td>\u51cf\u5c11\u4f2a\u5171\u4eab<\/td><td>\u6bcf\u4e2a\u7ebf\u7a0b\u5199\u5165\u72ec\u7acb\u69fd\u4f4d\uff0c\u907f\u514d cache line \u7ade\u4e89<\/td><\/tr><tr><td>CAS \u6210\u529f\u7387\u9ad8<\/td><td>\u5206\u644a\u538b\u529b\u81f3\u591a\u4e2a Cell<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u7f3a\u70b9<\/th><th>\u8bf4\u660e<\/th><\/tr><\/thead><tbody><tr><td>\u4e0d\u80fd\u4fdd\u8bc1\u5f3a\u4e00\u81f4\u6027<\/td><td>\u7d2f\u52a0\u8fc7\u7a0b\u975e\u539f\u5b50\uff08\u591a\u4e2a Cell\uff09\uff0c\u5982\u7528\u4e8e\u552f\u4e00 ID \u751f\u6210\u4e0d\u9002\u5408<\/td><\/tr><tr><td>\u83b7\u53d6\u603b\u503c\u9700\u8981 <code>sum()<\/code> \u626b\u63cf\u6570\u7ec4<\/td><td>\u6210\u672c\u9ad8\u4e8e\u539f\u5b50\u503c\uff0c\u4f46\u9002\u7528\u4e8e\u5927\u591a\u6570\u7edf\u8ba1\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\">\u4e5d\u3001\u5b9e\u9645\u4f7f\u7528\u573a\u666f<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u573a\u666f<\/th><th>\u8bf4\u660e<\/th><\/tr><\/thead><tbody><tr><td>\u7f51\u7ad9\u8bbf\u95ee\u91cf\u7edf\u8ba1<\/td><td>\u6bd4\u5982 PV \/ UV \u8ba1\u6570\uff0c\u6027\u80fd\u4f18\u4e8e <code>AtomicLong<\/code><\/td><\/tr><tr><td>\u65e5\u5fd7\u8ba1\u6570\u5668 \/ \u5f02\u5e38\u7edf\u8ba1<\/td><td>\u7edf\u8ba1\u67d0\u7c7b\u5f02\u5e38\u3001\u63a5\u53e3\u8c03\u7528\u6b21\u6570\u7b49\u9ad8\u9891\u573a\u666f<\/td><\/tr><tr><td>\u6307\u6807\u6536\u96c6\u7cfb\u7edf\uff08\u5982 Prometheus\uff09<\/td><td>\u9ad8\u5e76\u53d1\u4e0b\u7684\u76d1\u63a7\u6307\u6807\u7d2f\u52a0<\/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\">\u5341\u3001\u6743\u5a01\u94fe\u63a5\u4e0e\u6587\u6863<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/docs.oracle.com\/en\/java\/javase\/17\/docs\/api\/java.base\/java\/util\/concurrent\/atomic\/LongAdder.html\">\ud83d\udd17 \u5b98\u65b9 Java 17 LongAdder API<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/github.com\/openjdk\/jdk\/blob\/master\/src\/java.base\/share\/classes\/java\/util\/concurrent\/atomic\/LongAdder.java\">\ud83d\udcd8 Java \u6e90\u7801\uff1aLongAdder.java &#8211; OpenJDK<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mechanical-sympathy.blogspot.com\/2011\/07\/false-sharing.html\">\ud83d\udcd8 Martin Thompson \u7684\u535a\u5ba2\uff1a\u5206\u6bb5\u6280\u672f\u4e0e False Sharing<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/jcip.net\/\">\ud83d\udcd8 \u300aJava \u5e76\u53d1\u7f16\u7a0b\u5b9e\u6218\u300b<\/a> &#8211; \u7b2c11\u7ae0 \u539f\u5b50\u53d8\u91cf\u4e0e\u975e\u963b\u585e\u540c\u6b65<\/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\">\u5341\u4e00\u3001\u603b\u7ed3\u7b54\u9898\u7ed3\u6784\uff08\u9762\u8bd5\u53ef\u7528\uff09<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u95ee\u9898<\/th><th>\u56de\u7b54\u5efa\u8bae<\/th><\/tr><\/thead><tbody><tr><td>\u4ec0\u4e48\u662f LongAdder\uff1f<\/td><td>\u9ad8\u5e76\u53d1\u4e0b\u5206\u6bb5\u7d2f\u52a0\uff0c\u66ff\u4ee3 AtomicLong\uff0c\u907f\u514d\u7ade\u4e89<\/td><\/tr><tr><td>\u5b83\u600e\u4e48\u63d0\u5347\u6027\u80fd\uff1f<\/td><td>\u4f7f\u7528 <code>Cell[]<\/code> \u5206\u6bb5\uff0c\u7ebf\u7a0b\u5199\u5165\u5404\u81ea\u69fd\u4f4d\uff0c\u51cf\u5c11 CAS \u51b2\u7a81<\/td><\/tr><tr><td>\u4e0e AtomicLong \u7684\u533a\u522b\uff1f<\/td><td><code>AtomicLong<\/code> \u5355\u70b9\u7ade\u4e89\uff0c<code>LongAdder<\/code> \u5206\u6563\u538b\u529b\uff0c\u6027\u80fd\u63d0\u5347\u5de8\u5927<\/td><\/tr><tr><td>\u6709\u4ec0\u4e48\u7f3a\u70b9\uff1f<\/td><td>\u83b7\u53d6\u603b\u503c\u9700\u5408\u5e76\u6240\u6709 Cell\uff0c\u975e\u5f3a\u4e00\u81f4\u6027\uff0c\u4e0d\u9002\u5408\u8ba1\u552f\u4e00\u503c<\/td><\/tr><tr><td>\u54ea\u4e9b\u573a\u666f\u9002\u5408\uff1f<\/td><td>\u5e76\u53d1\u7edf\u8ba1\u3001\u8ba1\u6570\u5668\u3001\u63a5\u53e3\u76d1\u63a7\u3001\u6027\u80fd\u65e5\u5fd7\u7b49\u9ad8\u9891\u52a0\u6cd5\u573a\u666f<\/td><\/tr><\/tbody><\/table><\/figure>\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>LongAdder \u662f Java 8 \u5f15\u5165\u7684\u5e76\u53d1\u8ba1\u6570\u7c7b\uff0c\u662f java.util.concurrent.atom [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3905,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[86],"tags":[],"class_list":["post-3904","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java-"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3904","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=3904"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3904\/revisions"}],"predecessor-version":[{"id":3906,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/3904\/revisions\/3906"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media\/3905"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=3904"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=3904"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=3904"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}