Memcached on a shared host

Aaron Stone aaron at
Thu Apr 17 16:38:45 UTC 2008

On Apr 17, 2008, at 9:04 AM, mike wrote:
> On 4/17/08, Peter J. Holzer <hjp at> wrote:
>> Use a unix domain socket and set the permissions accordingly.
> duh, didn't think about suggesting that. however, having a local
> socket doesn't make sense if this is supposed to be *distributed* -
> use APC (in PHP) or some other local caching mechanism if you don't
> plan on distributing it!
>> But in that case I'd use a different scheme: Tell your users to  
>> choose a
>> hard to guess prefix (for example, 16 random letters or digits) for
>> their keys. This will ensure that users cannot read or modify each
>> other's data unless they are told or can guess the prefix.
> thats originally how i was going to do it, except people can wreak
> havoc by issuing flush_all and such. depending on how many people use
> it, it could wreck the whole point of having the cache there...

memcached also adjusts itself to the workload, by way of how the slabs  
are allocated and used. If your users have radically different sizes  
of values that they're storing, it's going to make trouble for slab  
availability for other sizes. memcached does not resize these slabs  
after they're in use.


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