{"id":612,"date":"2017-01-04T14:57:41","date_gmt":"2017-01-04T06:57:41","guid":{"rendered":"http:\/\/www.5x44.cn\/?p=612"},"modified":"2017-01-04T16:25:57","modified_gmt":"2017-01-04T08:25:57","slug":"sigcld%e8%af%ad%e4%b9%89","status":"publish","type":"post","link":"https:\/\/www.5x44.cn\/?p=612","title":{"rendered":"SIGCLD\u8bed\u4e49"},"content":{"rendered":"

SIGCLD<\/span>\u548cSIGCH<\/span>LD<\/span>\u8fd9\u4e24\u4e2a\u4fe1\u53f7\u4e00\u76f4\u90fd\u5f88\u5bb9\u6613\u6df7\u6dc6\u3002\u9996\u5148\uff0cSIGCLD<\/span>\uff08\u6ca1\u6709H\uff09\u662fSystem V\u7684\u540d\u5b57\uff0c\u800c\u4e14\u8fd9\u4e2a\u4fe1\u53f7\u5728BSD\u7cfb\u7edf\u4e2d\u6709\u4e0d\u540c\u7684\u8bed\u4e49\uff0c\u88ab\u547d\u540d\u4e3aSIGCH<\/span>LD<\/span>\u3002POSIX.1\u4fe1\u53f7\u540c\u6837\u547d\u540d\u4e3aSIGCH<\/span>LD<\/span>\u3002<\/p>\n

BSD\u4e2d\u7684SIGCH<\/span>LD<\/span>\u4fe1\u53f7\u7684\u8bed\u4e49\u662f\u6b63\u5e38\u7684\uff0c\u548c\u5176\u5b83\u4fe1\u53f7\u7684\u8bed\u4e49\u662f\u4e00\u6837\u7684\u3002\u5f53\u4fe1\u53f7\u53d1\u751f\u65f6\uff0c\u5b50\u8fdb\u7a0b\u7684\u72b6\u6001\u4f1a\u53d1\u751f\u6539\u53d8\uff0c\u5e76\u4e14\u6211\u4eec\u9700\u8981\u53bb\u8c03\u7528wait<\/span>\u67d0\u4e00\u7248\u672c\u4e2d\u7684\u4e00\u4e2a\uff0c\u53bb\u5224\u65ad\u53d1\u751f\u4e86\u4ec0\u4e48\u3002<\/p>\n

System V\u4e2d\uff0c\u65e0\u8bba\u53ef\u65f6\uff0cSIGCLD<\/span>\u4fe1\u53f7\u7684\u5904\u7406\u65b9\u5f0f\u90fd\u4e0d\u540c\u4e8e\u5176\u5b83\u4fe1\u53f7\u3002\u5982\u679c\u6211\u4eec\u4f7f\u7528signal<\/span>\u6216sigset<\/span>\uff08\u8fd9\u4e2a\u51fd\u6570\u662f\u7528\u4e8e\u517c\u5bb9\u66f4\u8001\u7684SVR3\u7cfb\u7edf\uff0c\u5728\u8be5\u7cfb\u7edf\u4e2d\u90e8\u7f72\u4fe1\u53f7\u7684\uff09\u90e8\u7f72\u8be5\u4fe1\u53f7\uff0c\u57faSVR4\u7684\u7cfb\u7edf\u5ef6\u7eed\u4e86\u8fd9\u4e2a\u6709\u95ee\u9898\u7684\u4f20\u7edf\uff08\u4e5f\u5c31\u662f\u517c\u5bb9\u6027\u9650\u5236\uff09\u3002SIGCLD<\/span>\u7684\u5904\u7406\u65b9\u5f0f\u7531\u4ee5\u4e0b\u7ec4\u6210\uff1a<\/p>\n

    \n
  1. \u5982\u679c\u8fdb\u7a0b\u7279\u522b\u6307\u5b9a\u8be5\u4fe1\u53f7\u90e8\u7f72\u5230SIG_IGN<\/span>\uff0c\u8be5\u8fdb\u7a0b\u7684\u5b50\u8fdb\u7a0b\u5c06\u4e0d\u4f1a\u4ea7\u751f\u50f5\u5c38\u8fdb\u7a0b\u3002\u6ce8\u610f\uff1a\u8fd9\u4e0d\u540c\u4e8e\u5b83\u7684\u9ed8\u8ba4\u52a8\u4f5c\uff08SIG_DFL<\/span>\uff09\uff0c\u9ed8\u8ba4\u4e3a\u5ffd\u7565\u3002\u53d6\u800c\u4ee3\u4e4b\u5728\u7ec8\u6b62\u65f6\u4f1a\u4e22\u5f03\u5b50\u8fdb\u7a0b\u7684\u72b6\u6001\u3002\u5982\u679c\u5b83\u8fde\u7eed\u7684\u8c03\u7528wait<\/span>\u51fd\u6570\uff08\u51e0\u4e2a\u7248\u672c\u4e2d\u7684\u4e00\u4e2a\uff09\uff0c\u8c03\u7528\u7684\u8fdb\u7a0b\u4f1a\u963b\u585e\u7a0b\u5e8f\uff0c\u76f4\u5230\u6240\u6709\u5b83\u7684\u5b50\u8fdb\u7a0b\u7ec8\u6b62\uff0c\u5e76\u4e14wait<\/span>\u8fd4\u56de1\u7684\u540c\u65f6\u628aerrno<\/span>\u8bbe\u7f6e\u6210ECHILD<\/span>\u3002\uff08\u8be5\u4fe1\u53f7\u7684\u9ed8\u8ba4\u52a8\u4f5c\u662f\u5ffd\u7565\uff0c\u4f46\u662f\u8fd9\u4e2a\u9ed8\u8ba4\u52a8\u4f5c\u4e0d\u4f1a\u6709\u9884\u8ba1\u7684\u6548\u679c\u53d1\u751f\u3002\u53d6\u5c14\u4ee3\u4e4b\uff0c\u6211\u4eec\u5fc5\u987b\u624b\u52a8\u6307\u5b9a\u5b83\u7684\u52a8\u4f5c\u4e3aSIG_IGN<\/span>\u3002\uff09
    \nPOSIX.1\u6ca1\u6709\u6307\u5b9a\u5f53SIGCHLD<\/span>\u88ab\u5ffd\u7565\u540e\u4f1a\u53d1\u751f\u4ec0\u4e48\uff0c\u6240\u4ee5\u8fd9\u4e2a\u884c\u4e3a\u662f\u5141\u8bb8\u7684\u3002<\/em>
    \n BSD4.4\u4e2d\uff0c\u5982\u679cSIGCHLD<\/span>\u88ab\u5ffd\u7565\u540e\u4f1a\u4ea7\u751f\u50f5\u5c38\u8fdb\u7a0b\u3002\u5982\u679c\u60f3\u907f\u514d\u50f5\u5c38\u8fdb\u7a0b\uff0c\u5fc5\u987b\u5bf9\u5b50\u8fdb\u7a0b\u4f7f\u7528wait<\/span>\u51fd\u6570\u3002FreeBSD 5.2.1\u5de5\u4f5c\u65b9\u5f0f\u548cBSD4.4\u7c7b\u4f3c\u3002Mac OS X 10.3\uff0c\u5f53SIGCHLD<\/span>\u88ab\u5ffd\u7565\u65f6\uff0c\u65e0\u8bba\u600e\u6837\u90fd\u4e0d\u4f1a\u5efa\u7acb\u50f5\u5c38\u8fdb\u7a0b\u3002<\/em>
    \n SVR4\u4e2d\uff0c\u5982\u679csignal<\/span>\u6216sigset<\/span>\u88ab\u8c03\u7528\uff0c\u8bbe\u7f6eSIGCHLD<\/span>\u7684\u9ed8\u8ba4\u52a8\u4f5c\u662f\u5ffd\u7565\uff0c\u50f5\u5c38\u8fdb\u7a0b\u662f\u7edd\u5bf9\u4e0d\u4f1a\u4ea7\u751f\u7684\u3002Solaris 9\u3001Linux 2.4.22\u548cSVR4\u7684\u884c\u4e3a\u662f\u4e00\u6837\u7684\u3002<\/em>
    \n \u5bf9\u4e8esigaction<\/span>\uff0c\u6211\u4eec\u80fd\u8bbe\u7f6eSA_NOCLDWAIT<\/span>\u6807\u8bb0\u53bb\u907f\u514d\u50f5\u5c38\u8fdb\u7a0b\u3002\u8fd9\u4e2a\u52a8\u4f5c\u652f\u6301\uff1aFreeBSD5.2.1, Linux 2.4.22, Mac OS X 10.3\u548cSolaris 9\u3002<\/em><\/li>\n
  2. \u5982\u679c\u6211\u4eec\u8bbe\u7f6eSIGCLD<\/span>\u7684\u884c\u4e3a\u662f\u201c\u6355\u83b7\u201d\uff0c\u5185\u6838\u4f1a\u7acb\u5373\u68c0\u67e5\u6240\u6709\u5b50\u8fdb\u7a0b\u662f\u5426\u5df2\u7ecf\u51c6\u5907\u597dwait<\/span>\u4e86\uff0c\u5982\u679c\u662f\u8fd9\u6837\uff0c\u8c03\u7528SIGCLD<\/span>\u5904\u7406\u51fd\u6570\u3002<\/li>\n<\/ol>\n

    \u7b2c\u4e8c\u9879\u6539\u53d8\u4e86\u4fe1\u53f7\u7684\u52a8\u4f5c\uff0c\u6211\u4eec\u8981\u4e3a\u4fe1\u53f7\u5199\u4e00\u4e2a\u5904\u7406\u52a8\u4f5c\u3002\u4e0b\u9762\u7528\u4e00\u4e2a\u4f8b\u5b50\u6765\u89e3\u91ca\u3002<\/p>\n

    \u4f8b\u5b50\uff1a<\/h2>\n\n\n\n
    \n
    Figure 10.6. System V SIGCLD<\/tt> handler that doesn’t work<\/span><\/h5>\n
    #include      \"apue.h\"\r\n#include      <sys\/wait.h>\r\n\r\nstatic void sig_cld(int);\r\n\r\nint\r\nmain()\r\n{\r\n    pid_t   pid;\r\n\r\n    if (signal(SIGCLD, sig_cld) == SIG_ERR)\r\n        perror(\"signal error\");\r\n    if ((pid = fork()) < 0) {\r\n        perror(\"fork error\");\r\n    } else if (pid == 0) {      \/* child *\/\r\n        sleep(2);\r\n        _exit(0);\r\n    }\r\n    pause();    \/* parent *\/\r\n    exit(0);\r\n}\r\n\r\nstatic void\r\nsig_cld(int signo)   \/* interrupts pause() *\/\r\n{\r\n    pid_t   pid;\r\n    int     status;\r\n\r\n    printf(\"SIGCLD received\\n\");\r\n    if (signal(SIGCLD, sig_cld) == SIG_ERR) \/* reestablish handler *\/\r\n        perror(\"signal error\");\r\n    if ((pid = wait(&status)) < 0)      \/* fetch child status *\/\r\n        perror(\"wait error\");\r\n    printf(\"pid = %d\\n\", pid);\r\n}\r\n<\/span><\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    \u4fe1\u53f7\u5904\u7406\u51fd\u6570\u505a\u7684\u7b2c\u4e00\u4ef6\u4e8b\u662f\u518d\u6b21\u8c03\u7528signal<\/span>\u51fd\u6570\uff0c\u53bb\u91cd\u65b0\u8fde\u63a5\u4fe1\u53f7\u5904\u7406\u51fd\u6570\uff08\u8fd9\u4e2a\u52a8\u4f5c\u662f\u5f53\u4fe1\u53f7\u88ab\u91cd\u7f6e\u4e3a\u5b83\u7684\u9ed8\u8ba4\u52a8\u4f5c\u5e76\u4e22\u5931\u65f6\uff0c\u6700\u5c0f\u5316\u65f6\u95f4\u7a97\u53e3”this action was to minimize the window of time when the signal is reset back to its default and could get lost.”\uff09\u3002\u8fd9\u663e\u793a\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\u3002\u8fd9\u4e2a\u4f8b\u5b50\u4e0d\u80fd\u5728\u4e00\u4e9b\u5e73\u53f0\u8fd0\u884c\u3002\u5982\u679c\u6211\u4eec\u7f16\u8bd1\u5e76\u8fd0\u884c\u5b83\u5728\u4e00\u4e9b\u4f20\u7edf\u7684System V\u5e73\u53f0\u4e0a\uff08\u5982\uff1aOpenServer 5\u6216UnixWare 7\uff09\uff0c\u8f93\u51fa\u5c06\u4f1a\u662f\u4e00\u4e9b\u8fde\u7eed\u7684SIGCLD received<\/span>\u884c\u3002\u6700\u7ec8\uff0c\u8fdb\u7a0b\u8fd0\u884c\u8d85\u51fa\u6808\u7a7a\u95f4\u5e76\u5f02\u5e38\u7ec8\u6b62\u3002<\/p>\n
    FreeBSD 5.2.1<\/strong>\u548cMac OS X 10.3<\/strong>\u5e76\u6ca1\u6709\u663e\u793a\u51fa\u8fd9\u4e2a\u95ee\u9898\uff0c\u56e0\u4e3a\u57fa\u4e8eBSD\u7684\u7cfb\u7edf\u901a\u5e38\u4e0d\u652f\u6301\u5386\u53f2\u4e0a\u7684System V\u4e2d\u7684SIGCLD<\/span>\u8bed\u6cd5\u3002Linux 2.4.22<\/strong>\u540c\u6837\u6ca1\u6709\u663e\u793a\u8fd9\u4e2a\u95ee\u9898\uff0c\u56e0\u4e3a\u5f53\u4e00\u4e2a\u8fdb\u7a0b\u51c6\u5907\u53bb\u6355\u83b7SIGCHLD<\/span>\u5e76\u4e14\u5b50\u8fdb\u7a0b\u5df2\u7ecf\u51c6\u5907\u597dwait<\/span>\u65f6\uff0c\u5b83\u5e76\u4e0d\u8c03\u7528SIGCHLD<\/span>\u4fe1\u53f7\u5904\u7406\u51fd\u6570\uff0c\u5373\u4fbfSIGCLD<\/span>\u548cSIGCHLD<\/span>\u5b9a\u4e49\u4e86\u76f8\u540c\u7684\u503c\u3002Solaris 9<\/strong>\uff0c\u867d\u7136\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\u4f1a\u8c03\u7528\u7528\u4fe1\u53f7\u5904\u7406\u51fd\u6570\uff0c\u4f46\u662f\u5b83\u5728\u5185\u6838\u4e2d\u5305\u542b\u4e86\u989d\u5916\u7684\u4ee3\u7801\u53bb\u907f\u514d\u8fd9\u4e2a\u95ee\u9898\u3002<\/em><\/p>\n
    \u867d\u7136APUE\u4e2d\u63cf\u8ff0\u7684\u56db\u79cd\u5e73\u53f0\u90fd\u89e3\u51b3\u4e86\u8fd9\u4e2a\u95ee\u9898\uff0c\u4f46\u5b9e\u9645\u5e73\u53f0\u4e0a\u8fd9\u4e2a\u95ee\u9898\u8fd8\u662f\u5b58\u5728\uff0c\u53ea\u662f\u6ca1\u6709\u88ab\u5b9a\u4f4d\u5230\u3002<\/em><\/p>\n
    \u8fd9\u4e2a\u793a\u4f8b\u7a0b\u5e8f\u7684\u95ee\u9898\u662f\uff1a\u5728\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u7684\u5f00\u59cb\u4f4d\u7f6e\u8c03\u7528signal<\/span>\uff0c\u4e5f\u5c31\u662f\u5f15\u7528\u4e4b\u524d\u8ba8\u8bba\u7684\u7b2c2\u9879\u2014\u2014\u5185\u6838\u68c0\u67e5\u5b50\u8fdb\u7a0b\u662f\u5426\u987b\u8981wait<\/span>\uff0c\u6240\u4ee5\u5b83\u4f1a\u4ea7\u751f\u65b0\u7684\u8c03\u7528\u5230\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u3002\u8fd9\u4e2a\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u8c03\u7528\u4e86signal<\/span>\uff0c\u5e76\u4e14\u6240\u6709\u7684\u8fc7\u7a0b\u8981\u91cd\u6765\u4e00\u6b21\u3002<\/p>\n
    \u4e3a\u4e86\u4fee\u590d\u8fd9\u4e2a\u95ee\u9898\uff0c\u6211\u4eec\u5fc5\u987b\u79fb\u52a8signal<\/span>\u51fd\u6570\u5230wait<\/span>\u8c03\u7528\u4e4b\u540e\u3002\u901a\u8fc7\u8fd9\u4e48\u505a\uff0c\u6211\u4eec\u5728\u5f97\u5230\u5b50\u8fdb\u7a0b\u7ec8\u6b62\u72b6\u6001\u540e\u8c03\u7528signal<\/span>\uff1b\u53ea\u6709\u5f53\u4e00\u4e9b\u5b50\u8fdb\u7a0b\u521a\u597d\u7ed3\u675f\uff0c\u5185\u6838\u624d\u518d\u6b21\u4ea7\u751f\u4fe1\u53f7\u3002<\/p>\n
    POSIX.1\u58f0\u660e\uff0c\u5f53\u6211\u4eec\u4e3aSIGCHLD<\/span>\u5efa\u7acb\u4fe1\u53f7\u5904\u7406\u51fd\u6570\uff0c\u5e76\u4e14\u5b58\u5728\u4e00\u4e2a\u7ec8\u6b62\u7684\u5b50\u8fdb\u7a0b\u6211\u4eec\u8fd8\u6ca1\u6709wait<\/span>\u65f6\uff0c\u5e76\u672a\u8be6\u7ec6\u6307\u51fa\u4fe1\u53f7\u662f\u5426\u5df2\u7ecf\u4ea7\u751f\u3002\u8fd9\u5141\u8bb8\u4e4b\u524d\u63cf\u8ff0\u7684\u884c\u4e3a\u3002\u4f46\u662f\u56e0\u4e3aPOSIX.1\u5728\u4fe1\u53f7\u53d1\u751f\u65f6\uff0c\u5e76\u4e0d\u4f1a\u91cd\u7f6e\u4fe1\u53f7\u7684\u9ed8\u8ba4\u52a8\u4f5c\uff0c\u6240\u4ee5\u5e76\u4e0d\u987b\u8981\u6211\u4eec\u603b\u662f\u5728\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u4e2d\u4e3aSIGCHLD<\/span>\u5efa\u7acb\u4fe1\u53f7\u5904\u7406\u51fd\u6570\u3002<\/em><\/p>\n
    \u53bb\u719f\u6089\u4f60\u6240\u4f7f\u7528\u5b9e\u73b0\u7684SIGCHLD<\/span>\u8bed\u4e49\u3002\u7279\u522b\u662f\u4f60\u8981\u77e5\u9053\u4e00\u4e9b\u7cfb\u7edf\u662f\u901a\u8fc7#define SIGCHLD<\/span>\u6765\u5b9a\u4e49SIGCLD<\/span>\u7684\uff0c\u53cd\u4e4b\u4ea6\u7136\u3002\u53ef\u4ee5\u901a\u8fc7\u6539\u540d\u7684\u65b9\u5f0f\u8ba9\u4f60\u7684\u7a0b\u5e8f\u5728\u5176\u5b83\u7cfb\u7edf\u4e0a\u7f16\u8bd1\uff0c\u4f46\u662f\u5982\u679c\u90a3\u4e2a\u7cfb\u7edf\u662f\u4f9d\u8d56\u4e8e\u53e6\u4e00\u79cd\u8bed\u4e49\u7684\u8bdd\uff0c\u90a3\u53ef\u80fd\u4e0d\u80fd\u5de5\u4f5c\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
    SIGCLD\u548cSIGCHLD\u8fd9\u4e24\u4e2a\u4fe1\u53f7\u4e00\u76f4\u90fd\u5f88\u5bb9\u6613\u6df7\u6dc6\u3002\u9996\u5148\uff0cSIGCLD\uff08\u6ca1\u6709H\uff09\u662fSystem V\u7684\u540d\u5b57\uff0c\u800c\u4e14\u8fd9\u4e2a\u4fe1\u53f7\u5728BSD\u7cfb\u7edf\u4e2d\u6709\u4e0d\u540c\u7684\u8bed\u4e49\uff0c\u88ab\u547d\u540d\u4e3aS…<\/p>\n
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