附录:对某次跟踪状况的详细分析
本附录描述了运行在Linux上的Apache 1.3系统调用的跟踪情况。运行时(run-time)配置文件中除了必要的缺省选项外还增加了:
AllowOverride none Options FollowSymLinks
被请求的文件是一个6K的静态网页,其中不包含特殊内容。对于非静态或者伴随有内容协商的请求,跟踪结果将有明显的不同(一些情况下会十分晦涩)。我们将首先列出完整的跟踪结果,然后逐条进行分析。(它是由strace跟踪程序生成的,其他类似的程序包括truss、ktrace和par)
accept(15, {sin_family=AF_INET, sin_port=htons(22283), sin_addr=inet_addr("127.0.0.1")}, [16]) = 3 flock(18, LOCK_UN) = 0 sigaction(SIGUSR1, {SIG_IGN}, {0x8059954, [], SA_INTERRUPT}) = 0 getsockname(3, {sin_family=AF_INET, sin_port=htons(8080), sin_addr=inet_addr("127.0.0.1")}, [16]) = 0 setsockopt(3, IPPROTO_TCP1, [1], 4) = 0 read(3, "GET /6k HTTP/1.0\r\nUser-Agent: "..., 4096) = 60 sigaction(SIGUSR1, {SIG_IGN}, {SIG_IGN}) = 0 time(NULL) = 873959960 gettimeofday({873959960, 404935}, NULL) = 0 stat("/home/dgaudet/ap/apachen/htdocs/6k", {st_mode=S_IFREG|0644, st_size=6144, ...}) = 0 open("/home/dgaudet/ap/apachen/htdocs/6k", O_RDONLY) = 4 mmap(0, 6144, PROT_READ, MAP_PRIVATE, 4, 0) = 0x400ee000 writev(3, [{"HTTP/1.1 200 OK\r\nDate: Thu, 11"..., 245}, {"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 6144}], 2) = 6389 close(4) = 0 time(NULL) = 873959960 write(17, "127.0.0.1 - - [10/Sep/1997:23:39"..., 71) = 71 gettimeofday({873959960, 417742}, NULL) = 0 times({tms_utime=5, tms_stime=0, tms_cutime=0, tms_cstime=0}) = 446747 shutdown(3, 1 /* send */) = 0 oldselect(4, [3], NULL, [3], {2, 0}) = 1 (in [3], left {2, 0}) read(3, "", 2048) = 0 close(3) = 0 sigaction(SIGUSR1, {0x8059954, [], SA_INTERRUPT}, {SIG_IGN}) = 0 munmap(0x400ee000, 6144) = 0 flock(18, LOCK_EX) = 0
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