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  1. JDK
  2. JDK-8150460

(linux|bsd|aix)_close.c: file descriptor table may become large or may not work at all

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 9
    • Fix Version/s: 9
    • Component/s: core-libs
    • Labels:
      None
    • Subcomponent:
    • Resolved In Build:
      b116
    • OS:
      linux, os_x, aix

      Description

      In linux_close.c - and similarily in bsd_close.c and aix_close.c - an array (fdTable) is used to keep an information record and a mutex per opened file descriptor. This array gets allocated at the start of the process.

      In order to guess on the size of the table, getrlimit(RLIMIT_NO_FILE) is used.

      There are some problems with this approach:

      1) There is no handling for an infinite limit. Depending on what the numerical value is for RLIM_INFINITY, allocation of the file descriptor table may fail at this point (RLIM_INFINITY=-1) or be very small (RLIM_INFINITY=0). This may lead to file descriptors not covered by the whole wakeup mechanism implemented in this file, and hence to hanging threads.

      2) For large - but not infinite - values of RLIMIT_NO_FILE, the memory usage is excessive. On Linux x64, each entry in the table is ~ 50Bytes; for a limit of 1000000, this eats up 50MB. Most of this memory is usually never used.

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              • Assignee:
                stuefe Thomas Stuefe
                Reporter:
                stuefe Thomas Stuefe
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                Dates

                • Created:
                  Updated:
                  Resolved: