Understanding the strace output

[Jon Ryder]

Hi everyone,

I am attempting to debug a problem I am having with
Apache, then it executes scripts though SSI.  With no
clues given in the apache error log, I took to using
stace.  Using the pid of child process which my
request is being served by, I attached stace, with the
-f option so it follows all forked() processes which I
thought may be needed, as the problem may be outside
of apache.

22383 read(7, "select name=\"1047383276\"><option"...,
8192) = 4096
22383 writev(3, [{"1000\r\n", 6}, {"select
name=\"1047383276\"><option"..., 4096}, {"\r\n", 2}],
3) = 4104
22383 read(7, 0xbffef860, 8192)         = -1 EAGAIN
(Resource temporarily unavailable)
22383 select(8, [7], NULL, NULL, NULL <unfinished ...>
10231 write(1, " width=\"209\" align=\"center\"
bgco"..., 4096) = 4096
22383 <... select resumed> )            = 1 (in [7])
22383 read(7, " width=\"209\" align=\"center\"
bgco"..., 8192) = 4096
22383 writev(3, [{"1000\r\n", 6}, {" width=\"209\"
align=\"center\" bgco"..., 4096}, {"\r\n", 2}], 3) =
4104
22383 read(7, 0xbffef860, 8192)         = -1 EAGAIN
(Resource temporarily unavailable)
22383 select(8, [7], NULL, NULL, NULL <unfinished ...>
10231 write(1, " Offers</a></strong></font></td>"...,
4096) = 4096
22383 <... select resumed> )            = 1 (in [7])
22383 read(7, " Offers</a></strong></font></td>"...,
8192) = 4096
22383 writev(3, [{"1000\r\n", 6}, {"
Offers</a></strong></font></td>"..., 4096}, {"\r\n",
2}], 3 <unfinished ...>
10231 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 fcntl64(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
10231 read(3, 0x8203ab8, 8192)          = -1 EAGAIN
(Resource temporarily unavailable)
10231 fcntl64(3, F_SETFL, O_RDWR)       = 0
10231 write(3, "\1\0\0\0\1", 5)         = 5
10231 shutdown(3, 2 /* send and receive */) = 0
10231 close(3)                          = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
10231 write(1, "ca,sans-serif\" size=\"2\"
color=\"#"..., 1190) = 1190
10231 munmap(0x40018000, 4096)          = 0
10231 _exit(0)                          = ?
22383 <... writev resumed> )            = 2230
22383 --- SIGCHLD (Child exited) ---

I am most interested in the reason why the EAGAIN
errors happen, as I believe that is the problem I am
having.  Anything I can do to trace what is causing
them?

I am using Linux 2.4.xx (RedHat).

Thanks in advance, and apologises if this is the wrong
place to ask,

Jon,


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