{"id":200057,"date":"2020-11-15T03:59:20","date_gmt":"2020-11-14T19:59:20","guid":{"rendered":"http:\/\/4563.org\/?p=200057"},"modified":"2020-11-15T03:59:20","modified_gmt":"2020-11-14T19:59:20","slug":"aqs-%e5%85%ac%e5%b9%b3%e9%94%81%e7%9c%9f%e7%9a%84%e5%ae%8c%e5%85%a8%e5%85%ac%e5%b9%b3%e5%90%97%ef%bc%9f","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=200057","title":{"rendered":"AQS \u516c\u5e73\u9501\u771f\u7684\u5b8c\u5168\u516c\u5e73\u5417\uff1f"},"content":{"rendered":"
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AQS \u516c\u5e73\u9501\u771f\u7684\u5b8c\u5168\u516c\u5e73\u5417\uff1f <\/h1>\n

<\/p>\n

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\u8cc7\u6df1\u5927\u4f6c : ceshi123 <\/span> <\/i> 3<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
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AQS \u4e2d\u83b7\u53d6\u516c\u5e73\u9501\u7684\u4ee3\u7801\u5982\u4e0b\uff08 jdk1.8 \uff09\uff1a protected final boolean tryAcquire(int acquires) { final Thread current = Thread.currentThread(); int c = getState(); if (c == 0) { if (!hasQueuedPredecessors() && compareAndSetState(0, acquires)) { setExclusiveOwnerThread(current); return true; } } else if (current == getExclusiveOwnerThread()) { int nextc = c + acquires; if (nextc < 0) throw new Error(“Maximum lock count exceeded”); setState(nextc); return true; } return false; } }<\/p>\n

\u5982\u679c\u6709\u4e09\u4e2a\u7ebf\u7a0b\u6765\u83b7\u53d6\u516c\u5e73\u9501\uff0c\u7b2c\u4e00\u4e2a\u7ebf\u7a0b\u83b7\u53d6\u6210\u529f\uff0c\u7b2c\u4e8c\u4e0e\u7b2c\u4e09\u4e2a\u7ebf\u7a0b\u8d70\u5230 hasQueuedPredecessors()\uff0c\u90fd\u5224\u65ad\u51fa\u4e3a false(\u6b64\u65f6\u961f\u5217\u4e3a\u7a7a\uff0c\u4ed6\u4eec\u90fd\u53ef\u4ee5\u83b7\u53d6\u9501)\uff0c\u7b2c\u4e8c\u4e2a\u7ebf\u7a0b\u7ee7\u7eed\u8d70\uff08\u7b2c\u4e09\u4e2a\u7ebf\u7a0b\u65f6\u95f4\u7247\u5230\u4e86\uff0c\u505c\u4f4f\uff09\uff0c\u83b7\u53d6\u9501\u5931\u8d25\uff08\u56e0\u4e3a\u9501\u5df2\u7ecf\u88ab\u7b2c\u4e00\u4e2a\u7ebf\u7a0b\u83b7\u53d6\u4e86\uff09\uff0c\u90a3\u5c31\u4e56\u4e56\u7684\u53bb\u6392\u961f\uff0c\u6784\u9020\u5934\u7ed3\u70b9\u4e0e\u81ea\u5df1\u7684\u8282\u70b9\uff0c\u6b64\u65f6 sync \u961f\u5217\u4e3a: head \u2192 node2\uff0cnode2 \u2192 head\uff0c\u7136\u540e\u7b2c\u4e8c\u4e2a\u7ebf\u7a0b\u53c8\u6765\u62a2\u5360\u9501\uff08\u6e90\u7801\u4e2d\u6709\u4e2a for \u5faa\u73af\uff09\uff0c\u8d70\u5230 hasQueuedPredecessors()\uff0c\u5224\u65ad\u51fa\u4e5f\u4e3a false \uff08\u56e0\u4e3a\u81ea\u5df1\u5c31\u662f\u961f\u5217\u4e2d\u7684\u7b2c\u4e8c\u4e2a\u8282\u70b9\uff0c\u662f\u6709\u8d44\u683c\u62a2\u9501\u7684\uff09\uff0c\u6b64\u65f6\u7ebf\u7a0b\u4e00\u91ca\u653e\u4e86\u9501\uff0c\u90a3\u4e48\u7b2c\u4e8c\u4e2a\u7ebf\u7a0b\u4e0e\u7b2c\u4e09\u4e2a\u7ebf\u7a0b\u540c\u65f6\u62a2\u9501\uff0c\u9501\u662f\u6709\u53ef\u80fd\u88ab\u4e09\u4e2a\u7ebf\u7a0b\u62a2\u5230\u4e86\u3002<\/p>\n

\u90a3\u4e48\u8fd9\u662f\u4e0d\u662f\u8fdd\u80cc\u4e86\u516c\u5e73\u9501\u7684\u6982\u5ff5\uff0c\u6216\u8005\u516c\u5e73\u9501\u5e76\u4e0d\u662f\u7edd\u5bf9\u7684\u516c\u5e73\uff0c\u56e0\u4e3a\u7b2c\u4e8c\u4e2a\u7ebf\u7a0b\u5df2\u7ecf\u5728\u961f\u5217\u91cc\u9762\u6392\u597d\u4e86\u961f\uff0c\u4e5f\u8be5\u662f\u81ea\u5df1\u62ff\u5230\u9501\uff0c\u7ed3\u679c\u9501\u88ab\u7b2c\u4e09\u4e2a\u7ebf\u7a0b\u62ff\u8d70\u4e86\u3002<\/p>\n

\u9ebb\u70e6\u5404\u4f4d\u5927\u795e\u89e3\u60d1\u4e00\u4e0b\uff01\uff01\uff01<\/p>\n<\/p><\/div>\n

\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (8<\/span>) <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
    \n
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    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : ceshi123 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u6211\u64e6\uff0c\u5927\u795e\u5462 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : yamasa <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u6211\u89c9\u5f97 tryAccquire \u7684\u8fd9\u4e00\u6bb5\u6ce8\u91ca\u53ef\u4ee5\u89e3\u7b54\u8fd9\u4e2a\u95ee\u9898\u4e86\uff1a<\/p>\n

    Likewise, it is possible for another thread to win a race to enqueue after this method has returned {@code false}, due to the queue being empty. <\/p><\/div>\n<\/p><\/div>\n<\/li>\n

  • \n
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    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : ceshi123 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @yamasa \u90a3\u5176\u5b9e\u5b83\u5728\u6781\u7aef\u573a\u666f\u4e0b\u662f\u5e76\u4e0d\u662f\u5b8c\u5168\u516c\u5e73\u7684 <\/div>\n<\/p><\/div>\n<\/li>\n
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    \u8cc7\u6df1\u5927\u4f6c : yamasa <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @ceshi123 \u5bf9 \u800c\u4e14\u53ef\u4ee5\u8bf4\u5bf9\u4e8e\u7edd\u5927\u90e8\u5206\u573a\u666f\uff0c\u975e\u516c\u5e73\u7684 performance \u90fd\u66f4\u597d <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : THESDZ <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5927\u90e8\u5206\u7684\u7a0b\u5e8f\u53ea\u4f1a\u8003\u8651\u7edd\u5927\u591a\u6570\u7684\u60c5\u51b5,\u56e0\u4e3a\u8981\u8003\u8651\u6240\u6709\u60c5\u51b5\u6216\u8005\u6781\u7aef\u60c5\u51b5\u7684\u8bdd,\u6210\u672c>>\u6536\u76ca <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : THESDZ <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @THESDZ #5 \u5982\u679c\u7684\u786e\u8981\u8003\u8651\u6781\u7aef\u60c5\u51b5,\u901a\u5e38\u60c5\u51b5\u662f\u901a\u8fc7”\u4e8b\u540e”\u8865\u6551 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : 1194129822 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4f60\u8fd9\u7406\u89e3\u4e0d\u5bf9\uff0c\u9996\u5148\u8bf4\u4e00\u4e0b\uff0c\u516c\u5e73\u53ea\u662f\u76f8\u5bf9\u7684\u516c\u5e73\uff0c\u6240\u6709\u516c\u5e73\u6a21\u5f0f\uff0c\u5c31\u662f\u5982\u679c\u524d\u9762\u6709\u7ebf\u7a0b\u6392\u961f\u5c31\u52a0\u5165\u961f\u5c3e\uff0c\u800c\u975e\u516c\u5e73\u6a21\u5f0f\uff0c\u5c31\u662f\u7ebf\u7a0b\u76f4\u63a5\u5c1d\u8bd5\u83b7\u53d6\u9501\uff0c\u83b7\u53d6\u5931\u8d25\u624d\u6392\u961f\u3002\u4f46\u662f\u7ebf\u7a0b\u672c\u8eab\u7684\u6267\u884c\u662f\u6ca1\u6709\u987a\u5e8f\u548c\u4f18\u5148\u7ea7\u7684\u3002\u5982\u679c\u7ebf\u7a0b 2 \u56e0\u4e3a os \u8c03\u5ea6\uff0c\u4e00\u76f4\u5f97\u4e0d\u5230\u8fd0\u884c\uff0c\u53ef\u80fd\u4e00\u76f4\u6c38\u8fdc\u6392\u961f\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : wysnylc <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u516c\u5e73\u662f\u76f8\u5bf9\u7684\u800c\u4e14\u4e0d\u540c\u7684\u89d2\u5ea6\u4e5f\u4f1a\u6709\u4e0d\u540c\u89c1\u89e3
    \u65e0\u5e8f\u7684\u4e89\u62a2\u624d\u662f\u9ad8\u6548 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"

    AQS \u516c\u5e73\u9501\u771f\u7684\u5b8c\u5168\u516c\u5e73\u5417\uff1f \u8cc7…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/200057"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=200057"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/200057\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=200057"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=200057"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=200057"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}