{"id":602,"date":"2017-03-25T13:18:08","date_gmt":"2017-03-25T05:18:08","guid":{"rendered":"http:\/\/blog.sorayuki.net\/?p=602"},"modified":"2017-03-26T16:23:22","modified_gmt":"2017-03-26T08:23:22","slug":"%e6%9d%a1%e4%bb%b6%e5%8f%98%e9%87%8f%e7%9a%84%e4%bc%aa%e5%94%a4%e9%86%92","status":"publish","type":"post","link":"https:\/\/blog.sorayuki.net\/?p=602","title":{"rendered":"\u6761\u4ef6\u53d8\u91cf\u7684\u4f2a\u5524\u9192"},"content":{"rendered":"<p>\u8d77\u56e0\u662f\u8fd9\u6837\u7684\uff0cC++\u7684\u65b0\u6807\u51c6\u5e93\u6dfb\u52a0\u4e86\u591a\u7ebf\u7a0b\u7684\u652f\u6301\uff0c\u6709\u7ebf\u7a0b\u548c\u7ebf\u7a0b\u540c\u6b65\u7684\u5b9e\u73b0\u3002\u6211\u81ea\u5df1\u662f\u505aWindows\u5f00\u53d1\u6bd4\u8f83\u591a\uff0c\u81ea\u7136\u7528\u8fc7Event\u8fd9\u6837\u7684\u7ebf\u7a0b\u540c\u6b65\u5bf9\u8c61\u3002\u4f46\u662f\u8fd9\u4e2a\u4e1c\u897f\uff0c\u5728C++\u7684\u6807\u51c6\u5e93\u91cc\u9762\u6ca1\u6709\u3002\u6211\u60f3\u5230\u8bf4\u5b83\u6709\u4e00\u4e2a\u201c\u6761\u4ef6\u53d8\u91cf\u201d\uff0c\u800c\u8fd9\u4e2a\u201c\u6761\u4ef6\u53d8\u91cf\u201d\u662f\u6709\u4e00\u4e2await \/ signal \u529f\u80fd\u7684\uff0c\u8fd9\u4e2a\u7c7b\u770b\u8d77\u6765\u80fd\u5b9e\u73b0 Event \u7684\u4e00\u90e8\u5206\u529f\u80fd\u3002\u4f46\u662f\u5728\u524d\u51e0\u5929\uff0c\u6709\u4e2a\u540c\u4e8b\u8bf4\u6761\u4ef6\u53d8\u91cf\u7684 wait \u4f1a\u5728\u6ca1\u6709\u88ab signal \u7684\u65f6\u5019\u4e5f\u81ea\u5df1\u5524\u9192\u3002\u6bd5\u7adf\u5e73\u65f6\u4e0d\u505a posix \u90a3\u6837\u7cfb\u7edf\u4e0b\u9762\u7684\u5f00\u53d1\uff0c\u6240\u4ee5\u8fd9\u6837\u7684\u4e8b\u60c5\u6ca1\u6709\u542c\u8bf4\u8fc7\u3002\u90a3\u4f1a\u513f\u5176\u5b9e\u6211\u662f\u4e0d\u4fe1\u7684\uff0c\u4f46\u662f\u7528\u5173\u952e\u5b57\u201ccondition variable fake wake\u201d\u5728\u7f51\u4e0a\u641c\u4e86\u4e00\u4e0b\u4ee5\u540e\uff0c\u770b\u5230\u786e\u5b9e\u662f\u6709\u8fd9\u6837\u7684\u4e8b\u60c5\uff0c\u7136\u540e\u82f1\u8bed\u4e2d\u4e5f\u4e0d\u662f\u53eb fake\uff0c\u7ba1\u5b83\u53eb spurious wakeup\u3002<\/p>\n<p><!--more--><\/p>\n<p>\u5728\u7f51\u4e0a\u641c\u4e86\u4e00\u5927\u5708\uff0c\u7ed3\u5408\u591a\u4e2a\u6587\u7ae0\u548c\u95ee\u7b54\u4ee5\u540e\uff0c\u5f97\u77e5\u5728\u6ca1\u6709\u5176\u4ed6\u7ebf\u7a0b\u8c03\u7528 pthread_cond_signal \u6216\u8005 pthread_cond_broadcast \u8fd9\u6837\u7684\u8c03\u7528\u7684\u60c5\u51b5\u4e0b\uff0c pthread_cond_wait \u4e5f\u53ef\u80fd\u4f1a\u63d0\u524d\u8fd4\u56de\u3002\u7a0b\u5e8f\u5458\u5728\u8c03\u7528 pthread_cond_wait \u7684\u65f6\u5019\uff0c\u8981\u51c6\u5907\u597d\u5b83\u53ef\u80fd\u5728\u6ca1\u6709\u6536\u5230\u4fe1\u53f7\u7684\u65f6\u5019\u5c31\u5df2\u7ecf\u9192\u6765\u7684\u60c5\u51b5\u3002\u901a\u5e38\u7684\u505a\u6cd5\u662f\u628a pthread_cond_wait \u653e\u5728\u4e00\u4e2a while \u5faa\u73af\u91cc\uff0c\u5faa\u73af\u7684\u6761\u4ef6\u662f\u6761\u4ef6\u53d8\u91cf\u8981\u7b49\u5f85\u7684\u6761\u4ef6\u3002\u8fd9\u6837\u5728\u4f2a\u5524\u9192\u53d1\u751f\u7684\u65f6\u5019\uff0c\u7a0b\u5e8f\u4f1a\u518d\u6b21\u68c0\u67e5\u6761\u4ef6\u662f\u5426\u6ee1\u8db3\u3002\u5982\u679c\u6761\u4ef6\u6ca1\u6709\u6ee1\u8db3\uff0c\u6267\u884c\u6d41\u7a0b\u4f1a\u8f6c\u5230\u7ee7\u7eed\u8c03\u7528 pthread_cond_wait \u90a3\u8fb9\u53bb\uff1b\u5982\u679c\u6ee1\u8db3\uff0c\u624d\u7ee7\u7eed\u6267\u884c\u3002<\/p>\n<p>\u5728Stackoverflow\u4e0a\u6211\u627e\u5230\u4e86\u8fd9\u6837\u7684\u89e3\u91ca\uff1a Linux \u4e0b\u7684mutex\uff0c\u4f7f\u7528\u4e86\u4e00\u79cd\u53eb\u505a futex \u7684\u66f4\u5e95\u5c42\u7684\u5bf9\u8c61\u6765\u5b9e\u73b0\u3002\u8fd9\u4e2a futex \u6709\u4e00\u4e2a\u95ee\u9898\uff0c\u5c31\u662f\u5728\u8fdb\u7a0b\u6536\u5230 signal \uff08<strong>\u4e0d\u662f conditional variable \u7684\u90a3\u4e2a signal\uff0c\u662f *nix \u7cfb\u7edf\u4e0b\u7528 kill \u547d\u4ee4\u53d1\u9001\u7684\u90a3\u79cd\u201c\u4fe1\u53f7\u201d<\/strong>\uff09\u7684\u65f6\u5019\uff0c\u6b63\u5728\u7b49\u5f85futex \u800c\u88ab\u6302\u8d77\u7684\u7ebf\u7a0b\uff0c\u4f1a\u88ab\u5524\u9192\u3001\u5e76\u6267\u884c signal \u7684\u5904\u7406\u51fd\u6570\u3002\u73b0\u5728\u5df2\u7ecf\u77e5\u9053\u4e86\u4ec0\u4e48\u4e00\u79cd\u80fd\u76f4\u89c2\u5730\u770b\u4f2a\u5524\u9192\u53d1\u751f\u7684\u60c5\u51b5\uff0c\u90a3\u4e48\u505a\u4e00\u4e2a\u5b9e\u9a8c\u5427\u3002<\/p>\n<pre>#include &lt;pthread.h&gt;\n#include &lt;stdio.h&gt;\n#include &lt;unistd.h&gt;\n#include &lt;signal.h&gt;\n\npthread_t mainThread;\n\nvoid sigHandler(int arg)\n{\n    const char* p;\n    if (pthread_equal(pthread_self(), mainThread))\n        p = \"the same\";\n    else\n        p = \"different\";\n    printf(\"SIGUSR1 signal received on %s thread\\n\", p);\n}\n\nint main()\n{\n    pthread_mutex_t pmutex;\n    pthread_cond_t pcond;\n\n    signal(SIGUSR1, sigHandler);\n\n    printf(\"process id: %d\\n\", getpid());\n\n    mainThread = pthread_self();\n\n    pthread_mutex_init(&amp;pmutex, 0);\n    pthread_cond_init(&amp;pcond, 0);\n    pthread_mutex_lock(&amp;pmutex);\n    pthread_cond_wait(&amp;pcond, &amp;pmutex);\n    puts(\"wake up!\");\n    pthread_mutex_unlock(&amp;pmutex);\n    return 0;\n}\n<\/pre>\n<p>\u5f88\u663e\u7136\uff0c\u8fd9\u4ee3\u7801\u91cc\u9762\u56e0\u4e3a\u53ea\u6709\u4e00\u4e2a\u7ebf\u7a0b\u5728\u8dd1\uff0c\u6240\u4ee5\u6c38\u8fdc\u6ca1\u4eba\u4f1a\u53bb\u5524\u9192 pthread_cond_wait \u7684\u7b49\u5f85\u3002\u4f46\u662f\u6839\u636e\u4e0a\u9762\u90a3\u4e9b\u7f51\u4e0a\u8c03\u67e5\u6240\u5f97\u6765\u7684\u4fe1\u606f\uff0c\u6240\u671f\u671b\u7684\u7ed3\u679c\u662f\u5728\u6709signal\u90a3\u6837\u7684\u4fe1\u53f7\u53d1\u6765\u7684\u65f6\u5019\uff0c \u7ebf\u7a0b\u4f1a\u88ab\u5524\u9192\uff0c\u4e8e\u662f\u5c31\u5728\u7a0b\u5e8f\u91cc\u6ce8\u518c\u4e86\u4e00\u4e2asignal\u5904\u7406\u51fd\u6570\uff0c\u5728\u4fe1\u53f7\u6765\u7684\u65f6\u5019\u4f1a\u8f93\u51fa\u4fe1\u606f\u5e76\u5224\u65ad\u6267\u884c\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u7684\u7ebf\u7a0b\u662f\u4e0d\u662f\u4e3b\u7ebf\u7a0b\uff0c\u7136\u540e\u8f93\u51fa\u662f\u4e0d\u662f\u5728\u4e3b\u7ebf\u7a0b\u6536\u5230\u4fe1\u53f7\u7684\u4fe1\u606f\uff0c\u7136\u540epthread_cond_wait\u8fd4\u56de\uff0c\u7a0b\u5e8f\u8f93\u51fa wake up! \u4fe1\u606f\u540e\u9000\u51fa\u3002<\/p>\n<p>\u56e0\u4e3a\u7a0b\u5e8f\u7528\u5230\u4e86 pthread \u6240\u4ee5\u7f16\u8bd1\u7684\u65f6\u5019\u8981\u5e26\u4e0a -lpthread \u53c2\u6570\u3002\u6211\u5728\u865a\u62df\u673a\u91cc\u9762\u7f16\u8bd1\u8fd0\u884c\u8fd9\u4e2a\u7a0b\u5e8f\uff0c\u7136\u540e\u7528 kill -SIGUSR1 \u7ed9\u5b83\u53d1\u4fe1\u53f7\uff0c\u7ed3\u679c\u770b\u5230\u4e86\u8fd9\u6837\u7684\u8f93\u51fa\u3002<\/p>\n<p><a href=\"https:\/\/blog.sorayuki.net\/wp-content\/uploads\/2017\/03\/screenshot1.jpg\"><img loading=\"lazy\" decoding=\"async\" title=\"screenshot1\" style=\"border-left-width: 0px; border-right-width: 0px; background-image: none; border-bottom-width: 0px; padding-top: 0px; padding-left: 0px; display: inline; padding-right: 0px; border-top-width: 0px\" border=\"0\" alt=\"screenshot1\" src=\"https:\/\/blog.sorayuki.net\/wp-content\/uploads\/2017\/03\/screenshot1_thumb.jpg\" width=\"391\" height=\"138\"><\/a> <\/p>\n<p>\u4e0e\u6240\u671f\u671b\u7684\u7ed3\u679c\u4e00\u81f4\u3002 <\/p>\n<p>\u90a3\u4e48\u73b0\u5728\u95ee\u9898\u662f\uff0c\u8fd9\u4e2a pthread_cond_wait \u5b83\u4e3a\u4ec0\u4e48\u88ab\u5524\u9192\u7136\u540e\u53d1\u73b0\u4e0d\u662f pthread_cond_signal \u505a\u7684\u540e\uff0c\u662f\u8fd4\u56de\u800c\u4e0d\u662f\u7ee7\u7eed\u56de\u53bb\u7b49\u5f85\u5462\uff1f <\/p>\n<p>\u5728 pthread_cond_signal \u51fd\u6570\u7684\u8bf4\u660e\u91cc\uff0c\u6709\u8fd9\u4e48\u6837\u7684\u63cf\u8ff0 <\/p>\n<blockquote>\n<p>The <i>pthread_cond_broadcast<\/i>() and <i>pthread_cond_signal<\/i>() functions shall have no effect if there are no threads currently blocked on <i>cond<\/i>.<\/p>\n<\/blockquote>\n<p>\u4e5f\u5c31\u662f\u8bf4\uff0c\u5982\u679c\u5f53\u524d\u6ca1\u6709\u7ebf\u7a0b\u6b63\u5728\u7b49\u5f85\uff0c\u90a3\u4e48\u5c31\u6ca1\u6548\u679c\u3002\u8fd9\u4e2a\u548cWindows\u4e0b\u7684\u624b\u52a8\u91cd\u7f6e\u4e8b\u4ef6\u662f\u4e0d\u4e00\u6837\u7684\u3002 <\/p>\n<p>\u7ed3\u5408\u524d\u9762\u8bf4\u7684\uff0c\u4fe1\u53f7\u6765\u7684\u65f6\u5019\u7ebf\u7a0b\u4f1a\u88ab\u5524\u9192\uff0c\u90a3\u4e48\u8fd9\u4e2a\u7ebf\u7a0b\u6b64\u65f6\u5c31\u4e0d\u5728 blocked \u72b6\u6001\u3002\u56e0\u4e3a\u5728 pthread_cond_wait \u7b49\u5f85\u7684\u65f6\u5019\uff0c\u548c\u6761\u4ef6\u53d8\u91cf\u4e00\u8d77\u4f7f\u7528\u7684\u9501\u662f\u88ab\u91ca\u653e\u7684\uff0c\u6240\u4ee5\u5176\u4ed6\u7ebf\u7a0b\u5728\u8fd9\u6bb5\u65f6\u95f4\u91cc\u662f\u53ef\u4ee5\u62ff\u5230\u9501\u3001\u4fee\u6539\u6761\u4ef6\u53d8\u91cf\u7684\u7b49\u5f85\u6761\u4ef6\u3001\u5e76\u4e14\u8c03\u7528 pthread_cond_signal \u7684\uff1b\u4f46\u6b64\u65f6\u8c03\u7528 pthread_cond_wait \u7684\u7ebf\u7a0b\u56e0\u4e3a\u4e0d\u662f blocked \u72b6\u6001\uff0c\u6240\u4ee5 pthread_cond_signal \u7684\u8c03\u7528\u5176\u5b9e\u6ca1\u6709\u4ea7\u751f\u6548\u679c\u3002\u5982\u679c pthread_cond_wait \u51fd\u6570\u4e0d\u518d\u6b21\u68c0\u67e5\u6761\u4ef6\u3001\u800c\u662f\u76f4\u63a5\u56de\u53bb\u7b49\u5f85\uff0c\u90a3\u4e48\u5c31\u9519\u8fc7\u4e86\u8fd9\u6b21\u673a\u4f1a\uff0c\u8fd8\u6709\u53ef\u80fd\u56e0\u6b64\u9020\u6210\u6b7b\u9501\uff08\u56e0\u4e3a\u76f8\u5f53\u4e8e\u6ca1\u901a\u77e5\u5230\uff09\u3002<\/p>\n<pre><p>\u7ebf\u7a0b1\uff1a---mutex\u4e0a\u9501---------------\u68c0\u67e5\u6761\u4ef6\u4e0d\u6ee1\u8db3-------\u7b49\u5f85-----------------------------<\/p><p>      -----\u88abkill\u53d1\u7684\u4fe1\u53f7\u5524\u9192------------------\uff08\u6b64\u65f6\u5e94\u8be5\u505a\u4ec0\u4e48\uff1f\uff09--------<\/p><p>\n\u7ebf\u7a0b2\uff1a-------------\u5c1d\u8bd5\u9501mutex----------------------------\u9501mutex\u6210\u529f----\u6539\u53d8\u4e86\u68c0\u67e5\u6761\u4ef6-<\/p><p>      ---------------------pthread_cond_signal---\u89e3\u9501mutex------------\n<\/p><\/pre>\n<p>\u4ee5\u4e0a\u793a\u4f8b\u4e2d\uff0c\u7ebf\u7a0b1\u56e0\u4e3a kill \u7684\u4fe1\u53f7\u800c\u9519\u8fc7\u4e86 pthread_cond_signal \u7684\u4fe1\u53f7\uff0c\u5982\u679c\u7ee7\u7eed\u56de\u53bb\u7b49\u5f85\u3002\u90a3\u4e48\u53ef\u80fd\u5c31\u518d\u4e5f\u6ca1\u673a\u4f1a\u9192\u8fc7\u6765\u4e86\u3002<\/p>\n<p>\u6240\u4ee5\u6761\u4ef6\u53d8\u91cf\u7684\u4f7f\u7528\u65b9\u5f0f\u662f\u8fd9\u4e48\u8bbe\u8ba1\u7684\uff1a\u5148\u52a0\u9501\uff0c\u7136\u540e\u4e00\u4e2awhile\u5faa\u73af\uff0c\u5982\u679c\u6761\u4ef6\u4e0d\u6ee1\u8db3\u90a3\u4e48\u5c31\u5728\u6761\u4ef6\u53d8\u91cf\u4e0a\u7b49\u5f85\uff0c\u7b49\u5f85\u7ed3\u675f\u4e4b\u540e\u518d\u6b21\u68c0\u67e5\u6761\u4ef6\u662f\u4e0d\u662f\u6ee1\u8db3\uff1a\u56e0\u4e3a\u5982\u679c\u4f2a\u5524\u9192\u53d1\u751f\u4e86\uff0c\u90a3\u4e48\u8fd9\u4e2a\u65f6\u5019\u6761\u4ef6\u5176\u5b9e\u662f\u4e0d\u6ee1\u8db3\u7684\u3002<\/p>\n<p>\u53c2\u8003\uff1a<\/p>\n<p><a title=\"http:\/\/stackoverflow.com\/questions\/21411912\/what-can-wake-up-a-conditional-variable\" href=\"http:\/\/stackoverflow.com\/questions\/21411912\/what-can-wake-up-a-conditional-variable\">http:\/\/stackoverflow.com\/questions\/21411912\/what-can-wake-up-a-conditional-variable<\/a><br \/><a title=\"http:\/\/man7.org\/linux\/man-pages\/man2\/futex.2.html\" href=\"http:\/\/man7.org\/linux\/man-pages\/man2\/futex.2.html\">http:\/\/man7.org\/linux\/man-pages\/man2\/futex.2.html<\/a><br \/><a title=\"https:\/\/linux.die.net\/man\/3\/pthread_cond_signal\" href=\"https:\/\/linux.die.net\/man\/3\/pthread_cond_signal\">https:\/\/linux.die.net\/man\/3\/pthread_cond_signal<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u8d77\u56e0\u662f\u8fd9\u6837\u7684\uff0cC++\u7684\u65b0\u6807\u51c6\u5e93\u6dfb\u52a0\u4e86\u591a\u7ebf\u7a0b\u7684\u652f\u6301\uff0c\u6709\u7ebf\u7a0b\u548c\u7ebf\u7a0b\u540c\u6b65\u7684\u5b9e\u73b0\u3002\u6211\u81ea\u5df1\u662f\u505aWindows\u5f00\u53d1\u6bd4\u8f83\u591a\uff0c &hellip; <a href=\"https:\/\/blog.sorayuki.net\/?p=602\" class=\"more-link\">\u7ee7\u7eed\u9605\u8bfb<span class=\"screen-reader-text\">\u6761\u4ef6\u53d8\u91cf\u7684\u4f2a\u5524\u9192<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[],"class_list":["post-602","post","type-post","status-publish","format-standard","hentry","category-23"],"_links":{"self":[{"href":"https:\/\/blog.sorayuki.net\/index.php?rest_route=\/wp\/v2\/posts\/602","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.sorayuki.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.sorayuki.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.sorayuki.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.sorayuki.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=602"}],"version-history":[{"count":0,"href":"https:\/\/blog.sorayuki.net\/index.php?rest_route=\/wp\/v2\/posts\/602\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.sorayuki.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=602"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.sorayuki.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=602"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.sorayuki.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=602"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}