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From sasha <>
Subject Re: Poor performance; PHP &amp; Thrift to blame
Date Fri, 20 Aug 2010 07:35:44 GMT
Julian Simon <jsimon <at>> writes:

> Hi,
> I've been trying to benchmark Cassandra for our use case and have been
> seeing poor performance on both writes and (extremely) poor
> performance on reads.
> Using Cassandra 0.51 stable & thrift-0.2.0.
> It turns out all the CPU time is going to the PHP client process - the
> JVM operating the Cassandra server isn't breaking much of a sweat.
> For reads the latency is often up to 1 second to fetch a row
> containing ~2000 columns, or around 300ms to fetch a 500-column wide
> row.  This is with get_slice(), and a predicate specifying the start &
> finish range.
> Using cachegrind and inspecting the code inside the Thrift bindings
> makes it pretty clear why the performance is so bad, particularly on
> reads. The biggest culprit is the translation code which casts data
> back and forth into binary representations for sending over the wire
> to the Cassandra server.
> There seems to be some 32-bit specific code which iterates heavily
> apparently due to a limitation in PHPs implementation of LONGs.
> However, testing on a 64-bit host doesn't yield any performance improvement.
> More surprisingly, if I compile and enable the PHP native thrift
> bindings (following this guide
> read performance actually degrades by another 50%.  I have verified
> that the Thrift code is recognizing and using the native PHP functions
> provided by the library.
> I've tested all of this on both 32-bit and 64-bit installations of
> both PHP 5.1 & 5.2.  Results are the same in all cases.
> My environment is on vanilla CentOS 5.4 server installations inside
> VMWare on a 4 core 64bit host with plenty of RAM and fast disks.
> Has anyone been able to produce decent performance with PHP &
> Cassandra?  If so, how have you done it?
> Thanks,
> Jules

I had exactly the same problem: without native thrift bindings the performance 
was low and PHP used too much CPU. But when I compiled 
and enabled the native thrift bindings (following this guide https://, the performance 
became even lower, it degraded SEVERAL TIMES (although CPU usage decreased too).

With the several random tries I discovered, that the buffer size matters. I 
mean the second and the third arguments for "new TBufferedTransport($socket, X, 
Y)". But the most surprising fact is that it matters much more when using 
native thrift bindings than when not using them.

- get_range_slices without native thrift bindings (either small or large buffer 
size): ~1sec.
- get_range_slices with native thrift bindings and small buffer size (1024): 
- get_range_slices with native thrift bindings and large buffer size (40960): 

I don't know why!!

P.S.: cassandra 0.6.3.

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