Re: HTTPS connections lock-up with 2.4.18

Joachim Achtzehnter Thu, 04 Feb 2016 00:17:43 -0800

Here is the backtrace:

#0  0xb7fddc40 in __kernel_vsyscall ()
#1  0xb7e05f03 in __read_nocancel () at ../sysdeps/unix/syscall-template.S:81
#2  0xb7f39589 in apr_socket_recv (sock=sock@entry=0x8156d18,
    buf=buf@entry=0x8168750 "html, body {\n   font-family: arial, helvetica, 
sans-serif;\n   font-size: 12px;\n   height: 100%;\n   margin:0;\n   padding:0;\n   
height:100%;\n}\nbody a, a:hover {\n   text-decoration: underline;\n   border:"..., 
len=len@entry=0xbffff5e4) at network_io/unix/sendrecv.c:81
#3  0xb7f744d5 in socket_bucket_read (a=0x8160fc8, str=0xbffff5e0,
    len=0xbffff5e4, block=APR_NONBLOCK_READ)
    at buckets/apr_buckets_socket.c:36
#4  0x08086a98 in ap_core_input_filter (f=0x8165770, b=0x8165730,
    mode=AP_MODE_READBYTES, block=APR_NONBLOCK_READ, readbytes=5)
    at core_filters.c:235
#5  0xb7ce732a in bio_filter_in_read (bio=0x81666d8, in=0x816bc83 "", inlen=5)
    at ssl_engine_io.c:487
#6  0xb7b1bc66 in BIO_read ()
   from /home/joachima/httpd-2.4.18/lib/libcrypto.so.1.0.0
#7  0xb7c8e040 in ssl3_read_n ()
   from /home/joachima/httpd-2.4.18/lib/libssl.so.1.0.0
#8  0xb7c8fa75 in ssl3_read_bytes ()
   from /home/joachima/httpd-2.4.18/lib/libssl.so.1.0.0
#9  0xb7c8c211 in ssl3_read ()
   from /home/joachima/httpd-2.4.18/lib/libssl.so.1.0.0
#10 0xb7ca8679 in SSL_read ()
   from /home/joachima/httpd-2.4.18/lib/libssl.so.1.0.0
#11 0xb7ce80d7 in ssl_io_input_read (inctx=inctx@entry=0x81636e8,
    buf=buf@entry=0x8163710 "GET /css/subpage.css HTTP/1.1\r\nUser-Agent: 
curl/7.40.0\r\nHost: na171\r\nAccept: */*\r\n\r\n", len=len@entry=0xbffff8f8)
    at ssl_engine_io.c:611
#12 0xb7cea36c in ssl_io_filter_input (f=0x8165718, bb=0x81660d8,
    mode=AP_MODE_SPECULATIVE, block=APR_NONBLOCK_READ, readbytes=1)
    at ssl_engine_io.c:1407
#13 0x080a013f in check_pipeline (bb=0x81660d8, c=0x8156eb0)
    at http_request.c:244
#14 ap_process_request_after_handler (r=0x817e2d8) at http_request.c:367
#15 0x080a1229 in ap_process_async_request (r=r@entry=0x817e2d8)
    at http_request.c:448
#16 0x080a1575 in ap_process_request (r=r@entry=0x817e2d8)
    at http_request.c:458
#17 0x0809d547 in ap_process_http_sync_connection (c=0x8156eb0)
    at http_core.c:210
#18 ap_process_http_connection (c=0x8156eb0) at http_core.c:251
#19 0x0809549d in ap_run_process_connection (c=0x8156eb0) at connection.c:41
#20 0x0809589d in ap_process_connection (c=c@entry=0x8156eb0, csd=0x8156d18)
    at connection.c:213
#21 0x080a7849 in child_main (child_num_arg=child_num_arg@entry=0,
    child_bucket=child_bucket@entry=0) at prefork.c:723
#22 0x080a7a9f in make_child (s=0x80f9f38, slot=slot@entry=0,
    bucket=bucket@entry=0) at prefork.c:767
#23 0x080a9091 in prefork_run (_pconf=0x80d50a8, plog=0x80fd9b8, s=0x80f9f38)
    at prefork.c:979
#24 0x08070959 in ap_run_mpm (pconf=pconf@entry=0x80d50a8, plog=0x80fd9b8,
    s=0x80f9f38) at mpm_common.c:94
#25 0x08069f23 in main (argc=4, argv=0xbffffd54) at main.c:777



On 2016-02-03 11:50 PM, Plüm, Rüdiger, Vodafone Group wrote:

Can you also post the backtrace when the server is hanging in the read?

Regards

Rüdiger

-----Original Message-----
From: Plüm, Rüdiger, Vodafone Group
Sent: Donnerstag, 4. Februar 2016 08:39
To: dev@httpd.apache.org
Subject: RE: HTTPS connections lock-up with 2.4.18

Thanks. Which version of APR / APR-UTIL are you using?

Regards

Rüdiger

-----Original Message-----
From: Joachim Achtzehnter [mailto:joac...@kraut.ca]
Sent: Donnerstag, 4. Februar 2016 03:56
To: dev@httpd.apache.org
Subject: Re: HTTPS connections lock-up with 2.4.18

Perhaps, there is an important clue this time. When I retrieve a file
that works we see the following log messages near the time when the
reply is being written:

[Wed Feb 03 18:13:51.402289 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9dabd50] out: pass 271 bytes

[Wed Feb 03 18:13:51.402463 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9dabd50] out: pass 4020 bytes

[Wed Feb 03 18:13:51.402515 2016] [core:notice] [pid 1676] [client

205.159.216.185:55978] core_output_filter: sent 4291 on 4291 bytes

[Wed Feb 03 18:13:51.402527 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9dabd50] out: METADATA EOS

[Wed Feb 03 18:13:51.402581 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9dabd50] out: METADATA EOR

[Wed Feb 03 18:13:51.406356 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9db96d8] in: read 5 bytes

[Wed Feb 03 18:13:51.406375 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9db96d8] in: read 26 bytes

[Wed Feb 03 18:13:51.406392 2016] [http:notice] [pid 1676] (70014)End

of

file found: [client 205.159.216.185:55978] check_pipeline: no data

[Wed Feb 03 18:13:51.406476 2016] [http:notice] [pid 1676] (70014)End

of

file found: [client 205.159.216.185:55978] check_pipeline:
data_in_input_filters = 0

[Wed Feb 03 18:13:51.406492 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9dabd50] out: METADATA FLUSH

[Wed Feb 03 18:13:51.406591 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9dabd50] out: METADATA FLUSH

[Wed Feb 03 18:13:51.406613 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9dabd50] out: METADATA EOC

[Wed Feb 03 18:13:51.406624 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9dabd50] out: pass 31 bytes

[Wed Feb 03 18:13:51.406673 2016] [ssl:notice] [pid 1676] [client

205.159.216.185:55978] bio[9dabd50] out: FLUSH

[Wed Feb 03 18:13:51.406723 2016] [core:notice] [pid 1676] [client

205.159.216.185:55978] core_output_filter: sent 31 on 31 bytes

[Wed Feb 03 18:13:51.406735 2016] [ssl:debug] [pid 1676]

ssl_engine_io.c(1029): [client 205.159.216.185:55978] AH02001:

Connection

closed to child 0 with standard shutdown (server localhost:443)

Notice the call to check_pipeline returns quickly. Now the same part of
the log for the failing file:

[Wed Feb 03 17:56:55.424124 2016] [ssl:notice] [pid 1663] [client

205.159.216.185:55962] bio[8158d50] out: pass 271 bytes

[Wed Feb 03 17:56:55.424192 2016] [ssl:notice] [pid 1663] [client

205.159.216.185:55962] bio[8158d50] out: pass 1727 bytes

[Wed Feb 03 17:56:55.424223 2016] [ssl:notice] [pid 1663] [client

205.159.216.185:55962] bio[8158d50] out: METADATA EOS

[Wed Feb 03 17:56:55.424235 2016] [ssl:notice] [pid 1663] [client

205.159.216.185:55962] bio[8158d50] out: METADATA EOR

[Wed Feb 03 18:09:56.652288 2016] [http:notice] [pid 1663]

(11)Resource

temporarily unavailable: [client 205.159.216.185:55962] check_pipeline:

no

data

[Wed Feb 03 18:09:56.652376 2016] [http:notice] [pid 1663]

(11)Resource

temporarily unavailable: [client 205.159.216.185:55962] check_pipeline:
data_in_input_filters = 0

[Wed Feb 03 18:09:56.652398 2016] [ssl:notice] [pid 1663] [client

205.159.216.185:55962] bio[8158d50] out: METADATA FLUSH

[Wed Feb 03 18:09:56.652444 2016] [core:notice] [pid 1663] [client

205.159.216.185:55962] core_output_filter: sent 1998 on 1998 bytes

[Wed Feb 03 18:09:56.652510 2016] [ssl:info] [pid 1663] (70014)End of

file found: [client 205.159.216.185:55962] AH01991: SSL input filter

read

failed.

[Wed Feb 03 18:09:56.652519 2016] [ssl:notice] [pid 1663] [client

205.159.216.185:55962] bio[8158d50] out: METADATA FLUSH

[Wed Feb 03 18:09:56.652525 2016] [ssl:notice] [pid 1663] [client

205.159.216.185:55962] bio[8158d50] out: METADATA EOC

[Wed Feb 03 18:09:56.652545 2016] [ssl:notice] [pid 1663] [client

205.159.216.185:55962] bio[8158d50] out: pass 31 bytes

[Wed Feb 03 18:09:56.652553 2016] [ssl:notice] [pid 1663] [client

205.159.216.185:55962] bio[8158d50] out: FLUSH

[Wed Feb 03 18:09:56.652568 2016] [core:notice] [pid 1663] [client

205.159.216.185:55962] core_output_filter: sent 31 on 31 bytes

[Wed Feb 03 18:09:56.652576 2016] [ssl:debug] [pid 1663]

ssl_engine_io.c(1029): [client 205.159.216.185:55962] AH02001:

Connection

closed to child 0 with standard shutdown (server localhost:443)

The check_pipeline call only returns when I kill the client. I first
noticed this in the debugger where httpd was sitting in a blocking read.
Somehow, in this case a blocking read is done instead of a non-blocking
read.

To be specific, it ended up in the do/while loop that calls read in
function apr_socket_recv (sendrecv.c), called from socket_bucket_read in
apr_buckets_socket.c, called from ap_core_input_filter in
core_filters.c. The block parameter was APR_NONBLOCK_READ, but this
didn't stop the lower-level functions from blocking, somehow. The
apr_socket_recv function seems to do the select version of reading based
on the APR_INCOMPLETE_READ flag in sock->options.

By the way, to answer an earlier question, this is a prefork server with
separate processes, not threaded.

Thanks,

Joachim


On 2016-02-03 8:06, Yann Ylavic wrote:

On Wed, Feb 3, 2016 at 4:53 PM, Yann Ylavic <ylavic....@gmail.com>

wrote:


I suggest you use the attached patch instead (replacing any previous
one), so that we log the output path taken when mod_ssl is in the
place.


Forgot about the casting issue (SSL_get_app_data) with your

compiler...

This v5 (attached) should compile fine.

And maybe take network traces on the server side?


That would be really nice too.


Thanks,
Yann.


--
joac...@kraut.ca http://www.kraut.ca



--
joac...@kraut.ca   www.kraut.ca

Re: HTTPS connections lock-up with 2.4.18

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