mod_jk 1.2.20 max_packet_size handling

[Peter Rossbach]

Hi Rainer and Mladen,

I made the paketSize port to tomcat 5.5 tree. Now, I start some  
testing and ...

- I have successfull send more than 8k to the client with a download  
request.
But I must patch o.a.c.connector.Response and  
AjpAprProcessor.SocketOutputBuffer
and JkInputStream to set correct outputbuffer size. Currenty I'm not  
port this back to tomcat 6.0.x!

- second use case: Test a post file upload
mod_jk don't send more then 8k at a fileupload request!

use case: - ( Sorry for the long description)

Send a http POST file upload

--
Request:

POST /fileupload/fileuploaddemo.jsp HTTP/1.1
Accept: */*
Accept-Language: de-de
Accept-Encoding: gzip, deflate
Cookie: JSESSIONID=246F48F8E1C82B3EB7B800EEDA3256BB.node01
Referer: http://127.0.0.1:2090/fileupload/fileuploaddemo.htm
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; de-de)  
AppleWebKit/418.9.1 (KHTML, like Gecko) Safari/419.3
Content-Length: 16832
Content-Type: multipart/form-data; boundary=----------0xKhTmLbOuNdArY
Connection: keep-alive
Host: 127.0.0.1:2090

------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="name"

16k.bin-5
------------0xKhTmLbOuNdArY
Content-Disposition: form-data; name="myimage"; filename="16k-5.bin"
Content-Type: application/macbinary

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== SNIP ==


== mod_jk log analyse: ===

a)Apache  -> JK_AJP13_FORWARD_REQUEST -> Tomcat )
jk_ajp_common.c (893): sending to ajp13 pos=4 len=450 max=16384
[Tue Dec 12 13:09:57 2006] [5167:0000] [debug]  
ajp_connection_tcp_send_message::
jk_ajp_common.c (893): 0000    12 34 01 BE 02 04 00 08 48 54 54 50 2F  
31 2E 31
- .4......HTTP/1.1
[Tue Dec 12 13:09:57 2006] [5167:0000] [debug]  
ajp_connection_tcp_send_message::

b) only 8k are sent (Apache  -> DATA -> Tomcat )
[Tue Dec 12 13:09:57 2006] [5167:0000] [debug]  
ajp_send_request::jk_ajp_common.c
(1273): request body to send 16832 - request body to resend 0
[Tue Dec 12 13:09:57 2006] [5167:0000] [trace]  
ajp_read_into_msg_buff::jk_ajp_co
mmon.c (1098): enter
[Tue Dec 12 13:09:57 2006] [5167:0000] [trace]  
ajp_read_fully_from_server::jk_aj
p_common.c (1052): enter
[Tue Dec 12 13:09:57 2006] [5167:0000] [trace]  
ajp_read_into_msg_buff::jk_ajp_co
mmon.c (1135): exit
[Tue Dec 12 13:09:57 2006] [5167:0000] [trace]  
ajp_connection_tcp_send_message::
jk_ajp_common.c (889): enter
[Tue Dec 12 13:09:57 2006] [5167:0000] [debug]  
ajp_connection_tcp_send_message::
jk_ajp_common.c (893): sending to ajp13 pos=4 len=8192 max=16384
[Tue Dec 12 13:09:57 2006] [5167:0000] [debug]  
ajp_connection_tcp_send_message::
jk_ajp_common.c (893): 0000    12 34 1F FC 1F FA 2D 2D 2D 2D 2D 2D 2D  
2D 2D 2D
- .4....----------

== max is 16 k ==

c) Tomcat answer please send more packet size max 16k (Apache  <-  
JK_AJP13_GET_BODY_CHUNK <- Tomcat )
Tue Dec 12 13:09:57 2006] [5167:0000] [debug]  
ajp_connection_tcp_get_message::j
k_ajp_common.c (1029): received from ajp13 pos=0 len=3 max=16384
[Tue Dec 12 13:09:57 2006] [5167:0000] [debug]  
ajp_connection_tcp_get_message::j
k_ajp_common.c (1029): 0000    06 3F FA 00 00 00 00 00 00 00 00 00 00  
00 00 00
- .?..............
[Tue Dec 12 13:09:57 2006] [5167:0000] [trace]  
ajp_connection_tcp_get_message::j
k_ajp_common.c (1035): exit

d) but only 8k are sent again (Apache  -> DATA -> Tomcat )
...
k_ajp_common.c (1029): received from ajp13 pos=0 len=3 max=16384

[Tue Dec 12 13:09:57 2006] [5167:0000] [trace]  
ajp_process_callback::jk_ajp_comm
on.c (1461): exit
[Tue Dec 12 13:09:57 2006] [5167:0000] [trace]  
ajp_connection_tcp_send_message::
jk_ajp_common.c (889): enter
[Tue Dec 12 13:09:57 2006] [5167:0000] [debug]  
ajp_connection_tcp_send_message::
jk_ajp_common.c (893): sending to ajp13 pos=4 len=8192 max=16384
[Tue Dec 12 13:09:57 2006] [5167:0000] [debug]  
ajp_connection_tcp_send_message::
jk_ajp_common.c (893): 0000    12 34 1F FC 1F FA FB F7 CE A6 2F AC 2B  
FF 23 42
- .4......../.+.#B

e) Tomcat answer, please send more with packet size 16k (Apache  <-  
JK_AJP13_GET_BODY_CHUNK <- Tomcat )
...
f) rest are send (Apache  -> DATA -> Tomcat )
...
g) tomcat response header and body are send
...
h) Tomcat send end response

OK, but why mod_jk don't use configured max packet size?

===

==== mod_jk 1.2.20 config

<IfModule !mod_jk.c>
  LoadModule jk_module "modules/mod_jk.so"
</IfModule>
JkShmFile "logs/mod_jk.shm"

JkLogFile "logs/mod_jk.log"
JkLogLevel trace

JKWorkerProperty worker.list=loadbalancer,jkstatus
JKWorkerProperty worker.node01.port=7309
JKWorkerProperty worker.node01.host=localhost
JKWorkerProperty worker.node01.type=ajp13
JKWorkerProperty worker.node01.max_packet_size=16384
JKWorkerProperty worker.loadbalancer.balance_workers=node01
JKWorkerProperty worker.loadbalancer.type=lb
JKWorkerProperty worker.jkstatus.type=status
JkMount /jkstatus jkstatus
JkMount /last* loadbalancer
JkMount /fileupload* loadbalancer

====

search at mod_jk source and found following hardcoded size cutter:
====

jk_ajp_common.c

L1444:
 case JK_AJP13_GET_BODY_CHUNK:
        {
            int len = (int)jk_b_get_int(msg);

            if (len < 0) {
                len = 0;
            }
            if (len > AJP13_MAX_SEND_BODY_SZ) {
                len = AJP13_MAX_SEND_BODY_SZ;

The size at tomcat SEND_BODY message are cut to default and not to  
worker max_paket_size

Why the first send body not use the worker max_packet_size:

L1341 ??
       if (ae->left_bytes_to_send > 0) {
            int len = ae->left_bytes_to_send;
            if (len > AJP13_MAX_SEND_BODY_SZ) {
                len = AJP13_MAX_SEND_BODY_SZ;

Other fix length setting found at  L1101
   read_buf += AJP_HEADER_LEN; /* leave some space for the buffer  
headers */
    read_buf += AJP_HEADER_SZ_LEN;      /* leave some space for the  
read length */

    /* Pick the max size since we don't know the content_length */
    if (r->is_chunked && len == 0) {
        len = AJP13_MAX_SEND_BODY_SZ;
    }

Wrong or right?

Regards
Peter