_G write guard whines about zlib being global and could cause race conditions

[Raw1mage]

when I do this

    local zlib = require ("zlib")

nginx error log would show:
[warn] 30914#30914: *24397 [lua] _G write guard:12: writing a global lua variable ('zlib') which may lead to race conditions between concurrent requests, so prefer the use of 'local' variables
stack traceback:
[C]: at 0x7f165255b755
[C]: in function 'require'

any light ?

[brimworks]

Maybe because we use the old luaL_register function when we should be using luaL_setfuncs?

https://github.com/brimworks/lua-zlib/blob/master/lua_zlib.c#L1263

Feel free to issue a pull request if this change fixes your issue.

Thanks!
-Brian

[davidguerreroprezi]

I had the same issue and could fix it by replacing the luaL_register with this:

lua_newtable(L);
luaL_setfuncs(L, zlib_functions, 0);

It works when importing from openresty (luajit), but not from standalone Lua 5.1

[brimworks]

Perhaps a little "macro magic" could solve this problem? Pull requests are welcomed :).

[a652]

I had the same issue with lua-zlib-1.2

[howiezhao]

If you use OpenResty, maybe can refer to this openresty/openresty#510 as a workaround.