RFC: JWarmup precompile java hot methods at application startup

[yumin qi]

Hi, all

  Please check following link for second version:
  http://cr.openjdk.java.net/~minqi/8220692/webrev-02/

  The changes are based on Tobias' and Alan's comments.
  1)  Add OS checking to enable JWarmUp run with Linux only.
  2) created new module for jwarmup (jdk.jwarmup)
       make JWamUp instance singleton. Calling its functions has to go with
the only instance.

  I moved JWarmUp.registerNatives to jvm.cpp instead, before it is a
separate file src/java.base/share/native/libjava/JWarmUp.c. Now the file
removed.
 One problem confused me is, with a new module jdk.jwarmup and all others
kept as before, it is unable to find the native of JWarmUp.registerNatives
though its native entry is still in libjava.so like before. (certainly
changed calling convention according to new package name)
  Now the registerNatives is found when it looks up for native entry in
lookupNative.cpp. I thought the class JWarmUp will be loaded by boot loader
like Unsafe or WhiteBox, but I was wrong, it is loaded by app class loader
so logic for obtaining its native entry put in both cases, boot loader and
non boot loaders.

   3) changed test cases to run with new jdk.jwarmup module. All test cases
run on Linux only.

   Tests: passed all tests locally.
    Submit build failed in local due to a compilation error:
/home//ws/submit/submit/build/linux-x86_64-server-slowdebug/support/gensrc/jdk.internal.vm.compiler/org/graalvm/compiler/replacements/arraycopy/PluginFactory_ArrayCopySnippets.java:35:
error: cannot find symbol
        jdk.internal.vm.compiler.word.LocationIdentity result =
org.graalvm.compiler.replacements.arraycopy.ArrayCopySnippets.getArrayLocation(arg0);

                                             ^
     (I will double check that, it is not related to this change).

   Please give your comments.

Thanks
Yumin





On Thu, Mar 14, 2019 at 10:59 PM yumin qi <yumin.qi at gmail.com> wrote:

> Please review the patch for implementing JEP 8203832:
> (*https://bugs.openjdk.java.net/browse/JDK-8203832 <https://bugs.openjdk.java.net/browse/JDK-8203832>)*
>
> Bug: *https://bugs.openjdk.java.net/browse/JDK-8220692 <https://bugs.openjdk.java.net/browse/JDK-8220692>*
> Webrev: http://cr.openjdk.java.net/~minqi/8220692/webrev-01/ <http://cr.openjdk.java.net/~minqi/8203832/webrev-01/>
>
> Summary: This patch implements the first version of JIT warmup to solve the java application peak time CPU contest between JIT compiler threads and regular application java threads. The CPU contest is avoided by pre-run to collect comilation data and precompile the hot java methods during application startup based on the pre-run collected data.
>
> The main flags (-XX:) used to control are:
> CompilationWarmUpRecording: used for collecting compilation data. Result stored in a file set by flag CompilationWarmUpLogfile.
> CompilationWarmUp: use collected data to precompile the methods recorded in above file.
> CompilationWarmUpExclude: configure a file which contains the names to be excluded for precompile.
> CompilationWarmUpRecordTime: control the warmup recording time.
> CompilationWarmUpDeoptTime: time (from start) to deoptimize precomiled methods.
>
> In this version, the profiled method data is not used at precomilation, it will be addressed in followed bug fix. After the first version integrated, will file bug for it. Also, it does not work with CDS since the data added to ConstantPool data structure. It also will be addressed in another separate bug followed.
>
> Test: Submitted to submit repo and passed all tests.
> Newly added test suites:  test/hotspot/jtreg/jwarmup include test cases for most of the use cases and issues.
>
> Thanks
> Yumin
>
>