WARNING: Stack unwind information not available. Following frames may be wrong.
SSLEAY32!SSL_shutdown+0x4
LIBPQ!PQpingParams+0x1631
LIBPQ!PQfinish+0x11
nginx!dbd_pgsql_close+0x106 [c:\usr\src\dbd\postgresql\dbd_pgsql.c @ 279]
nginx!dbd_pgsql_cleanup+0x3d [c:\usr\src\dbd\postgresql\dbd_pgsql.c @ 296]
nginx!ngx_destroy_pool+0x36 [c:\msys\1.0\nginx-1.10\src\core\ngx_palloc.c @ 57]
nginx!ngx_worker_process_exit+0x176 [c:\msys\1.0\nginx-1.10\src\os\win32\ngx_process_cycle.c @ 850]
nginx!ngx_worker_process_cycle+0x526 [c:\msys\1.0\nginx-1.10\src\os\win32\ngx_process_cycle.c @ 753]
nginx!ngx_master_process_cycle+0x37 [c:\msys\1.0\nginx-1.10\src\os\win32\ngx_process_cycle.c @ 76]
nginx!main+0x45c [c:\msys\1.0\nginx-1.10\src\core\nginx.c @ 367]
nginx!__tmainCRTStartup+0x10b [f:\dd\vctools\crt_bld\self_x86\crt\src\crt0.c @ 278]
kernel32!RegisterWaitForInputIdle+0x49
Maybe this not bug in libpq, but, I turns him.