Re: Apache Error of $r->read failed to read

[Stas Bekman]

[bouncing back to the list with additional info]

Chris Faust wrote:
Ouch, in other words its going to be a tough on to track down :)..

Thanks Stas, I at least have some direction now.
what you could do is to go to the httpd source and change it to log the error. 
Look in modules/http/http_protocol.c:1884

    /* We lose the failure code here.  This is why ap_get_client_block should
     * not be used.
     */
    if (rv != APR_SUCCESS) {
        /* if we actually fail here, we want to just return and
         * stop trying to read data from the client.
         */
        r->connection->keepalive = AP_CONN_CLOSE;
        apr_brigade_destroy(bb);
        return -1;
    }
So log it there:

    if (rv != APR_SUCCESS) {
      ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, "read failed");
        /* if we actually fail here, we want to just return and
         * stop trying to read data from the client.
         */
        r->connection->keepalive = AP_CONN_CLOSE;
        apr_brigade_destroy(bb);
        return -1;
    }


-Chris

----- Original Message ----- 
From: "Stas Bekman" <[EMAIL PROTECTED]>
To: "Chris Faust" <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Wednesday, May 28, 2003 8:15 PM
Subject: Re: Apache Error of $r->read failed to read



Chris Faust wrote:

Hi,

We have been having some problems where all of a sudden apache will
start logging the error of:
[error] mod_perl: $r->read failed to read

Multiple times (100s in less then 10th of a sec), often it will get to
the point where load on the machine goes through the roof and apache has
problems responding and it appears to be the number of requests that are
happening as limits that shouldn't be reached like DB connections and
apache processes are maxing out during non-peak hours.
From what we could see it looked like someone outside was sending all
kind of linefeeds and whatnot within the URL which was documented in the
Apache 45 release which we did update - now we are down to getting the
above mod_perl error and shortly after that starts all hell breaks

loose.

Nowhere in our code do we directly call the "read" method nor can I find
anything relating to the error so I'm a little lost on what I can do.
Any ideas?
You probably use CGI.pm or something else that calls $r->read(). This
happends

in xs/Apache/RequestIO/Apache__RequestIO.h (hint grep the mod_perl source
code):

                /*
                 * XXX: as stated in ap_get_client_block, the real
                 * error gets lots, so we only know that there was one
                 */
                ap_log_error(APLOG_MARK, APLOG_ERR, 0, r->server,
                         "mod_perl: $r->read failed to read");
                break;
As you can see from the comment due to a bad implementation of
ap_get_client_block in Apache, the error is not available. I'm planning to
rewrite all these functions to get rid of ap_get_client_block, and work
with

bucket brigades instead.

In any case that won't solve the problem that you are seeing, I'd dig in
Apache. e.g. trying to use mod_cgi (which doesn't use ap_get_client_block)
to

reproduce the problem and ask at the httpd list.

__________________________________________________________________
Stas Bekman            JAm_pH ------> Just Another mod_perl Hacker
http://stason.org/     mod_perl Guide ---> http://perl.apache.org
mailto:[EMAIL PROTECTED] http://use.perl.org http://apacheweek.com
http://modperlbook.org http://apache.org   http://ticketmaster.com




--

__________________________________________________________________
Stas Bekman            JAm_pH ------> Just Another mod_perl Hacker
http://stason.org/     mod_perl Guide ---> http://perl.apache.org
mailto:[EMAIL PROTECTED] http://use.perl.org http://apacheweek.com
http://modperlbook.org http://apache.org   http://ticketmaster.com