RFR: 8150103: Convert TraceClassPaths to Unified Logging

Max Ockner max.ockner at oracle.com
Fri Feb 19 20:11:12 UTC 2016

I have responded to these suggestions.
New webrev: http://cr.openjdk.java.net/~mockner/classpath.05/

  - ClassLoader::trace_class_path() no longer takes a stream argument. 
Because the body of trace_class_path is guarded by the classpath tag 
(formerly TraceClassPaths), the output should always go to 
  - SharedPathMiscInfo::trace_class_path() has been removed since it is 
now redundant. Its only purpose was to call trace_class_path on tty. 
ClassLoader::trace_class_path is now called in its place.
  - print_path() no longer takes a stream argument. It now prints to 
  - Accessing LogHandle(classpath)::info_stream() was causing issues 
with the nonexistant current thread in arguments.cpp, so the single 
logging statement in arguments.cpp was moved to classLoader.cpp.


On 2/18/2016 7:28 AM, David Holmes wrote:
> Hi Max,
> This conversion is not straight-forward, and not complete.
> On 18/02/2016 8:19 AM, Max Ockner wrote:
>> Hello everyone,
>> Please review this conversion of TraceClassPaths to UL.
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8150103
>> Webrev: http://cr.openjdk.java.net/~mockner/classpath.03/
> src/share/vm/classfile/classLoader.cpp
> This call:
>  477     trace_class_path(tty, "[Bootstrap loader class path=", 
> sys_class_path);
> shouldn't be passing tty but should be the outputstream for the "info" 
> log.
> ---
> src/share/vm/runtime/arguments.cpp
> Same here:
>   if (!PrintSharedArchiveAndExit) {
>     ClassLoader::trace_class_path(tty, "[classpath: ", 
> _java_class_path->value());
>   }
> ---
> src/share/vm/classfile/sharedPathsMiscInfo.hpp
> You didn't modify this file but you need to change the 2-arg 
> trace_class_path() to not use the tty.
> This conversion seems a bit problematic to me. trace_class_path was 
> enabled/disabled via TraceClassPaths, but it could write to different 
> output streams. With UL you would always want it to write to the 
> single UL related stream - which means the API really needs to change, 
> and the extraction of the correct log stream can then be internalized. 
> But there may be some compatibility issues in doing that for the 
> place(s) where it may not be writing to tty.
> I don't see a simple conversion process here. I think all 
> trace_class_path calls should be the two-arg forms with no stream arg, 
> and that version then inlines the current 3-arg version but always 
> writes to the info log stream. But then you also have print_path which 
> wraps a call to trace_class_path ... to be honest I don't see what 
> purpose print_path serves, it just seems to be complicating things.
> David
> ----
>> Summary:  TraceClassPaths flag has been reimplemented using the
>> classpath tag with Info level.  TraceClassPaths has been added to the
>> logging alias table.
>> There is some related output that was never guarded by "if
>> (TraceClassPaths)", so it has not been included in this conversion.
>> Testing: jtreg runtime tests. Added basic test case at
>> test/runtime/logging/ClassPathTest.java
>> Thanks,
>> Max

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