Slow File Serving on Windows 2003

If you are experiencing slower than expected file download times, and you are using Windows 2003 (which we do not recommend as a server platform) then try one of the following remedies:

• ensure that the cache settings for the DefaultServlet in webdefault.xml are set correctly for your environment. By default, the max size of any one file that Jetty will attempt to cache is around 10Mb, so if you are serving larger files, you should increase this value, and possibly the values of the max number of cached files and the max size of the cache as a whole. The default cache settings in webdefault.xml are:

  <init-param> <param-name>maxCacheSize</param-name> <param-value>256000000</param-value> </init-param> <init-param> <param-name>maxCachedFileSize</param-name> <param-value>10000000</param-value> </init-param> <init-param> <param-name>maxCachedFiles</param-name> <param-value>1000</param-value> </init-param>

• try modifying the size of the response content buffer. By default, this is set to 24k, but can be modified on the SelectChannelConnector:

  <New class="org.mortbay.jetty.nio.SelectChannelConnector"> ... <Set name="responseBufferSize">1024</Set> </New>

  Our test results show - counter-intuitively - that a smaller buffer size may lead to faster download, with the optimum at 512 bytes :

  Measured Speed	Buffer Size
  4498.14 kb/s	16k
  6312.14 kb/s	8k
  6386.04 kb/s	4k
  7654.37 kb/s	2k
  9436.37 kb/s	1k
  10198.95 kb/s	512b
  9043.14 kb/s	256

• try using the blocking SocketConnector instead of the SelectChannelConnector, but be aware that this will not scale if you are also handling comet traffic.