Why named shared memory zones
maccaday at gmail.com
Mon Sep 28 19:25:37 MSD 2009
Igor Sysoev wrote:
> On Mon, Sep 28, 2009 at 03:28:44PM +0300, Marcus Clyne wrote:
>> What's the purpose/benefit of naming shared memory zones in config files?
> Its names are used in other directives. For example, you may have
> several proxy_cache's.
I understand their use in other directives, but I was just wondering why
you actually need them in the directives.
For example, if you define several proxy caches, then each one would
automatically use a different shared memory section. It seems
unnecessary to me to use names in the config file, since they'd always
be different, and from what I gather, if you use the same name (and tag)
for two shared memory sections, then you'll get a conf error (correct me
if I'm wrong, though).
I feel that having the config like
proxy_cache_path /data/nginx/cache levels=1:2 10m;
proxy_cache_path /data/nginx/cache 1:2 10m;
would be much neater than
proxy_cache_path /data/nginx/cache levels=1:2 key_zone=one:10m;
And overall wouldn't lose any information that couldn't be generated in
> The second reason is Win32 uses named shared memory mapping.
> However, it's lamost impossible to use shared memory in Win32 due to
> Vista ASLR.
If you need to have named sections, it would be easy enough to generate
them sequentially (e.g. ngx_shms1, ngx_shms2...) whilst reading the
More information about the nginx