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  1. JDK
  2. JDK-4425695

Updating jar files crashes running programs


    • Type: Enhancement
    • Status: Open
    • Priority: P4
    • Resolution: Unresolved
    • Affects Version/s: solaris, javadb_10.0, 2.0, 1.3.0, 1.4.1, 1.4.1_01, 5.0, 5.0u1, 6, 6u16
    • Fix Version/s: None
    • Component/s: core-libs
    • Subcomponent:
    • CPU:
      generic, x86, sparc
    • OS:
      generic, linux, linux_redhat_9.0, solaris, solaris_9, solaris_nevada, solaris_10, windows_2000


      Name: boT120536 Date: 03/14/2001

      java version "1.3.0"
      Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0)
      Java HotSpot(TM) Client VM (build 1.3.0, mixed mode)

      Occasionnally, when updating a jar file while a java program uses it, said jave program throws
      spurious ClassNotFound errors. This is somewhat surprising, as similar problems don't occur
      when for instance updating a shared library (.so file) while programs use it.

      The problem occurs both on Windows and on Linux

      The reason why it doesn't happen for C libraries is because these are mmapped in PRIVATE
      mode into the program's address space, and hence the program sees a snapshot of their state how
      the library was when first started. It can thus continue its work undisturbed even through updates.

      Would it be possible to implement a similar scheme for access to .jar? For platforms where mmap
      is not supported, such as Windows, the jar could be read entirely in memory upon first use.
      (Review ID: 118787)


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              • Assignee:
                sherman Xueming Shen
                bonealsunw Bret O'neal (Inactive)
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                • Created: