Classpath in Jar manifest

Discussion in 'Java' started by Mike Schilling, Nov 28, 2010.

  1. We use Maven to build our product, which results in a few dozen jar files.
    Each contains a classpath entry in its manifest, which is an option you can
    set in the maven jar packager. This isn't of much use except in unusual
    circumstances (e.g. running java -jar from the command line), but you'd
    expect it to be harmless enough.

    Except that it isn't. We got a report from a customer that it slows down
    compilations to which these jars are inputs, and that turns out to be quite
    true. Turning that option off reduces a clean build from about 30 minutes
    to under 10. Does anyone have any idea what's going on here?
    Mike Schilling, Nov 28, 2010
    #1
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  2. Mike Schilling

    Roedy Green Guest

    On Sat, 27 Nov 2010 23:50:12 -0800, "Mike Schilling"
    <> wrote, quoted or indirectly quoted
    someone who said :

    >Except that it isn't. We got a report from a customer that it slows down
    >compilations to which these jars are inputs, and that turns out to be quite
    >true. Turning that option off reduces a clean build from about 30 minutes
    >to under 10. Does anyone have any idea what's going on here?


    Under some circumstances jar indexes are cached in ram as HashMaps.
    Other times they are linearly scanned on disk. I gather for some
    reason caching has been turned off. Sorry I don't know if it is even
    possible to control this during compile or jar build. You might
    experiment by where you place the jars.

    --
    Roedy Green Canadian Mind Products
    http://mindprod.com

    In programming, and documenting programs, keep vocabulary consistent and precisely defined! Variation in vocabulary to relieve the tedium is for novels.
    Roedy Green, Dec 2, 2010
    #2
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