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  1. JDK
  2. JDK-8027455

Improve symbol table scan times during gc pauses

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    • gc
    • b03

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      Description

        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

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            backported by

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8032233 Improve symbol table scan times during gc pauses

            • P3 - Major loss of function.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8033520 Improve symbol table scan times during gc pauses

            • P3 - Major loss of function.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8034539 Improve symbol table scan times during gc pauses

            • P3 - Major loss of function.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8045198 Improve symbol table scan times during gc pauses

            • P3 - Major loss of function.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8053203 Improve symbol table scan times during gc pauses

            • P3 - Major loss of function.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8028404 Improve symbol table scan times during gc pauses

            • P3 - Major loss of function.
            • Closed
            relates to

            Bug - A problem which impairs or prevents the functions of the product. JDK-8033443 Test8000311 fails after latest changes to parallelize string and symbol table unlink

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

            Enhancement - null JDK-8031472 Fine tune string/symbol table parallelization

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Open

            Enhancement - null JDK-8031473 Parallelize symbol table and string table unlink in non-G1 parallel collectors

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Open

            Enhancement - null JDK-8031565 Use serial/waiting time to perform independent tasks during young gc in G1

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Open

            Enhancement - null JDK-8027543 Turn off symbol table scan if not class unloading in G1 remark phase

            • P3 - Major loss of function.
            • Closed

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                tschatzl Thomas Schatzl
                tschatzl Thomas Schatzl
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                  Updated:
                  Resolved: