PHP :: Bug #8446 :: PHP/apache process is in infinite loop or appears to suck CPU

Bug #8446	PHP/apache process is in infinite loop or appears to suck CPU
Submitted:	2000-12-27 19:31 UTC	Modified:	2001-04-10 09:39 UTC
From:	michael at audiogalaxy dot com	Assigned:
Status:	Closed	Package:	*General Issues
PHP Version:	4.0.4	OS:	RH 7.0 and RH 6.2 Any kernel 2.2
Private report:	No	CVE-ID:	None

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From:	michael at audiogalaxy dot com
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[2000-12-27 19:31 UTC] michael at audiogalaxy dot com

Below is a report from top for a SMP machine.  This happens to all of our webservers every day or so a few machine have one two httpd processes eating CPU.  This same problem also happens on the last two or more previous versions of php.  

A simple kill -9 pid removes it w/o killing the whole webserver.  Below are the apache and httpd configuration lines:

./configure --with-mysql --enable-track-vars --with-zlib --with-apache=$apachedir --with-gd=$gddir --with-jpeg-dir=$gddir --with-config-file-path=/common/globalconfig/php --enable-memory-limit

./configure --with-layout=production --activate-module=src/modules/php4/libphp4.a

An interesting aspect that is amount of memory each processing using 100% CPU is around 50megs.  We have the memory limit set in php as 30M.

1 processes: 85 sleeping, 6 running, 0 zombie, 0 stopped
CPU0 states: 70.0% user,  4.0% system,  0.0% nice, 25.0% idle
CPU1 states: 53.0% user,  4.0% system,  0.0% nice, 41.0% idle
Mem:  1036464K av, 1006188K used,   30276K free,  149244K shrd,   32068K buff
Swap:  136512K av,    1124K used,  135388K free                  677272K cached

  PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
 7763 nobody     9   0 53808  52M  2172 R    99.9  5.1  1527m httpd
 6825 nobody     0   0  4320 4320  2272 S     9.2  0.4   0:00 httpd
 6779 nobody     0   0  4912 4912  2276 S     6.4  0.4   0:00 httpd
 6830 root       4   0  1036 1036   812 R     6.4  0.0   0:00 top


Thanks for your help - this has been a real nagging problem for us that we keep thinking is resolved in the next version.

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[2000-12-28 05:31 UTC] derick@php.net

Rasmus replyed:

We cannot possibly track this down for you based on this.  You will need
to attach gdb to one of these looped processes and see where it is
looping.

[2000-12-28 14:04 UTC] michael at audiogalaxy dot com

Below is the requested information on one of the processes.  I am not running php with --enable-debug - is this a problem?  Should I go back and recompile everything?
Thanks

Attaching to program: /usr/sbin/httpd, Pid 28916
0x2ac1ce2b in ?? ()
(gdb) bt
#0  0x2ac1ce2b in ?? ()
#1  0x2ac1cc94 in ?? ()
#2  0x80dcf59 in do_foreach_cont (value=0xb4b201c, key=0x2acbe8a0, as_token=0x80eecb8) at zend_compile.c:2095
#3  0x80dd41b in do_extended_fcall_begin () at zend_compile.c:2291
#4  0x807e708 in php_execute_script (primary_file=0x0) at main.c:1150
#5  0x807e6bb in php_execute_script (primary_file=0x81a5920) at main.c:1144
#6  0x807cdb5 in php_info_apache (zend_module=0x81ea024) at php_apache.c:269
#7  0x812556e in usage ()
#8  0x812b4fb in ap_read_request ()
#9  0x812e0b2 in ap_rprintf ()
#10 0x812e6fb in ap_send_error_response ()
#11 0x812ea78 in ap_send_error_response ()
#12 0x812efdd in check_safe_file ()
#13 0x812f607 in directory_walk ()
#14 0x2abbae21 in ?? ()

[2001-01-02 09:25 UTC] sniper@php.net

Yes, you should reconfigure/compile php with --enable-debug
in configure line. And please add also shortest possible
script which causes this infinite loop.

--Jani

[2001-01-10 05:02 UTC] michael at audiogalaxy dot com

I now added the --enable-debug and here are the following backtraces I get when php/apache is stuck:

example1:
Attaching to program: /usr/sbin/httpd, Pid 3193
0x2ac1d671 in ?? ()
(gdb) bt
#0  0x2ac1d671 in ?? ()
#1  0x2ac1d4d4 in ?? ()
#2  0x81016ca in normal_skipS (enc=0x1, ptr=0x0) at xmltok_impl.c:1694
#3  0x807efe7 in php_global_startup_internal_extensions () at internal_functions.c:68
#4  0x807c637 in init_request_info ()
#5  0x8150470 in utf8_toUtf8 ()
#6  0x814ed2a in normal_scanPoundName ()
#7  0x814edaa in normal_scanPoundName ()
#8  0x814ed16 in normal_scanPoundName ()
#9  0x815e41d in gdImageCopyMergeGray ()
#10 0x815eab3 in gdImageCreateFromXbm ()
#11 0x815ee30 in gdImageCreateFromXbm ()
#12 0x815f395 in gdImageSetTile ()
#13 0x815f9bf in gdImageCharUp ()
#14 0x2abbafd1 in ?? ()
(gdb) 



example2:
(gdb) bt
#0  0x2ac1ce26 in ?? ()
#1  0x2ac1cc94 in ?? ()
#2  0x81016ca in php_XmlInitUnknownEncoding (mem=0x1, table=0x0, convert=0x7ffff898, 
    userData=0x807efbd) at xmltok.c:1313
#3  0x807efe7 in do_cfg_op (type=42 '*', result=0x821cbb4, op1=0x7ffff8d8, op2=0x8153192)
    at configuration-parser.c:389
#4  0x807c637 in php_apache_value_handler_ex ()
#5  0x8150470 in big2_scanComment ()
#6  0x814ed2a in little2_prologTok ()
#7  0x814edaa in little2_prologTok ()
#8  0x815e895 in mime_cmds ()
#9  0x815eab3 in mime_cmds ()
#10 0x815ee30 in negotiation_cmds ()
#11 0x815f395 in status_options ()
#12 0x815f9bf in status_options ()
#13 0x2abbae21 in ?? ()
(gdb) 

Unfortunately there is no way I can attach a script that causes this bug because we have no clue when it happens and it happens only a few times a day on a site that gets 65 million page views per month.  We are using gd version 1.8.3

[2001-01-10 05:10 UTC] michael at audiogalaxy dot com

OOPS - please ignore my last post a few minutes on this - The debug symbols did not load properly.

example 1:
Attaching to program: /common/install/httpd, Pid 3193
Reading symbols from /lib/libpam.so.0...done.
Loaded symbols for /lib/libpam.so.0
Reading symbols from /lib/libdl.so.2...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /usr/lib/libz.so.1...done.
Loaded symbols for /usr/lib/libz.so.1
Reading symbols from /usr/lib/libpng.so.2...done.
Loaded symbols for /usr/lib/libpng.so.2
Reading symbols from /usr/lib/libjpeg.so.62...done.
Loaded symbols for /usr/lib/libjpeg.so.62
Reading symbols from /lib/libresolv.so.2...done.
Loaded symbols for /lib/libresolv.so.2
Reading symbols from /lib/libm.so.6...done.
Loaded symbols for /lib/libm.so.6
Reading symbols from /lib/libcrypt.so.1...done.
Loaded symbols for /lib/libcrypt.so.1
Reading symbols from /lib/libnsl.so.1...done.
Loaded symbols for /lib/libnsl.so.1
Reading symbols from /lib/libc.so.6...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /lib/libnss_files.so.2...done.
Loaded symbols for /lib/libnss_files.so.2
Reading symbols from /lib/libnss_nisplus.so.2...done.
Loaded symbols for /lib/libnss_nisplus.so.2
Reading symbols from /lib/libnss_nis.so.2...done.
Loaded symbols for /lib/libnss_nis.so.2
0x2ac1d66e in chunk_free (ar_ptr=0x2acc1f00, p=0xcc1f570) at malloc.c:3142
3142    malloc.c: No such file or directory.
(gdb) bt
#0  0x2ac1d66e in chunk_free (ar_ptr=0x2acc1f00, p=0xcc1f570) at malloc.c:3142
#1  0x2ac1d4d4 in __libc_free (mem=0xcc1f5b8) at malloc.c:3044
#2  0x81016ca in shutdown_memory_manager (silent=1, clean_cache=0) at zend_alloc.c:478
#3  0x807efe7 in php_request_shutdown (dummy=0x0) at main.c:695
#4  0x807c637 in php_apache_request_shutdown ()
#5  0x8150470 in run_cleanups ()
#6  0x814ed2a in ap_clear_pool ()
#7  0x814edaa in ap_destroy_pool ()
#8  0x814ed16 in ap_clear_pool ()
#9  0x815e41d in child_main ()
#10 0x815eab3 in make_child ()
#11 0x815ee30 in perform_idle_server_maintenance ()
#12 0x815f395 in standalone_main ()
#13 0x815f9bf in main ()
#14 0x2abbafd1 in __libc_start_main (main=0x815f628 <main>, argc=1, ubp_av=0x7ffffb64, 
    init=0x8064de0 <_init>, fini=0x819338c <_fini>, rtld_fini=0x2aab9254 <_dl_fini>, 
    stack_end=0x7ffffb5c) at ../sysdeps/generic/libc-start.c:118
(gdb) 


example 2:
Attaching to program: /common/install/httpd, Pid 13835
Reading symbols from /lib/libpam.so.0...done.
Loaded symbols for /lib/libpam.so.0
Reading symbols from /lib/libdl.so.2...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /usr/lib/libz.so.1...done.
Loaded symbols for /usr/lib/libz.so.1
Reading symbols from /usr/lib/libpng.so.2...done.
Loaded symbols for /usr/lib/libpng.so.2
Reading symbols from /usr/lib/libjpeg.so.62...done.
Loaded symbols for /usr/lib/libjpeg.so.62
Reading symbols from /lib/libresolv.so.2...done.
Loaded symbols for /lib/libresolv.so.2
Reading symbols from /lib/libm.so.6...done.
Loaded symbols for /lib/libm.so.6
Reading symbols from /lib/libcrypt.so.1...done.
Loaded symbols for /lib/libcrypt.so.1
Reading symbols from /lib/libnsl.so.1...done.
Loaded symbols for /lib/libnsl.so.1
Reading symbols from /lib/libc.so.6...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /lib/libnss_files.so.2...done.
Loaded symbols for /lib/libnss_files.so.2
Reading symbols from /lib/libnss_nisplus.so.2...done.
Loaded symbols for /lib/libnss_nisplus.so.2
Reading symbols from /lib/libnss_nis.so.2...done.
Loaded symbols for /lib/libnss_nis.so.2
Reading symbols from /lib/libnss_dns.so.2...done.
Loaded symbols for /lib/libnss_dns.so.2
0x2ac1ce26 in chunk_free (ar_ptr=0x2acbe8a0, p=0x82a5ff0) at malloc.c:3142
3142    malloc.c: No such file or directory.
(gdb) bt
#0  0x2ac1ce26 in chunk_free (ar_ptr=0x2acbe8a0, p=0x82a5ff0) at malloc.c:3142
#1  0x2ac1cc94 in __libc_free (mem=0x82a6050) at malloc.c:3044
#2  0x81016ca in shutdown_memory_manager (silent=1, clean_cache=0) at zend_alloc.c:478
#3  0x807efe7 in php_request_shutdown (dummy=0x0) at main.c:695
#4  0x807c637 in php_apache_request_shutdown ()
#5  0x8150470 in run_cleanups ()
#6  0x814ed2a in ap_clear_pool ()
#7  0x814edaa in ap_destroy_pool ()
#8  0x815e895 in child_main ()
#9  0x815eab3 in make_child ()
#10 0x815ee30 in perform_idle_server_maintenance ()
#11 0x815f395 in standalone_main ()
#12 0x815f9bf in main ()
#13 0x2abbae21 in __libc_start_main (main=0x815f628 <main>, argc=1, ubp_av=0x7ffffb64, 
    init=0x8064de0 <_init>, fini=0x819338c <_fini>, rtld_fini=0x2aab8f94 <_dl_fini>, 
    stack_end=0x7ffffb5c) at ../sysdeps/generic/libc-start.c:111
(gdb) 


This also looks like the same bug as #8618

Thanks

[2001-01-12 22:58 UTC] michael at audiogalaxy dot com

Another example - this time where memory usage is low while eating as much CPU as it can:

Reading symbols from /lib/libnss_nis.so.2...done.
Loaded symbols for /lib/libnss_nis.so.2
0x2ac1ce20 in chunk_free (ar_ptr=0x2acbe8a0, p=0x82097a0) at malloc.c:3142
3142    malloc.c: No such file or directory.
(gdb) bt
#0  0x2ac1ce20 in chunk_free (ar_ptr=0x2acbe8a0, p=0x82097a0) at malloc.c:3142
#1  0x2ac1cc94 in __libc_free (mem=0x8209958) at malloc.c:3044
#2  0x80eb4bb in zend_hash_destroy (ht=0x81d0b00) at zend_hash.c:569
#3  0x807fee4 in php_shutdown_config () at php_ini.c:244
#4  0x807e6d5 in php_module_shutdown () at main.c:941
#5  0x807e6bb in php_module_shutdown_wrapper (sapi_globals=0x81a5920) at main.c:926
#6  0x807cdb5 in php_child_exit_handler ()
#7  0x812556e in ap_child_exit_modules ()
#8  0x812b4fb in clean_child_exit ()
#9  0x812e0b2 in child_main ()
#10 0x812e6fb in make_child ()
#11 0x812ea78 in perform_idle_server_maintenance ()
#12 0x812efdd in standalone_main ()
#13 0x812f607 in main ()
#14 0x2abbae21 in __libc_start_main (main=0x812f270 <main>, argc=2, ubp_av=0x7ffffb24, init=0x8064c2c <_init>, 
    fini=0x8162fdc <_fini>, rtld_fini=0x2aab8f94 <_dl_fini>, stack_end=0x7ffffb1c)
    at ../sysdeps/generic/libc-start.c:111
(gdb) q

[2001-03-04 16:11 UTC] sniper@php.net

Could you please try the latest CVS snapshot from http://snaps.php.net/ ?

--Jani

[2001-04-10 09:39 UTC] sniper@php.net

No feedback. If this happens with soon to be released PHP 4.0.5 too, reopen this bug report.

--Jani

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