On Fri, 2014-01-17 at 16:28 +0000, Boxer, Aaron wrote:
> I made a simple test: I wrote a few lines of Java using File channel and
> transferTo(...) method to read files from my DVD and write to the hard drive.
> With this simple test, the transferTo(...) method gets about 4 MB /S
> transfer rate to disk.
>
> Then, I put some timing code into the LengthDelimitedEncoder.transfer(...)
> method, and ran my application, which copies files from DVD
> to a socket. And the transferTo(...) from file to socket was getting about
> 0.7 MB /s . This is a 6 X degradation in performance.
> And, if you recall, if the files are already in the OS file cache, I get
> about 100 MB/S, so the socket is not slowing me down.
>
> I have done a little more testing: transferTo from DVD to local socket gets
> 3-4 MB/S transfer rate.
> I tried using a thread pool, and performance degrades (not surprisingly) as
> thread count rises from 1.
>
> Since DVD seeks are very slow, multiple threads trying to read at the same
> time will kill performance.
>
> But, I am not sure this is the issue here, because I have set
>
> connManager.setMaxTotal(1);
> connManager.setDefaultMaxPerRoute(1);
>
>
> So, there should only be one thread doing the transfer (is this true?)
>
Actually HttpAsyncClient uses multiple i/o dispatch threads, one per CPU core.
I suppose even with a cap of 1 total connection multiple threads might end up
trying to access the same physical device.
You can force HttpAsyncClient to use only one i/o dispatch thread by using a
custom IOReactorConfig
Thanks, Oleg. Here is my reactor config:
IOReactorConfig ioReactorConfig = IOReactorConfig.custom()
.setIoThreadCount(1)
.setConnectTimeout(30000)
.setSoTimeout(30000)
.setTcpNoDelay(true)
.build();
And the problem is still there with a thread count of 1.
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