> It's coming up pretty soon in my TODO list though; we've been catching up > on the backlog with 1.4.
Are you planning to implement this for version 1.6? On Tue, Sep 27, 2011 at 6:54 PM, dormando <[email protected]> wrote: >> This is an issue described on the memcached documentation: >> "...Unfortunately, slabs allocated early in memcached's process life >> might over time be effectively in the wrong slabclass. Imagine, for >> example, that you store session data in memcached, and memcached has >> been up and running for months. Finally, you deploy a new version of >> your application code, which stores more interesting information in >> your sessions -- so your session sizes have grown. Suddenly, memcached >> starts thrashing with huge amounts of evictions. What might have >> happened is that since the session size grew, the slab allocator needs >> to use a different slabclass. Most of the slabs are now sitting idle >> and unused in the old slabclass. The usual solution is to just restart >> memcached, unless you've turned on ALLOW_SLABS_REASSIGN..." >> >> We were having that same issue in many of our servers, and since >> ALLOW_SLABS_REASSING is no longer supported the only thing we could do >> was to restart the servers, which lead to a storm of cache misses and >> other operational issues for us. >> That's why we developed an experimental command named "drop_slab" >> which when run just deletes all values in a slab class and deallocates >> that memory returning it to the OS. >> >> My question are: >> a) Has any of you run into this issue and if so how did you handle it? >> b) Do you think this command is something you would use? If so I can >> submit a patch. I'm planning to port it to version 1.6 (currently is >> for version 1.4) > > Yes, we're aware of this. Feel free to post your patch somewhere and talk > about it. > > However what we end up using for mainline is taking more time to develop > as it's difficult to do this automatically, correctly, for most users. > > It's coming up pretty soon in my TODO list though; we've been catching up > on the backlog with 1.4. > > -Dormando >
