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  1. JDK
  2. JDK-8027455

Improve symbol table scan times during gc pauses

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    • gc
    • b03

        The symbol table stores references to symbols. Each of these symbols is reference counted; if the reference count of a symbol reaches zero, it can be removed.

        Currently, the symbol table is cleaned up during various GC pauses, as it provides a convenient opportunity where no random modification by other threads can occur.

        However, particularly because this cleanup process is serial, it takes a long time. In particular across a large range of FMW applications (see attached log file), it takes 50% of remark pause time, which is way too high.

        Symbol table scan/scrubbing pause time must be improved; there are several options for this:

        - parallelize this task
        - incrementally scrub the symbol table (i.e. only parts at once) given e.g. a time allowance
        - maybe move it or parts of it, e.g. just finding the scrub-able entries, to a concurrent task

          1. remark_pause_time.log.bz2
            121 kB

              tschatzl Thomas Schatzl
              tschatzl Thomas Schatzl
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