JDK-5107263 : Worse performance of isSupported for JISAutoDetect (1.4.X)
  • Type: Bug
  • Component: core-libs
  • Sub-Component: java.nio.charsets
  • Affected Version: 1.4.2_05
  • Priority: P3
  • Status: Closed
  • Resolution: Fixed
  • OS: windows_xp
  • CPU: x86
  • Submitted: 2004-09-27
  • Updated: 2010-02-17
  • Resolved: 2005-09-02
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1.4.2_10 b02Fixed
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We have found worse performance of isSupported with "JISAutoDetect".

   1) Compile the attached test program
   2) Launch "java isSupportedTest1"
  We can see the result of execution(elapse) time as follows.


  This is done in 1.4.2_05.

   OS : Windows XP (SP, Japanese)
   JRE : 1.4.2_05
   Mem: 384 [MB]
   MPU : Pentium IV 1.4[GHz]


EVALUATION JISAutoDetect is not a supported charset in 1.4.2, whereas in 1.5 it is. If I modify the testcase and use an unsupported charset and run with 1.5, then it takes a longer time in 1.5 also. So the behavior is same in both 1.4.2 & 1.5 with respect to unsupported charsets. To avoid this performance bottleneck, we will have to backport support for JISAutoDetect. I will have to check if we can backport this. ###@###.### 2005-2-24 11:43:37 GMT As per the documentation JISAutoDetect is part of Extended Encoding Set, which is supported only by java.io and java.lang APIs and not by java.nio APIs. See http://java.sun.com/j2se/1.4.2/docs/guide/intl/encoding.doc.html Which means, JISAutoDetect is a valid encoding supported by Java but can not be accessed via the NIO API which the test case does. It can be closed as not a bug. ###@###.### 2005-04-18 12:37:34 GMT