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From "Chris Anderson" <>
Subject Re: Write Performance
Date Thu, 08 Jan 2009 00:47:08 GMT
On Wed, Jan 7, 2009 at 4:37 PM, Josh Bryan <> wrote:
> Hi,
> I am looking into CouchDB as a solution to store a bunch (approx 70
> million) archived documents.  While planning for the import process, I
> did some benchmarking to figure out how long the import will take.  I
> get about 50-70 inserts per second on average.  However, when I looked
> for the bottleneck, I couldn't figure it out.  I am connected to the
> database via a fast lan and can verify that the network is not
> saturated.  I can also verify that disk IO is not saturated.  The only
> clue is that of the 4 cpus on the server, it seems that only one is
> getting fully loaded.  Also, of the 5 erlang processes I can see
> running, only one of them seems to be getting most of the cpu time.  I
> know that erlang is built with smp enabled, so if it is cpu bound, why
> can't it make use of the other 3 processors?
> I thought that perhaps there was some internal write lock issue per
> database that allowed only one thread to write to a db at a time, so I
> tried running the benchmarks while hitting multiple databases, but still
> got the same write rate across the databases.  Is there some globally
> shared resource in couchdb that limits all writes to a single thread?
> Thanks,
> Josh

Before we can help you diagnose the performance you're seeing, could
you tell us the version of CouchDB and the version of Erlang that you
are using? It wouldn't hurt to describe the hardware in more detail

Chris Anderson

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