Aaron Bannert wrote: >On Thu, Jan 03, 2002 at 11:56:26AM -0500, Greg Ames wrote: > >>I do see some weirdness in 2.0.30 with www.apache.org/dyn/closer.cgi - >>it looks like we're doing one byte reads from the pipe to the cgi. I >>don't know yet if 2_0_28 does the same. That's all I've spotted so far, >>except for a couple of annoying extra syscalls that also exist in >>2_0_28. >> > >I don't think that would spike the run queue more than 1, no? > >Of course, one-byte reads from a cgi pipe are just plain bogus >to begin with, but on a different scale methinks. >
The one-byte reads are for the CGI's response header. The problem is that mod_cgi hands off the pipe (non-buffered) to ap_scan_script_header_err(), which does single-byte reads until it finds the end of the header. After that, mod_cgi finally builds a pipe-bucket, which is buffered, so the reading of the content happens in much larger chunks. The easiest solution I can think of is to change ap_scan_script_header_err() to accept a brigade rather than an apr_file_t, so that we can take advantage of the pipe bucket's buffering when reading the headers. Brian
