Remove exception from sun.rmi.runtime.Log#getSource()

[Roger Riggs]

Hi Philippe,

I'll be happy to sponsor the fix.

Mandy's suggestion makes sense to me, please update the patch.

I filed https://bugs.openjdk.java.net/browse/JDK-8230058 to track the 
change.

Regards, Roger


On 8/22/19 1:56 PM, Mandy Chung wrote:
> Hi Philippe,
>
> This is a good use of StackWalker.   getSource can simply return
> StackFrame and avoid the creation of String[].
>
> Stuart will give you better guidance related to RMI testing.
>
> I see that test/jdk/sun/rmi/runtime/Log has a few RMI logging tests.
> RMI tests are in tier3.  You can run jdk_rmi test group to verify
> this patch.
>
> I notice that pre-1.4 RMI logging support.  I wonder if this is
> time to remove it.
>
> Mandy
>
> On 8/22/19 7:21 AM, Philippe Marschall wrote:
>> Hello
>>
>> First time contributor here.
>>
>> We have exception tracing enabled in production and see thousands of
>> exceptions in sun.rmi.runtime.Log#getSource() to get the caller class.
>> In my option this should use StackWalker introduced in Java 9. I could
>> find no corresponding bug in JBS.
>>
>> I created a and uploaded webrev here [1] and also added the patch inline
>> below. As for the implementation I created a custom StackWalker to be
>> able to pass in the estimated number of frames that we traverse. For
>> variable naming conventions I tried to stick with other StackWalker
>> users I could find in the JDK. The stream formatting tries to follow the
>> LVTI style guidelines.
>>
>> I have not written a test as the method is private. I ran the tier1
>> tests and they passed.
>>
>> I have signed the OCA.
>>
>> What are the next steps?
>>
>>
>> --- old/src/java.rmi/share/classes/sun/rmi/runtime/Log.java 2019-08-21
>> 14:16:47.381544386 +0200
>> +++ new/src/java.rmi/share/classes/sun/rmi/runtime/Log.java 2019-08-21
>> 14:16:47.249545585 +0200
>> @@ -30,6 +30,7 @@
>>  import java.io.OutputStream;
>>  import java.rmi.server.LogStream;
>>  import java.security.PrivilegedAction;
>> +import java.util.Set;
>>  import java.util.logging.Handler;
>>  import java.util.logging.SimpleFormatter;
>>  import java.util.logging.Level;
>> @@ -62,6 +63,8 @@
>>      public static final Level BRIEF = Level.FINE;
>>      public static final Level VERBOSE = Level.FINER;
>>
>> +    private static final StackWalker WALKER =
>> StackWalker.getInstance(Set.of(), 4);
>> +
>>      /* selects log implementation */
>>      private static final LogFactory logFactory;
>>      static {
>> @@ -444,10 +447,10 @@
>>       * Obtain class and method names of code calling a log method.
>>       */
>>      private static String[] getSource() {
>> -        StackTraceElement[] trace = (new Exception()).getStackTrace();
>> -        return new String[] {
>> -            trace[3].getClassName(),
>> -            trace[3].getMethodName()
>> -        };
>> +        return WALKER.walk(s -> s
>> +                                 .skip(3)
>> +                                 .map(f -> new String[]
>> {f.getClassName(), f.getMethodName()})
>> +                                 .findFirst()
>> +                                 .get());
>>      }
>>  }
>>
>>  [1]
>> https://github.com/marschall/webrevs/raw/master/Log-getSource/webrev.zip
>>
>> Cheers
>> Philippe Marschall
>>
>