Segfault when re-adding server after resetServerList() and using DISTRIBUTION=CONSISTENT

[arjenschol]

Testscript and backtrace @ https://gist.github.com/arjenschol/5729158

[arjenschol]

php 5.4.16
php-memcached 2.1.0
libmemcached 1.0.16
Archlinux 3.9.3-1

[degtyaryov]

Hello.

setOption(Memcached::OPT_LIBKETAMA_COMPATIBLE, true); var_dump($m->addServer($host, $port, $weight)); var_dump($m->resetServerList()); var_dump($m->addServer($host, $port, $weight)); var_dump($m->getServerList()); ?>

this is promlem exists on fedora 19:
memcached-1.4.15-4.fc19.x86_64
php-pecl-memcached-2.1.0-7.fc19.x86_64
libmemcached-1.0.16-1.fc19.x86_64
php-cli-5.5.3-1.fc19.x86_64

$ php test.php
bool(true)
bool(true)
Segmentation fault

(gdb) bt
#0 0x00007fffe2b36b31 in update_continuum(memcached_st*) () from /lib64/libmemcached.so.11
#1 0x00007fffe2b374a5 in memcached_server_add_with_weight () from /lib64/libmemcached.so.11
#2 0x00007fffe2d5d3a5 in zim_Memcached_addServer () from /usr/lib64/php/modules/memcached.so
#3 0x00005555557714fb in dtrace_execute_internal ()
#4 0x0000555555831245 in zend_do_fcall_common_helper_SPEC ()
#5 0x00005555557ab0b8 in execute_ex ()
#6 0x00005555557713d9 in dtrace_execute_ex ()
#7 0x0000555555782e30 in zend_execute_scripts ()
#8 0x0000555555722b05 in php_execute_script ()
#9 0x0000555555833258 in do_cli ()
#10 0x000055555560dc50 in main ()

on fedora 18 no problem:
memcached-1.4.15-2.fc18.x86_64
libmemcached-1.0.8-2.fc18.x86_64
php-pecl-memcached-2.1.0-3.fc18.x86_64
php-cli-5.4.17-2.fc18.x86_64

$ php test.php
bool(true)
bool(true)
bool(true)
array(1) {
[0]=>
array(2) {
["host"]=>
string(9) "localhost"
["port"]=>
int(11211)
}
}

how to solve this problem?

Thanks.

[degtyaryov]

backtrace with debuginfo:

(gdb) bt
#0 0x00007fffe2b36b31 in update_continuum (ptr=0x555555f847d0) at libmemcached/hosts.cc:316
#1 0x00007fffe2b374a5 in memcached_server_add_with_weight (shell=0x555555f847d0, hostname=0x7fffbe2d95a0 "localhost", port=11211, weight=0) at libmemcached/hosts.cc:585
#2 0x00007fffe2d5d3a5 in zim_Memcached_addServer () from /usr/lib64/php/modules/memcached.so
#3 0x00005555557714fb in dtrace_execute_internal ()
#4 0x0000555555831245 in zend_do_fcall_common_helper_SPEC ()
#5 0x00005555557ab0b8 in execute_ex ()
#6 0x00005555557713d9 in dtrace_execute_ex ()
#7 0x0000555555782e30 in zend_execute_scripts ()
#8 0x0000555555722b05 in php_execute_script ()
#9 0x0000555555833258 in do_cli ()
#10 0x000055555560dc50 in main ()

[degtyaryov]

this problem is only present with libmemcached-1.0.16! with libmemcached-1.0.8 all correct.

https://bugs.launchpad.net/libmemcached/+bug/1154159

[mkoppanen]

Looks like an upstream issue.

[sodabrew]

Closing because this was verified as a bug in libmemcached 1.0.16.

[ukautz]

If somebody else stumbles across this: I am experiencing this exact issue with libmemached 1.0.18. It's not a php-memcached bug, for sure.

How to fix: In the above mentioned Launchpad page the "continuum patch" linked, which fixes the issue as far as I can tell. It's not part of the official version 1.0.18, though.