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Struts & Hibernate
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| | | performance problem with ServletOutputStream.write() | performance problem with ServletOutputStream.write() 2005-01-17 - By Jean-Christian Imbeault
Back
I previously asked the list about a performance problem I had while
reading files of disk and then streaming them to clients.
I didn't notice there was a 'problem' until I compare the time it takes
our application to stream the file to our users vs. the time it takes
out application server (acting a plain web server) to serve up the same
file. Streaming takes about 5x longer!
Many people suggested that I read and write the file from the
presentation layer servlet in order to save on objects, memory, etc ...
I did this and to my surprise I barely saw any improvements at all in
the speed at which the pdf file is streamed. I added lots of 'debugging'
code to find out where the bottleneck was and was shocked to see that
almost all the time spent (about 90%) is when I sent the file back to
the client by calling ServletOutputStream.write().
I'm pretty much out of ideas on how to 'fix' this since there really is
no other to send something to the client than to write() to the
OuputStream as far as I know.
The code basically boils down to:
read file off disk using BufferedInputStream
write file using ServletOutputStream.write()
That's it. Nothing else. I can't see any way to improve this code.
Can someone shed light on why streaming is so much slower at
transmitting files than a 'regular' web server?
Is there anything I can do to improve my situation?
Thanks!
Sample code and output from a test case is included below:
ServletOutputStream out = res.getOutputStream();
buff = new byte[fileLength];
startDate = new Date();
System.out.println("PERF: " + userIDForPDFPerformance
+ " :FiDServlet:doPost\t-BEGIN :" + startDate
+ " *** CASE 5 READ ***");
bis.read(buff, 0, buff.length);
endDate = new Date();
System.out.println("PERF: " + userIDForPDFPerformance
+ " :FiDServlet:doPost\t-END :" + endDate + " Time Diff:" +
(endDate.getTime() - startDate.getTime()) / 1000.0
+ " *** CASE 5 READ ***");
startDate = new Date();
System.out.println("PERF: " + userIDForPDFPerformance
+ " :FiDServlet:doPost\t-BEGIN :" + startDate
+ " *** CASE 5 WRITE ***");
out.write(buff, 0, buff.length);
endDate = new Date();
System.out.println("PERF: " + userIDForPDFPerformance
+ " :FiDServlet:doPost\t-END :" + endDate + " Time Diff:" +
(endDate.getTime() - startDate.getTime()) / 1000.0
+ " *** CASE 5 WRITE ***");
==SAMPLE OUTPUT==
PERF: -121*35*-3 :FiDServlet:doPost -BEGIN :Mon Jan 17 16:34:46 JST
2005 *** CASE 5 READ ***
PERF: -121*35*-3 :FiDServlet:doPost -END :Mon Jan 17 16:34:46 JST
2005 Time Diff:0.0050 *** CASE 5 READ ***
PERF: -121*35*-3 :FiDServlet:doPost -BEGIN :Mon Jan 17 16:34:46 JST
2005 *** CASE 5 WRITE ***
PERF: -121*35*-3 :FiDServlet:doPost -END :Mon Jan 17 16:34:53 JST
2005 Time Diff:6.739 *** CASE 5 WRITE ***
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