{"id":1213,"date":"2010-08-26T11:56:20","date_gmt":"2010-08-26T03:56:20","guid":{"rendered":"http:\/\/edsionte.com\/techblog\/?p=1213"},"modified":"2010-09-24T13:47:24","modified_gmt":"2010-09-24T05:47:24","slug":"%e4%bf%a1%e5%8f%b7%e9%87%8f%e9%9b%86%e5%ae%9e%e7%8e%b0%e8%bf%9b%e7%a8%8b%e4%ba%92%e6%96%a5","status":"publish","type":"post","link":"http:\/\/edsionte.com\/techblog\/archives\/1213","title":{"rendered":"\u4fe1\u53f7\u91cf\u96c6\u5b9e\u73b0\u8fdb\u7a0b\u4e92\u65a5"},"content":{"rendered":"<p>\u672c\u6587\u4e3a\u5927\u5bb6\u5448\u73b0\u7684\u4ee3\u7801\u53ef\u4ee5\u5b9e\u73b0\u8fdb\u7a0b\u7684\u4e92\u65a5\u3002\u4e0b\u9762\u4ee3\u7801\u7701\u53bb\u4e86pv\u64cd\u4f5c\u7684\u7684\u5177\u4f53\u5b9a\u4e49\u4ee5\u53caunion semun\u7684\u5b9a\u4e49\uff08\u53ef\u53c2\u8003\u524d\u6587\uff09\u3002\u672c\u7a0b\u5e8f\u524d\u534a\u90e8\u5206\u662f\u4e00\u4e9b\u521d\u59cb\u5316\u5de5\u4f5c\uff1a\u751f\u6210key\uff0c\u521b\u5efa\u4fe1\u53f7\u91cf\u96c6\uff0c\u8bbe\u7f6e\u4fe1\u53f7\u91cf\u521d\u503c\u3002\u63a5\u4e0b\u6765\u7684\u4ee3\u7801\u4f9d\u6b21\u751f\u6210N\u4e2a\u5b50\u8fdb\u7a0b\uff0c\u5177\u4f53\u6570\u76ee\u7531\u8fd0\u884c\u65f6\u7684\u53c2\u6570\u51b3\u5b9a\u3002<\/p>\n<p>\u73b0\u5728\u6211\u4eec\u8981\u5173\u6ce8\u7684\u662f\uff0c\u8fd9\u51e0\u4e2a\u5b50\u8fdb\u7a0b\u5982\u4f55\u4e92\u65a5\u7684\u8bbf\u95ee\u4e34\u754c\u533a\uff1f\u8fd9\u662f\u672c\u95ee\u8981\u8bf4\u660e\u7684\u91cd\u70b9\u3002\u8bf7\u5148\u770b\u672c\u7a0b\u5e8f\u52a0PV\u64cd\u4f5c\u548c\u4e0d\u52a0PV\u64cd\u4f5c\u7684\u7ed3\u679c\uff1a<\/p>\n<pre class=\"brush:c\">edsionte@edsionte-laptop:~\/code\/IPC$ .\/pv 3\r\n===process 2164 enter the critical section===\r\n===process:2164 is accessing=================\r\n===process 2164 leave the critical section===\r\n===process 2165 enter the critical section===\r\n===process:2165 is accessing=================\r\n===process 2165 leave the critical section===\r\n===process 2166 enter the critical section===\r\n===process:2166 is accessing=================\r\n===process 2166 leave the critical section===\r\n\/\/\u4e0d\u52a0PV\r\n===process 2175 enter the critical section===\r\n===process 2176 enter the critical section===\r\n===process 2177 enter the critical section===\r\n===process:2177 is accessing=================\r\n===process:2176 is accessing=================\r\n===process:2175 is accessing=================\r\n===process 2176 leave the critical section===\r\n===process 2177 leave the critical section===\r\n===process 2175 leave the critical section===<\/pre>\n<p>\u53ef\u4ee5\u770b\u5230\u52a0\u5165pv\u64cd\u4f5c\u540e\uff0c\u5b50\u8fdb\u7a0b\u5728\u8bbf\u95ee\u4e34\u754c\u533a\u65f6\u90fd\u4e0d\u53d7\u5b50\u5176\u4ed6\u8fdb\u7a0b\u7684\u5f71\u54cd\u3002<\/p>\n<p>\u53ef\u662f\u4ed4\u7ec6\u60f3\u4e00\u4e0b\uff0c\u8fd9\u4e2a\u7a0b\u5e8f\u771f\u7684\u662f\u5728\u6f14\u793a\u591a\u4e2a\u8fdb\u7a0b\u4e92\u65a5\u8bbf\u95ee\u540c\u4e00\u4e2a\u4e34\u754c\u533a\u5417\uff1f\u5f53\u7136\u4e0d\u662f\uff0c\u5176\u5b9e\u4ece\u7a0b\u5e8f\u4e2d\u7684fork\u51fd\u6570\u5c31\u53ef\u4ee5\u53d1\u73b0\u3002\u56e0\u4e3afork\u540e\u7684\u5b50\u8fdb\u7a0b\u4ee3\u7801\u6bb5\uff0c\u6570\u636e\u6bb5\u7b49\u90fd\u662f\u7236\u8fdb\u7a0b\u7684\u526f\u672c\uff0c\u56e0\u6b64\u4e0b\u9762\u7684\u7a0b\u5e8f\u6839\u672c\u4e0d\u5b58\u5728\u6240\u8c13\u7684\u591a\u4e2a\u8fdb\u7a0b\u540c\u65f6\u8bbf\u95ee\u4e00\u4e2a\u4e34\u754c\u533a\u3002\u5176\u5b9e\u5c31\u662f\u6bcf\u4e2a\u8fdb\u7a0b\u5728\u5531\u81ea\u5df1\u7684\u72ec\u89d2\u620f\uff08<strong>\u5404\u8fdb\u7a0b\u8bbf\u95ee\u5c5e\u4e8e\u81ea\u5df1\u7684\u4e34\u754c\u533a\uff0c\u4e00\u5bf9\u4e00<\/strong>\uff09\u800c\u5df2\u3002<\/p>\n<p>\u4f46\u662f\uff0c\u53e6\u4e00\u4e2a\u4e8b\u5b9e\u53c8\u6446\u5728\u6211\u4eec\u9762\u524d\uff1a\u5982\u679c\u4e0d\u52a0PV\uff0c\u90a3\u4e48\u5f88\u660e\u663e\u6bcf\u4e2a\u8fdb\u7a0b\u8bbf\u95ee\u4e34\u754c\u533a\u53c8\u662f\u4ea4\u4e92\u8fd0\u884c\u7684\u3002\u5176\u5b9e\u6211\u4eec\u53ef\u4ee5\u8fd9\u6837\u60f3\uff0c\u5bf9\u4e8e\u5355\u4e2a\u5b50\u8fdb\u7a0bA\u800c\u8a00\uff0c\u5373\u4fbf\u6ca1\u6709\u5176\u4ed6\u8fdb\u7a0b\u8981\u7ade\u4e89A\u8fdb\u7a0b\u8981\u8bbf\u95ee\u7684\u90a3\u4e2a\u4e34\u754c\u533a\uff0c\u90a3\u4e48A\u8fdb\u7a0b\u8981\u4e5f\u8981\u88c5\u4f5c\u5468\u56f4\u6709\u5f88\u591a\u8fdb\u7a0b\u90a3\u6837\u2014\u2014\u5728\u8bbf\u95ee\u4e34\u754c\u533a\u7684\u65f6\u5019\u4e0d\u53d7\u5176\u4ed6\u8fdb\u7a0b\u7684\u5e72\u6270\u2014\u2014\u53ea\u4e0d\u8fc7A\u8fdb\u7a0b\u73b0\u5728\u53ea\u662f\u72ec\u81ea\u4e00\u4eba\u53bb\u9075\u5b88\u90a3\u4e2a\u89c4\u5219\u800c\u5df2\u3002\u6211\u4eec\u53ef\u4ee5\u5728V\u64cd\u4f5c\u540e\u518d\u52a0\u4e00\u53e5\u8bdd\uff1a<\/p>\n<pre class=\"brush:c\">\t\t\tsleep(2);\r\n\t\t\tprintf(\"===process %d is doing another thing=======\\n\",getpid());<\/pre>\n<p>\u518d\u6b21\u8fd0\u884c\uff0c\u4f60\u53ef\u4ee5\u53d1\u73b0\u8fd9\u53e5\u8bdd\u5e76\u4e0d\u603b\u662f\u7d27\u6328\u5728\u4e34\u754c\u533a\u4e4b\u540e\u5c31\u88ab\u6267\u884c\u7684\uff0c\u56e0\u4e3a\u51fa\u4e86\u4e34\u754c\u533a\uff0c\u8fd9\u51e0\u4e2a\u5b50\u8fdb\u7a0b\u5c31\u662f\u666e\u901a\u7684\u4ea4\u4e92\u8fd0\u884c\u800c\u5df2\u3002<\/p>\n<p>\u6240\u4ee5\uff0c\u867d\u7136\u8fd9\u5e76\u4e0d\u662f\u6211\u4eec\u4ee5\u524d\u719f\u6089\u7684\u90a3\u4e2a\u591a\u8fdb\u7a0b\u4e92\u65a5\u4f7f\u7528\u4e00\u4e2a\u4e34\u754c\u533a\u7684\u573a\u666f\uff0c\u4f46\u4e5f\u53ef\u4ee5\u4f53\u73b0\u8fdb\u7a0b\u5bf9\u4e34\u754c\u533a\u7684\u4e92\u65a5\u8bbf\u95ee\u3002\u8fd9\u6837\u8bf4\u6765\u53ef\u80fd\u4f1a\u6709\u70b9\u7ed5\uff0c\u4f46\u662f\u4ed4\u7ec6\u60f3\u60f3\u4e5f\u5e94\u8be5\u4f1a\u7406\u89e3\u3002<\/p>\n<p>\u90a3\u4e48\u5982\u4f55\u5b9e\u73b0\u591a\u4e2a\u8fdb\u7a0b\u4e92\u65a5\u8bbf\u95ee\u4e00\u4e2a\u4e34\u754c\u533a\uff1f\u4f60\u4e5f\u8bb8\u4f1a\u60f3\u5230vfork\u51fd\u6570\uff0c\u53ef\u662f\u6bd4\u8f83\u7cdf\u7cd5\u7684\u662fvfork\u540e\uff0c\u7236\u8fdb\u7a0b\u5728\u5b50\u8fdb\u7a0b\u9000\u51fa\u524d\u603b\u662f\u963b\u585e\uff0c\u8fd9\u6837\u5e76\u4e0d\u9002\u5408\u6211\u4eec\u8fd9\u91cc\u4f9d\u6b21\u751f\u6210\u591a\u4e2a\u5b50\u8fdb\u7a0b\u7684\u60c5\u51b5\u3002\u5982\u679c\u8fd8\u611f\u5230\u56f0\u60d1\uff0c\u90a3\u4e48\u4e5f\u6ca1\u5173\u7cfb\uff0c\u4e0d\u59a8\u5728\u5b66\u4e60\u4e86\u5171\u4eab\u5185\u5b58\u4e4b\u540e\uff0c\u518d\u6765\u7406\u89e3\u672c\u6587\u3002\u7528<strong>\u5171\u4eab\u5185\u5b58\u624d\u53ef\u4ee5\u5b9e\u73b0\u591a\u4e2a\u8fdb\u7a0b\u90fd\u8bbf\u95ee\u4e00\u4e2a\u5185\u5b58\u533a<\/strong>\u3002<\/p>\n<pre class=\"brush:c\">int main(int argc,char** argv)\r\n{\r\n\tint proj_id;\r\n\tint semid;\r\n\tunion semun arg;\r\n\tpid_t pid;\r\n\tkey_t key;\r\n\tint num;\r\n\tint i,j;\r\n\r\n\tif(argc!=2)\r\n\t{\r\n\t\tprintf(\"error:%s num\\n\",argv[0]);\r\n\t\treturn -1;\r\n\t}\r\n\r\n\tnum=atoi(argv[1]);\r\n\r\n\t\/\/create key\r\n\tproj_id=2;\r\n\tif((key=ftok(\".\",proj_id))==-1)\r\n\t{\r\n\t\tprintf(\"generating IPC key failed\\n\");\r\n\t\treturn -1;\r\n\t}\r\n\r\n\t\/\/create a semaphore set\r\n\tif((semid=semget(key,1,IPC_CREAT|0666))==-1)\r\n\t{\r\n\t\tprintf(\"creating semaphore set failed\\n\");\r\n\t\treturn -1;\r\n\t}\r\n\r\n\targ.val=1;\r\n\tif(semctl(semid,0,SETVAL,arg)==-1)\r\n\t{\r\n\t\tprintf(\"set semval failed\\n\");\r\n\t\treturn -1;\r\n\t}\r\n\r\n\tfor(i=0;i&lt;\\num;i++)\r\n\t{\r\n\t\tpid=fork();\r\n\t\tif(pid&lt;0)\r\n\t\t{\r\n\t\t\tprintf(\"creating new process failed\\n\");\r\n\t\t\treturn -1;\r\n\t\t}\r\n\t\telse if(pid==0)\r\n\t\t{\r\n\t\t\tif((semid=semget(key,1,0))==-1)\r\n\t\t\t{\r\n\t\t\t\tprintf(\"geting semid failed in the child process\\n\");\r\n\t\t\t\treturn -1;\r\n\t\t\t}\r\n\r\n\t\t\tp(semid,0);\r\n\t\t\tprintf(\"===process %d enter the critical section===\\n\",getpid());\r\n           \t\tsleep(1);\r\n\t\t\tprintf(\"===process:%d is accessing=================\\n\",getpid());\r\n\t\t\tsleep(1);\r\n\t\t\tprintf(\"===process %d leave the critical section===\\n\",getpid());\r\n\t\t\tsleep(1);\r\n\t\t\tv(semid,0);\r\n\r\n\t\t\treturn 0;\r\n\t\t}\r\n\t}\r\n\r\n\tfor(i=0;i&lt;\\num;i++)\r\n\t{\r\n\t\twait(NULL);\r\n\t}\r\n\r\n\tif(semctl(semid,0,IPC_RMID,0)==-1)\r\n\t{\r\n\t\tprintf(\"remove the sem set failed\\n\");\r\n\t\treturn -1;\r\n\t}\r\n\r\n\treturn 0;\r\n}<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>\u672c\u6587\u4e3a\u5927\u5bb6\u5448\u73b0\u7684\u4ee3\u7801\u53ef\u4ee5\u5b9e\u73b0\u8fdb\u7a0b\u7684\u4e92\u65a5\u3002\u4e0b\u9762\u4ee3\u7801\u7701\u53bb\u4e86pv\u64cd\u4f5c\u7684\u7684\u5177\u4f53\u5b9a\u4e49\u4ee5\u53caunion semun\u7684\u5b9a\u4e49\uff08\u53ef [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[140],"tags":[109,139,142,402],"class_list":["post-1213","post","type-post","status-publish","format-standard","hentry","category-140","tag-c","tag-ipc","tag-142","tag-402"],"views":6517,"_links":{"self":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/1213","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/comments?post=1213"}],"version-history":[{"count":0,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/posts\/1213\/revisions"}],"wp:attachment":[{"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/media?parent=1213"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/categories?post=1213"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/edsionte.com\/techblog\/wp-json\/wp\/v2\/tags?post=1213"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}