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Posted to bugs@httpd.apache.org by bu...@apache.org on 2013/05/16 20:34:28 UTC
[Bug 54986] New: httpd hanging on large form submit in
ap_run_handler
https://issues.apache.org/bugzilla/show_bug.cgi?id=54986
Bug ID: 54986
Summary: httpd hanging on large form submit in ap_run_handler
Product: Apache httpd-2
Version: 2.2.22
Hardware: PC
OS: Linux
Status: NEW
Severity: major
Priority: P2
Component: All
Assignee: bugs@httpd.apache.org
Reporter: rtomasso@yahoo.com
Classification: Unclassified
Have an issue with a customer system. The apache process is completely hanging
when trying to process a submitted form. It's a POST with a long list of mac
addresses, about 22K of total data. At some point this just stopped working.
Smaller submits, up to 20K work, the exact tripping point varies each time we
run it.
Running gdb and attaching to the httpd process (recompiled with -g3 flag) I see
this, with a breakpoint set at ap_run_handler.
(gdb) bt
#0 ap_run_handler (r=0xdd3bd50) at config.c:157
#1 0x0807990f in ap_invoke_handler (r=0xdd3bd50) at config.c:376
#2 0x08094d45 in ap_process_request (r=0xdd3bd50) at http_request.c:282
#3 0x0dd3bd50 in ?? ()
#4 0x0d632440 in ?? ()
#5 0x00000000 in ?? ()
(gdb) s
And it just hangs. I can't see what r is pointing to.
I find no function definition in the apache source tree for ap_run_handler().
Line 157 in config.c is
AP_IMPLEMENT_HOOK_RUN_FIRST(int, handler, (request_rec *r), (r), DECLINED)
Following the code for definitions of this macro, leads me to a rather
obfuscated define in apr_hooks.h, line 358
/** macro to implement the hook */
#define APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
link##_DECLARE(void) ns##_hook_##name(ns##_HOOK_##name##_t *pf,const char *
const *aszPre, \
const char * const *aszSucc,int nOrder) \
{ \
The apache docs are no help, simply notes it as an internal macro.
# uname -a
Linux lab01.net 2.6.18-238.9.1.el5 #1 SMP Tue Apr 12 18:10:13 EDT 2011 x86_64
x86_64 x86_64 GNU/Linux
(I think this is CentOS 5.7)
# httpd -V
Server version: Apache/2.2.22 (Unix)
Server built: May 13 2013 11:55:26
Server's Module Magic Number: 20051115:30
Server loaded: APR 1.4.5, APR-Util 1.3.12
Compiled using: APR 1.4.5, APR-Util 1.4.1
Architecture: 32-bit
Server MPM: Prefork
threaded: no
forked: yes (variable process count)
Server compiled with....
-D APACHE_MPM_DIR="server/mpm/prefork"
-D APR_HAS_SENDFILE
-D APR_HAS_MMAP
-D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
-D APR_USE_SYSVSEM_SERIALIZE
-D APR_USE_PTHREAD_SERIALIZE
-D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
-D APR_HAS_OTHER_CHILD
-D AP_HAVE_RELIABLE_PIPED_LOGS
-D DYNAMIC_MODULE_LIMIT=128
-D HTTPD_ROOT="/space/vendor-build/apache"
-D SUEXEC_BIN="/space/vendor-build/apache/bin/suexec"
-D DEFAULT_PIDLOG="logs/httpd.pid"
-D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
-D DEFAULT_LOCKFILE="logs/accept.lock"
-D DEFAULT_ERRORLOG="logs/error_log"
-D AP_TYPES_CONFIG_FILE="conf/mime.types"
-D SERVER_CONFIG_FILE="conf/httpd.conf"
# httpd -l
Compiled in modules:
core.c
mod_ssl.c
prefork.c
http_core.c
mod_so.c
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[Bug 54986] httpd hanging on large form submit in ap_run_handler
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54986
--- Comment #5 from Rich <rt...@yahoo.com> ---
I set breakpoints at ap_hook_handler and default_handler, neither of them were
reached.
I ran the same form with a small data set so it completed. At the breakpoint
for ap_run_handler, I did step and it came back quickly with the next line
further down, a call to ap_invoke_handler [config.c:378]. And the form has
returned. No meaningful difference in contents of the request object.
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[Bug 54986] httpd hanging on large form submit in ap_run_handler
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54986
--- Comment #4 from Mike Rumph <mi...@oracle.com> ---
(In reply to comment #0)
> I find no function definition in the apache source tree for
> ap_run_handler().
>
> Line 157 in config.c is
> AP_IMPLEMENT_HOOK_RUN_FIRST(int, handler, (request_rec *r), (r), DECLINED)
>
> Following the code for definitions of this macro, leads me to a rather
> obfuscated define in apr_hooks.h, line 358
> /** macro to implement the hook */
> #define APR_IMPLEMENT_EXTERNAL_HOOK_BASE(ns,link,name) \
> link##_DECLARE(void) ns##_hook_##name(ns##_HOOK_##name##_t *pf,const char *
> const *aszPre, \
> const char * const *aszSucc,int
> nOrder) \
> { \
>
> The apache docs are no help, simply notes it as an internal macro.
>
The function to look for is ap_hook_handler.
This is found in several modules.
One example is server/core.c:
ap_hook_handler(default_handler,NULL,NULL,APR_HOOK_REALLY_LAST);
This will cause the default_handler function in core.c to be called whenever
ap_run_handler is called.
The following documentation may help explain this:
- http://httpd.apache.org/docs/2.2/developer/hooks.html
Perhaps mod_perl should have something like this as well.
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[Bug 54986] httpd hanging on large form submit in ap_run_handler
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54986
Eric Covener <co...@gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |NEEDINFO
--- Comment #1 from Eric Covener <co...@gmail.com> ---
What handler/module is expected to process this request? Usually the body
isn't read until the handler has control. Can you try again with -O0 and don't
set a breakpoint, just get a backtrace of the hung thread.
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[Bug 54986] httpd hanging on large form submit in ap_run_handler
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54986
Rich <rt...@yahoo.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEEDINFO |NEW
--- Comment #2 from Rich <rt...@yahoo.com> ---
We're running in a mod_perl environment. If I let the process hang I can't get
a backtrace.
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[Bug 54986] httpd hanging on large form submit in ap_run_handler
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=54986
--- Comment #3 from Rich <rt...@yahoo.com> ---
Rebuilt with the -O0 option I was able to get some more information. In this
environment the doc root is "/opt/product/apache/htdocs".
(gdb) bt
#0 ap_run_handler (r=0xce37d20) at config.c:157
#1 0x0807fb5c in ap_invoke_handler (r=0xce37d20) at config.c:376
#2 0x080a33b2 in ap_process_request (r=0xce37d20) at http_request.c:282
#3 0x080a06e0 in ap_process_http_connection (c=0xcb53d08) at http_core.c:190
#4 0x08086b8f in ap_run_process_connection (c=0xcb53d08) at connection.c:43
#5 0x08086fe5 in ap_process_connection (c=0xcb53d08, csd=0xcb53b70) at
connection.c:190
#6 0x080a9490 in child_main (child_num_arg=0) at prefork.c:667
#7 0x080a963c in make_child (s=0x8dd2ca8, slot=0) at prefork.c:768
#8 0x080a96af in startup_children (number_to_start=1) at prefork.c:786
#9 0x080a9ae0 in ap_mpm_run (_pconf=0x8dce0a8, plog=0x8e04180, s=0x8dd2ca8) at
prefork.c:1007
#10 0x08069dd1 in main (argc=3, argv=0xffa79174) at main.c:753
(gdb) p r
$1 = (request_rec *) 0xce37d20
(gdb) p *r
$2 = {pool = 0xce37ce0, connection = 0xcb53d08, server = 0x8dd2ca8, next = 0x0,
prev = 0x0, main = 0x0,
the_request = 0xce38c60 "POST /sla/create/index.html HTTP/1.1", assbackwards
= 0, proxyreq = 0, header_only = 0,
protocol = 0xce38d00 "HTTP/1.1", proto_num = 1001, hostname = 0xce39220
"209.211.205.181",
request_time = 1369158013800915, status_line = 0x0, status = 200, method =
0xce38cb0 "POST", method_number = 2,
allowed = 0, allowed_xmethods = 0x0, allowed_methods = 0xce37ec0, sent_bodyct
= 0, bytes_sent = 0, mtime = 0,
chunked = 0, range = 0x0, clength = 0, remaining = 0, read_length = 0,
read_body = 0, read_chunked = 0,
expecting_100 = 0, headers_in = 0xce37ef0, headers_out = 0xce38380,
err_headers_out = 0xce38528,
subprocess_env = 0xce38138, notes = 0xce38680, content_type = 0x8e90c48
"text/html",
handler = 0x8ded1c8 "perl-script", content_encoding = 0x0, content_languages
= 0x0, vlist_validator = 0x0,
user = 0x0, ap_auth_type = 0x0, no_cache = 0, no_local_copy = 0,
unparsed_uri = 0xce38cd0 "/sla/create/index.html", uri = 0xce38ce8
"/sla/create/index.html",
filename = 0xce39348 "/opt/product/apache/htdocs/sla/create/index.html",
canonical_filename = 0xce39348
"/opt/product/apache/htdocs/sla/create/index.html", path_info = 0xce392c1 "",
args = 0x0, finfo = {pool = 0xce37ce0, valid = 7598960, protection = 1604,
filetype = APR_REG, user = 504,
group = 110, inode = 6657732, device = 64769, nlink = 1, size = 2608, csize
= 4096, atime = 1369157418000000,
mtime = 1360861380000000, ctime = 1360861380000000,
fname = 0xce39290 "/opt/product/apache/htdocs/sla/create/index.html", name
= 0x0, filehand = 0x0}, parsed_uri = {
scheme = 0x0, hostinfo = 0x0, user = 0x0, password = 0x0, hostname = 0x0,
port_str = 0xce39239 "8080",
path = 0xce38ce8 "/sla/create/index.html", query = 0x0, fragment = 0x0,
hostent = 0x0, port = 8080,
is_initialized = 1, dns_looked_up = 0, dns_resolved = 0}, used_path_info =
2, per_dir_config = 0xce39590,
request_config = 0xce387d8, htaccess = 0x0, output_filters = 0xccf1818,
input_filters = 0xce39240,
proto_output_filters = 0xce38be0, proto_input_filters = 0xce39240, eos_sent =
0}
Stepping from here, the process hangs. Running pstack from another window
returns nothing.
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