RFR(XS): [TEST] add test to verify EnableTrace works

[Liu, Xin]

Hi, David, 
Thank you for reviewing it. 

If you are using OracleJDK, it won't have any output. OracleJDK doesn't suffer from crash. I guess It suppress events unconditionally. 
For JDK8u, "-XX:+EnableTracing -version" will dump some events.  It won't crash if it has this patch http://hg.openjdk.java.net/jdk8u/jdk8u-dev/hotspot/rev/80ee2541504e
The attachment is the output. 

Output of jtreg
###
# Running suite single for openJDK
# Results are available in build/brazil-open-single-tests
###
Directory "build/JTwork" not found: creating
Passed: runtime/EnableTracing/TestEnableTracing.java
Test results: passed: 1
Report written to /local/home/xxinliu/ws-openjdk8/build/OpenJDK8CompatibilityTests/OpenJDK8CompatibilityTests-1.0/RHEL5_64/DEV.STD.PTHREAD/build/brazil-open-single-tests/html/report.html
Results written to /local/home/xxinliu/ws-openjdk8/build/OpenJDK8CompatibilityTests/OpenJDK8CompatibilityTests-1.0/RHEL5_64/DEV.STD.PTHREAD/build/JTwork

Thanks,
--lx


On 9/2/18, 10:01 PM, "David Holmes" <david.holmes at oracle.com> wrote:

    Hi,
    
    On 25/08/2018 2:35 AM, Liu, Xin wrote:
    > Hi, hotspot-Runtime Developers,
    > 
    > Could you review this small tests?
    > It adds a new test to verify +EnableTracing works for jdk8u.
    
    I don't see any output produced with just "-XX:+EnableTracing -version". ??
    
      > 
    /java/re/jdk/8u172/promoted/latest/binaries/linux-amd64/fastdebug/bin/java 
    -XX:+EnableTracing -version
    java version "1.8.0_172-fastdebug"
    Java(TM) SE Runtime Environment (build 1.8.0_172-fastdebug-b35)
    Java HotSpot(TM) 64-Bit Server VM (build 25.172-b35-fastdebug, mixed mode)
    
    Thanks,
    David
    
    > BUG:  https://bugs.openjdk.java.net/browse/JDK-8209863
    > WEBREV: http://cr.openjdk.java.net/~phh/8209863/webrev.00/
    > 
    > Thanks,
    > -lx
    >