{"id":123,"date":"2021-09-29T21:48:32","date_gmt":"2021-09-29T13:48:32","guid":{"rendered":"https:\/\/www.xudongvp.com\/?p=123"},"modified":"2021-09-29T21:48:34","modified_gmt":"2021-09-29T13:48:34","slug":"%e6%93%8d%e4%bd%9c%e7%b3%bb%e7%bb%9f%ef%bc%9a%e4%bf%a1%e5%8f%b7%e9%87%8f%e4%b8%8epv%e5%8e%9f%e8%af%ad","status":"publish","type":"post","link":"https:\/\/www.xudongvp.com\/?p=123","title":{"rendered":"\u64cd\u4f5c\u7cfb\u7edf\uff1a\u4fe1\u53f7\u91cf\u4e0ePV\u539f\u8bed"},"content":{"rendered":"\n

\u4e00\u3001\u4fe1\u53f7\u91cf\u7684\u63d0\u51fa<\/h2>\n\n\n\n

1965 \u5e74\uff0c\u8377\u5170\u5b66\u8005Dijkstra \u63d0\u51fa\u7684\u4fe1\u53f7\u91cf(Semaphores)\u673a\u5236\u662f\u4e00\u79cd\u5353\u6709\u6210\u6548\u7684\u8fdb\u7a0b\u540c\u6b65\u5de5\u5177\u3002\u5728\u957f\u671f\u4e14\u5e7f\u6cdb\u7684\u5e94\u7528\u4e2d\uff0c\u4fe1\u53f7\u91cf\u673a\u5236\u53c8\u5f97\u5230\u4e86\u5f88\u5927\u7684\u53d1\u5c55\uff0c\u5b83\u4ece\u6574\u578b\u4fe1\u53f7\u91cf\u7ecf\u8bb0\u5f55\u578b\u4fe1\u53f7\u91cf\uff0c\u8fdb\u800c\u53d1\u5c55\u4e3a\u201c\u4fe1\u53f7\u91cf\u96c6\u201d\u673a\u5236\u3002\u73b0\u5728\uff0c\u4fe1\u53f7\u91cf\u673a\u5236\u5df2\u88ab\u5e7f\u6cdb\u5730\u5e94\u7528\u4e8e\u5355\u5904\u7406\u673a\u548c\u591a\u5904\u7406\u673a\u7cfb\u7edf\u4ee5\u53ca\u8ba1\u7b97\u673a\u7f51\u7edc\u4e2d\u3002<\/p>\n\n\n\n

\u4e8c\u3001\u4fe1\u53f7\u91cf\u7684\u539f\u5b50\u64cd\u4f5c<\/h2>\n\n\n\n

\u8981\u51c6\u786e\u7406\u89e3\u4fe1\u53f7\u91cf\u7684\u4e24\u4e2a\u539f\u5b50\u64cd\u4f5cPV\uff0c\u6709\u51e0\u4e2a\u95ee\u9898\u662f\u7ed5\u4e0d\u8fc7\u7684\uff0c\u7b2c\u4e00\uff0cPV\u4e3a\u4ec0\u4e48\u53ebPV\uff1f\u7b2c\u4e8c\uff0cPV\u6240\u9488\u5bf9\u7684\u4fe1\u53f7\u91cf\u7c7b\u578b\u652f\u6301\u4ec0\u4e48\u6837\u7684\u80fd\u529b\u3002<\/p>\n\n\n\n

\u5728\u7b2c\u4e00\u7ae0\u65f6\u6211\u4eec\u63d0\u5230\uff0c\u4fe1\u53f7\u91cf\u4ee5\u53ca\u5176\u673a\u5236\u662f\u8377\u5170\u5b66\u8005Dijkstra\u63d0\u51fa\u7684\uff0cP\u548cV\u662f\u6765\u6e90\u4e8e\u4e24\u4e2a\u8377\u5170\u8bed\u8bcd\u6c47\uff0cP\uff1apasseren\uff0c\u4e2d\u6587\u8bd1\u4e3a”\u901a\u8fc7”\uff1bV\uff1avrijgeven\uff0c\u4e2d\u6587\u8bd1\u4e3a”\u91ca\u653e”\u3002\u77e5\u9053\u8fd9\u4e8b\u60c5\uff0c\u6211\u4eec\u5c31\u4e0d\u5fc5\u518d\u7ea0\u7ed3\u4e0e\u64cd\u4f5c\u7cfb\u7edf\u6559\u6750\u4e2d\u4e3a\u4f55\u8bf4P\u662fWait\uff0cV\u662fSignal\uff0c\u4e4d\u4e00\u770b\u592a\u641e\u7b11\u4e86\u3002\u7406\u89e3\u4e86PV\u7684\u539f\u59cb\u542b\u4e49\uff0c\u90a3\u6211\u4eec\u540e\u9762\u628aPV\u6539\u6210WS\u7684\u65f6\u5019\uff0c\u8bf7\u5404\u4f4d\u4e5f\u4e0d\u8981\u89c1\u602a\u3002<\/p>\n\n\n\n

\u7b2c\u4e8c\uff0c\u4fe1\u53f7\u91cf\u7684\u7c7b\u578b\u3002\u6700\u521d\u57fa\u7840\u7684\u6574\u5f62\u4fe1\u53f7\u91cf\uff0c\u5b9e\u9645\u4e0a\u662f\u4e0d\u80fd\u5b8c\u7f8e\u7684\u5b9e\u73b0\u4fe1\u53f7\u91cf\u673a\u5236\u7684\uff0c\u5728\u6574\u578b\u4fe1\u53f7\u91cf\u673a\u5236\u4e2d\u7684wait\u64cd\u4f5c\uff0c\u53ea\u8981\u662f\u4fe1\u53f7\u91cfS\u22640\uff0c\u5c31\u4f1a\u4e0d\u65ad\u5730\u6d4b\u8bd5\u3002\u56e0\u6b64\uff0c\u8be5\u673a\u5236\u5e76\u672a\u9075\u5faa\u201c\u8ba9\u6743\u7b49\u5f85\u201d\u7684\u51c6\u5219\uff0c\u800c\u662f\u4f7f\u8fdb\u7a0b\u5904\u4e8e\u201c\u5fd9\u7b49\u201d\u7684\u72b6\u6001\u3002\u57fa\u4e8e\u6574\u5f62\u4fe1\u53f7\u91cf\u7684\u6539\u8fdb\u578b\uff1a\u8bb0\u5f55\u578b\u4fe1\u53f7\u91cf\uff0c\u4fe1\u53f7\u91cf\u5bf9\u8c61\u4e2d\uff0c\u4f1a\u6709\u4e24\u4e2a\u6570\u636e\u9879\uff1a1\uff09\u8868\u793a\u8d44\u6e90\u6570\u76ee\u7684\u6574\u5f62\u53d8\u91cf\uff0c2\uff09\u8fdb\u7a0b\u94fe\u8868\u6307\u9488\uff0c\u7528\u4e8e\u94fe\u63a5\u6240\u6709\u7684\u7b49\u5f85\u8fdb\u7a0b\u3002<\/p>\n\n\n\n

type semaphore=record<\/p>\n\n\n\n

value: integer\uff1b<\/p>\n\n\n\n

L: list of process\uff1b<\/p>\n\n\n\n

end<\/p>\n\n\n\n

\u5728\u6b64\u57fa\u7840\u4e0a\uff0cwait(S)\u548csignal(S)\u64cd\u4f5c\u53ef\u63cf\u8ff0\u4e3a\uff1a<\/p>\n\n\n\n

procedure wait(S)<\/p>\n\n\n\n

var S\uff1asemaphore\uff1b<\/p>\n\n\n\n

begin<\/p>\n\n\n\n

S.value:=S.value-1\uff1b<\/p>\n\n\n\n

if S.value<0 then block(S.L)\uff1b<\/p>\n\n\n\n

end<\/p>\n\n\n\n

procedure signal(S)<\/p>\n\n\n\n

var S: semaphore\uff1b<\/p>\n\n\n\n

begin<\/p>\n\n\n\n

S.value:=S.value+1\uff1b<\/p>\n\n\n\n

if S.value<=0 then wakeup(S.L)\uff1b<\/p>\n\n\n\n

end<\/p>\n\n\n\n

\u4e09\u3001\u4fe1\u53f7\u91cf\u6765\u5b9e\u73b0\u524d\u8d8b\u5173\u7cfb<\/h2>\n\n\n\n

\u53ef\u5229\u7528\u4fe1\u53f7\u91cf\u6765\u63cf\u8ff0\u7a0b\u5e8f\u6216\u8bed\u53e5\u4e4b\u95f4\u7684\u524d\u8d8b\u5173\u7cfb\u3002\u8bbe\u6709\u4e24\u4e2a\u5e76\u53d1\u6267\u884c\u7684\u8fdb\u7a0bP1\u548cP2\u3002P1\u4e2d\u6709\u8bed\u53e5S1\uff1bP2\u4e2d\u6709\u8bed\u53e5S2\u3002\u6211\u4eec\u5e0c\u671b\u5728S1\u6267\u884c\u540e\u518d\u6267\u884cS2\u3002\u4e3a\u5b9e\u73b0\u8fd9\u79cd\u524d\u8d8b\u5173\u7cfb\uff0c\u6211\u4eec\u53ea\u987b\u4f7f\u8fdb\u7a0bP1\u548cP2\u5171\u4eab\u4e00\u4e2a\u516c\u7528\u4fe1\u53f7\u91cfS\uff0c\u5e76\u8d4b\u4e88\u5176\u521d\u503c\u4e3a0\uff0c\u5c06signal(S)\u64cd\u4f5c\u653e\u5728\u8bed\u53e5S1\u540e\u9762\uff1b\u800c\u5728S2\u8bed\u53e5\u524d\u9762\u63d2\u5165wait(S)\u64cd\u4f5c\uff0c\u5373\u5728\u8fdb\u7a0bP1\u4e2d\uff0c\u7528S1\uff1bsignal(S)\uff1b\u5728\u8fdb\u7a0bP2\u4e2d\uff0c\u7528wait(S)\uff1bS2\uff1b\u7531\u4e8eS\u88ab\u521d\u59cb\u5316\u4e3a0\uff0c\u8fd9\u6837\uff0c\u82e5P2\u5148\u6267\u884c\u5fc5\u5b9a\u963b\u585e\uff0c\u53ea\u6709\u5728\u8fdb\u7a0bP1\u6267\u884c\u5b8cS1\uff1bsignal(S)\uff1b\u64cd\u4f5c\u540e\u4f7fS\u589e\u4e3a1\u65f6\uff0cP2 \u8fdb\u7a0b\u65b9\u80fd\u6267\u884c\u8bed\u53e5S2 \u6210\u529f\u3002<\/p>\n\n\n\n

\u5728\u4f7f\u7528\u4fe1\u53f7\u91cf\u6765\u63a7\u5236\u7a0b\u5e8f\u6216\u8005\u8bed\u53e5\u4e4b\u524d\u7684\u524d\u8d8b\u5173\u7cfb\u65f6\uff0c\u6bcf\u6bb5\u7a0b\u5e8f\u6267\u884c\u524d\u540e\uff0c\u4f1a\u64cd\u4f5c\u4fe1\u53f7\u91cf\uff0c\u6ee1\u8db3\u81ea\u5df1\u7684Wait\u6761\u4ef6\u65f6\uff0c\u5f00\u59cb\u672c\u6bb5\u7a0b\u5e8f\u7684\u6267\u884c\uff0c\u6267\u884c\u5b8c\u6210\u540e\uff0c\u5bf9\u4f9d\u8d56\u672c\u6bb5\u7a0b\u5e8f\u7684\u4fe1\u53f7\u91cf\u6267\u884csignal\u64cd\u4f5c\u3002<\/p>\n\n\n\n

\u56db\u3001\u5df2\u77e5\u524d\u8d8b\u56fe\u5982\u4f55\u8bbe\u8ba1\u4fe1\u53f7\u91cf<\/h2>\n\n\n\n

\u5df2\u77e5\u5982\u4e0b\u524d\u8d8b\u56fe\uff1a<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

\u95ee\u9898\uff1a\u9700\u8981\u8bbe\u7f6e\u51e0\u4e2a\u4fe1\u53f7\u91cf\uff1f\u5206\u522b\u5982\u4f55\u63a7\u5236\uff0c\u624d\u80fd\u5b9e\u73b0\u6b64\u524d\u8d8b\u56fe\u3002<\/p>\n\n\n\n

\u63a8\u7406\uff1a\u4ece\u524d\u9762\u4fe1\u53f7\u91cf\u5e94\u7528\u4e8e\u524d\u8d8b\u56fe\u7684\u4ecb\u7ecd\u53ef\u77e5\uff0c\u4fe1\u53f7\u91cf\u63a7\u5236\u7684\u7a0b\u5e8f\u7684\u8fdb\u5165\u4e0e\u9000\u51fa\uff0c\u6211\u4eec\u6765\u770b\u56fe\u4e2d\uff0c\u4ee3\u8868\u7a0b\u5e8f\u7684\u8fdb\u5165\u4e0e\u9000\u51fa\u7684\uff0c\u662f\u5404\u8fdb\u7a0b\u8282\u70b9\u4e4b\u95f4\u7684\u8fde\u63a5\u7ebf\u3002\u5219\u6211\u4eec\u5c06\u6bcf\u6bb5\u8fde\u63a5\u7ebf\uff0c\u8bbe\u5b9a\u4e3a\u4e00\u4e2a\u4fe1\u53f7\u91cf\u3002\u5982\u4e0b\u56fe\uff1a<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

\u57fa\u4e8e\u6b64\u65b9\u5f0f\u8bbe\u7f6e\u4e865\u4e2a\u4fe1\u53f7\u91cfS1~S5\u3002\u90a3\u6211\u4eec\u6765\u770b\u4e00\u4e0b\u6bcf\u4e2a\u8fdb\u7a0b\u8981\u5e72\u7684\u4e8b\u60c5\u3002\u5728\u63cf\u8ff0\u4e4b\u524d\uff0c\u6211\u4eec\u7528\u6807\u51c6\u7684\u4fe1\u53f7\u91cf\u63a7\u5236\u6bb5\u65b9\u5f0f\u6765\u58f0\u660e\u4e00\u4e2a\u8fdb\u7a0b\u7684\u5de5\u4f5c\u6a21\u578b\uff0cWPS\u6a21\u578b\uff0cW\u7b49\u5f85\u6240\u9700\u8981\u7684\u524d\u7f6e\u6761\u4ef6\uff0cP\u5904\u7406\u8fdb\u7a0b\u5de5\u4f5c\uff0cS\u8bbe\u7f6e\u9700\u8981\u91ca\u653e\u7684\u6761\u4ef6\u4fe1\u53f7\u91cf\u3002<\/p>\n\n\n\n

\u5219P1\uff1aW\uff08NULL\uff09-P\uff08ANY\uff09-S\uff08S1\uff0cS2\uff09<\/p>\n\n\n\n

\u5219P2\uff1aW\uff08S1\uff0cS3\uff09-P\uff08ANY\uff09-S\uff08S4\uff09<\/p>\n\n\n\n

\u5219P3\uff1aW\uff08S2\uff09-P\uff08ANY\uff09-S\uff08S3\uff0cS5\uff09<\/p>\n\n\n\n

\u5219P4\uff1aW\uff08S4\uff0cS5\uff09-P\uff08ANY\uff09-S\uff08NULL\uff09<\/p>\n\n\n\n

\u8fd9\u6b21\u6e05\u6670\u4e86\u5427\u3002<\/p>\n\n\n\n

\u7efc\u8ff0\uff1a<\/p>\n\n\n\n

\u5e94\u7528\u4fe1\u53f7\u91cf\u5b9e\u73b0\u524d\u8d8b\u56fe\u7684\u5173\u952e\u70b9\uff1a\u7b2c\u4e00\uff0c\u7406\u89e3\u4fe1\u53f7\u91cf\u662f\u7528\u6765\u63a7\u5236\u7a0b\u5e8f\u6bb5\u7684\uff0c\u5219PV\u5206\u522b\u5728\u7a0b\u5e8f\u5f00\u59cb\u4e0e\u7a0b\u5e8f\u7ed3\u675f\u64cd\u4f5c\u3002\u7b2c\u4e8c\uff1a\u4fe1\u53f7\u91cf\u7684\u8bbe\u7f6e\u65b9\u5f0f\uff0c\u7b80\u5355\u4e00\u70b9\uff0c\u662f\u5c06\u524d\u8d8b\u56fe\u7684\u6bcf\u4e2a\u7ebf\u6bb5\uff0c\u8bbe\u7f6e\u4e3a\u4e00\u4e2a\u4fe1\u53f7\u91cf\u3002\u7136\u540e\u4f7f\u7528WPS\u6a21\u578b\uff0c\u9010\u4e2a\u5199\u51fa\u8fdb\u7a0b\u7684\u63a7\u5236\u903b\u8f91\u3002\u5b8c\u6bd5\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

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