CentOS 6.4 x86_64
MySQL 5.6.20
mysql-connector-odbc-5.3.4-1.el6.x86_64
unixODBC 2.2.14
gcc 4.8.2
g++ 4.8.2
GNU make 3.8.1

I've tried pre-zabbix-2.2.6rc1-48164.tar.gz on the same environment just now, but this problem still exists, how can I solve this issue ??

Backtrace for easier searching:

  2705:20140819:140450.276 === Backtrace: ===
  2705:20140819:140450.287 15: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values](print_fatal_info+0x287) [0x46cb87]
  2705:20140819:140450.287 14: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values]() [0x46ce06]
  2705:20140819:140450.287 13: /lib64/libc.so.6() [0x35a2a329a0]
  2705:20140819:140450.287 12: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values](get_string+0x2f) [0x4764cf]
  2705:20140819:140450.287 11: /usr/lib64/libmyodbc5.so(sql_get_data+0x328) [0x7f6bb21368e8]
  2705:20140819:140450.287 10: /usr/lib64/libmyodbc5.so(+0x6138f) [0x7f6bb213738f]
  2705:20140819:140450.287 9: /usr/lib64/libmyodbc5.so(my_SQLExtendedFetch+0x4e6) [0x7f6bb21383e6]
  2705:20140819:140450.287 8: /usr/lib64/libodbc.so.2(SQLFetch+0x103) [0x7f6bbe5d8713]
  2705:20140819:140450.287 7: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values](odbc_DBfetch+0x44) [0x49fb44]
  2705:20140819:140450.287 6: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values](get_value_db+0xd8) [0x42ecc8]
  2705:20140819:140450.287 5: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values]() [0x42753c]
  2705:20140819:140450.287 4: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values](main_poller_loop+0x92) [0x427702]
  2705:20140819:140450.287 3: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values](MAIN_ZABBIX_ENTRY+0x7b7) [0x41a527]
  2705:20140819:140450.287 2: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values](daemon_start+0x1c4) [0x46c1a4]
  2705:20140819:140450.287 1: /lib64/libc.so.6(__libc_start_main+0xfd) [0x35a2a1ed1d]
  2705:20140819:140450.287 0: /usr/local/sbin/zabbix_server: poller #3 [got 1 values in 0.000233 sec, getting values]() [0x4150e5]

I could reproduce the issue on our Debian 6.0, which has unixODBC 2.2.14 and a manually downloaded MySQL ODBC connector 5.3.4 (from http://dev.mysql.com/downloads/connector/odbc/).

So what we have is zabbix_server, which links to libodbc.so. That library loads libmyodbc5w.so dynamically. That MySQL driver library has global function get_string(), but the problem is that zabbix_server also has global function get_string(). So when the linker loads libmyodbc5w.so and tries to resolve "get_string" symbol, it resolves it to the function in zabbix_server (see http://stackoverflow.com/questions/6538501/linking-two-shared-libraries-with-some-of-the-same-symbols). When called, our get_string() crashes, as we can see from the backtrace.

Note that get_string() is not used by zabbix_server. Rather, it is a function that is currently used by zabbix_sender only. Here is what dlopen() manual at http://man7.org/linux/man-pages/man3/dlsym.3.html has to say:

External references in the library are resolved using the libraries in that library's dependency list and any other libraries previously opened with the RTLD_GLOBAL flag. If the executable was linked with the flag "-rdynamic" (or, synonymously, "--export-dynamic"), then the global symbols in the executable will also be used to resolve references in a dynamically loaded library.

Currently, we compile zabbix_server with "-rdynamic", but if we recompile the server without that option, the problem does not manifest.

Anyhow, we need "-rdynamic" to get crash backtraces. So the proposed solution is to make get_string() function static in zabbix_sender.c and try to prefix all global functions with "zbx_" in the future.

Note that it seems to work fine with libmyodbc 5.1.x, which is currently available in Debian packages.

Fixed in development branch svn://svn.zabbix.com/branches/dev/ZBX-8629 .

Thanks a lot for locating this problem, these information is very helpful to me !

According to your advice, I've modified source files of common.h (line 847), str.c (line 1878, 1895) and zabbix_sender.c (line 445, 465, 474, 486), changed get_string to zbx_get_string, then I compiled and installed Zabbix 2.2.5 with the same options in the same environment (CentOS 6.4 x86_64) as described before.

Now, I can get monitoring data of MySQL by items of "Database monitor" type !

Fixed in pre-2.0.13 r48311, pre-2.2.6 r48313, and pre-2.3.4 (trunk) r48314.