带有IMAP的PHP CLI，5秒启动延迟

在RedHat Enterprise 6.5服务器上安装了“php-imap-5.3.3-27.el6_5.x86_64”后，PHP的CLI版本总是需要5秒钟才能运行：

php -n -d extension=imap.so -v PHP 5.3.3 (cli) (built: Dec 5 2013 07:09:40) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies real 0m5.023s user 0m0.006s sys 0m0.010s 

请注意，“-n”禁用通常的php.ini，只加载“imap.so”（仅用于debugging目的）。

你有什么想法可能造成这种情况？ 它似乎是暂停的东西，可能是一个超时？

在SELinux审计日志中没有提到任何东西，但是有趣的是，加载这个库似乎正在尝试（失败？）连接到DNS服务器出于某种原因？

• 发件人地址被拒绝（未findmxlogging）
• 如何比较2个TCP / IP堆栈或实现？
• 域名在新旧主机服务之间来回切换
• 为什么在路线53 + S3组合中使用CNAME
• 什么是我的DNS中的.localdomain查询？

 strace -s -c php -n -d extension=imap.so -v execve("/usr/bin/php", [...], [/* 24 vars */]) = 0 brk(0) = 0x15e2000 [...] socket(PF_INET, SOCK_DGRAM|SOCK_NONBLOCK, IPPROTO_IP) = 3 connect(3, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.1.1")}, 16) = 0 poll([...], 1, 0) = 1 ([...]) sendto(3, ""..., 38, MSG_NOSIGNAL, NULL, 0) = 38 poll([...], 1, 5000) = 1 ([...]) sendto(3, ""..., 38, MSG_NOSIGNAL, NULL, 0) = 38 poll([...], 1, 4999) = 1 ([...]) ioctl(3, FIONREAD, [254]) = 0 recvfrom(3, ""..., 2048, 0, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.1.1")}, [16]) = 254 poll([...], 1, 4998 [... 5 second pause ...] ) = 0 (Timeout) poll([...], 1, 0) = 1 ([...]) sendto(3, ""..., 38, MSG_NOSIGNAL, NULL, 0) = 38 poll([...], 1, 5000) = 1 ([...]) ioctl(3, FIONREAD, [254]) = 0 recvfrom(3, ""..., 2048, 0, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.1.1")}, [16]) = 254 poll([...], 1, 4998) = 1 ([...]) sendto(3, ""..., 38, MSG_NOSIGNAL, NULL, 0) = 38 poll([...], 1, 4998) = 1 ([...]) ioctl(3, FIONREAD, [97]) = 0 recvfrom(3, ""..., 1794, 0, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.1.1")}, [16]) = 97 close(3) = 0 alarm(0) = 0 [...] 

经过检查，DNS似乎响应良好：

 dig +short example.com @192.168.1.1 93.184.216.119 

至于强制性计数输出：

 strace -c php -n -d extension=imap.so -v PHP 5.3.3 (cli) (built: Dec 5 2013 07:09:40) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------- 27.14 0.000019 0 103 mmap 25.71 0.000018 0 48 read 25.71 0.000018 5 4 socket 21.43 0.000015 0 47 fstat 0.00 0.000000 0 1 write 0.00 0.000000 0 49 2 open 0.00 0.000000 0 51 close 0.00 0.000000 0 6 2 stat 0.00 0.000000 0 8 poll 0.00 0.000000 0 1 lseek 0.00 0.000000 0 54 mprotect 0.00 0.000000 0 19 munmap 0.00 0.000000 0 14 brk 0.00 0.000000 0 4 rt_sigaction 0.00 0.000000 0 6 rt_sigprocmask 0.00 0.000000 0 12 ioctl 0.00 0.000000 0 4 3 access 0.00 0.000000 0 3 alarm 0.00 0.000000 0 3 2 connect 0.00 0.000000 0 5 sendto 0.00 0.000000 0 3 recvfrom 0.00 0.000000 0 3 recvmsg 0.00 0.000000 0 1 bind 0.00 0.000000 0 1 getsockname 0.00 0.000000 0 1 execve 0.00 0.000000 0 1 uname 0.00 0.000000 0 4 fcntl 0.00 0.000000 0 1 getcwd 0.00 0.000000 0 1 getrlimit 0.00 0.000000 0 1 statfs 0.00 0.000000 0 1 arch_prctl 0.00 0.000000 0 11 1 futex 0.00 0.000000 0 1 set_tid_address 0.00 0.000000 0 1 set_robust_list ------ ----------- ----------- --------- --------- ---------------- 100.00 0.000070 473 10 total 

和ltrace（有相当多的memcpy / free / memset时间）：

 ltrace -c php -n -d extension=imap.so -v PHP 5.3.3 (cli) (built: Dec 5 2013 07:09:40) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies % time seconds usecs/call calls function ------ ----------- ----------- --------- -------------------- 41.92 7.377898 790 9331 memcpy 32.32 5.689380 581 9788 free 11.48 2.021224 14972 135 memset 7.79 1.371877 147 9297 malloc 2.86 0.503343 157 3191 strlen 1.62 0.285582 147 1940 __ctype_tolower_loc 0.84 0.147136 145 1010 strrchr 0.37 0.065134 148 440 calloc 0.21 0.036233 151 239 realloc 0.14 0.024520 12260 2 getprotobyname 0.12 0.020486 20486 1 dlopen 0.07 0.012101 124 97 strcasecmp 0.07 0.011930 142 84 strtol 0.06 0.010258 170 60 strchr 0.02 0.004310 172 25 _setjmp 0.02 0.003569 148 24 __ctype_b_loc 0.02 0.002862 2862 1 ERR_load_crypto_strings 0.01 0.001339 148 9 0.01 0.001298 1298 1 using_history 0.01 0.001027 171 6 strncasecmp 0.01 0.000898 898 1 dlclose 0.01 0.000893 127 7 getenv 0.00 0.000682 170 4 fflush 0.00 0.000371 371 1 tzset 0.00 0.000358 179 2 xmlParserInputBufferCreateFilenameDefault 0.00 0.000354 354 1 ERR_load_ERR_strings 0.00 0.000351 351 1 setlocale 0.00 0.000346 173 2 xmlSetGenericErrorFunc 0.00 0.000341 170 2 xmlOutputBufferCreateFilenameDefault 0.00 0.000326 163 2 signal 0.00 0.000326 163 2 __strtok_r 0.00 0.000312 312 1 SSL_library_init 0.00 0.000303 303 1 OpenSSL_add_all_ciphers 0.00 0.000282 282 1 EVP_cleanup 0.00 0.000253 253 1 xmlInitParser 0.00 0.000245 245 1 OPENSSL_add_all_algorithms_noconf 0.00 0.000224 224 1 write 0.00 0.000223 223 1 sigprocmask 0.00 0.000191 191 1 OpenSSL_add_all_digests 0.00 0.000187 187 1 xmlCleanupParser 0.00 0.000178 178 1 xmlSetStructuredErrorFunc 0.00 0.000176 176 1 xmlRelaxNGCleanupTypes 0.00 0.000175 175 1 ERR_load_EVP_strings 0.00 0.000175 175 1 X509_get_default_cert_area 0.00 0.000172 172 1 sigemptyset 0.00 0.000171 171 1 xmlResetLastError 0.00 0.000170 170 1 strncmp 0.00 0.000169 169 1 time 0.00 0.000169 169 1 sigaddset 0.00 0.000167 167 1 SSL_get_ex_new_index 0.00 0.000154 154 1 __gmp_set_memory_functions 0.00 0.000153 153 1 pcre_version 0.00 0.000151 151 1 gnu_get_libc_version 0.00 0.000145 145 1 __xmlParserVersion 0.00 0.000092 92 1 getcwd 0.00 0.000079 79 1 dlsym 0.00 0.000072 72 1 __strdup ------ ----------- ----------- --------- -------------------- 100.00 17.601541 35732 total 

相关，但不解决：

 http://superuser.com/questions/336177/running-php-as-cli-takes-a-long-time http://trac.macports.org/ticket/35222 https://bugs.php.net/bug.php?id=41968 https://github.com/liip/php-osx/issues/102 

 tcpdump -vvv port 53 

 127.0.0.1 example.net 

 time php -n -d extension=imap.so -v PHP 5.3.3 (cli) (built: Dec 5 2013 07:09:40) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies real 0m0.011s user 0m0.007s sys 0m0.003s