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  1. JDK
  2. JDK-8247980

Exclusive execution of java/util/stream tests slows down tier1

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        Following up on why tier1 exhibits low paralellism when run on modern heavy-threaded desktop. On my TR 3970X, jdk:tier1 takes about 400 seconds, and there is a significantly large phase during which CPU load drops significantly.

        One of the reasons is JDK-8058204 that put java/util/stream tests to run in exclusive mode. Dropping java/util/stream from there improves the test times significantly (and CPU loads now make sense too):

        diff -r 216c6baa0564 test/jdk/TEST.ROOT
        --- a/test/jdk/TEST.ROOT Sat Jun 20 15:11:19 2020 +0800
        +++ b/test/jdk/TEST.ROOT Mon Jun 22 11:24:26 2020 +0200
        @@ -27,5 +27,5 @@
         sun/tools/jstatd sun/tools/jcmd sun/tools/jhsdb sun/tools/jhsdb/heapconfig \
         sun/tools/jinfo sun/tools/jmap sun/tools/jps sun/tools/jstack sun/tools/jstat \
        -com/sun/tools/attach sun/security/mscapi java/util/stream java/util/Arrays/largeMemory \
        +com/sun/tools/attach sun/security/mscapi java/util/Arrays/largeMemory \
         java/util/BitSet/stream javax/rmi
         
        $ time CONF=linux-x86_64-server-release make images run-test TEST=java/util/stream/

        # before: ~17x parallelism; mostly due to parallel javac compiles
        real 4m23.668s
        user 75m47.699s
        sys 2m50.316s

        # after: ~43x parallelism, limited by test tails
        real 1m32.027s
        user 61m59.474s
        sys 3m20.213s

        In other words, we are losing roughly 180s out of 400s jdk:tier1 for this, about 45% of the test time. This is way beyond the overhead JDK-8058204 envisioned originally ("I doubt it would increase the overall test run time, perhaps by 1% to 3%."). Observe:

        $ time CONF=linux-x86_64-server-release make images run-test TEST=jdk:tier1

        # before: ~25x parallelism
        real 6m37.627s
        user 158m32.437s
        sys 8m12.700s

        # after: ~44x parallelism
        real 3m43.018s
        user 159m47.390s
        sys 8m56.156s

        This makes jdk:tier1 almost 1.8x faster! fastdebug has roughly the same relative speedup.

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                Assignee:
                shade Aleksey Shipilev
                Reporter:
                shade Aleksey Shipilev
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