successive writes are lost

Steven Grimm sgrimm at facebook.com
Wed Jan 24 22:00:53 UTC 2007


Any chance you can send your test program to me? If I can reproduce 
that, I'll definitely work on fixing it. We haven't noticed that 
behavior but I suppose if it's a rare condition, it might have been 
happening infrequently enough to escape our attention.

Which version of memcached are you running against?

-Steve


Jan Pfeifer wrote:
> hi,
>
> I was re-running some performance test, after a friend commented that memcache lost some writes  in some cases. 
>
> I
> noticed that if I do a program to write 50k entries (keys are the
> number 1 to 50000 in string format, and values are a 100 chars string)
> in a 500mb cache (enough space), I only get ~65% of them written
> (according to "stats items" and to the cache miss ratio I get after
> writting). 
>
> But, if I do a 10microsec pause in between each write, they all get through without a problem.
>
> I
> edited the server, and adding a few printf's I noticed that item_alloc
> and slab_alloc are called the 50k times, and return an ok results
> ("STORED").
>
>
> any ideas of what is happening, and how can we avoid this ? 
>
>
> thanks :)
>
> - jan
>
>
>
>
>
>
>
>
>  
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