On Thu, 19 Sep 2024 07:08:56 GMT, Roberto Castañeda Lozano <rcastaned...@openjdk.org> wrote:
>> Hi all, >> >> Currently, the Unified Logging framework defaults to three decorators >> (uptime, level, tags) whenever the user does not specify otherwise through >> `-Xlog`. This can result in cumbersome input whenever a specific user that >> relies on a particular tag(s) has some predefined needs. For example, C2 >> developers rarely need decorations, and having to manually specify this >> every time results inconvenient. >> >> To address this, this PR enables the possibility of adding tag-specific >> default decorators to UL. These defaults are in no way overriding user input >> -- they will only act whenever `-Xlog` has no decorators supplied and there >> is a positive match with the pre-specified defaults. Such a match is based >> on the following: >> >> - Inclusion: if `-Xlog:jit+compilation` is provided, a default for `jit` may >> be applied. >> - Specificity: if, for the above line, there is a more specific default for >> `jit+compilation` the latter shall be applied. Upon equal specificity cases, >> both defaults will be applied. >> - Additionally, defaults may target a specific log level. >> >> Decorators are also associated with an output file, so an output device may >> only have one set of decorators. For this reason, if different >> `LogSelection`s trigger defaults, none is to be applied. >> >> In summary, these defaults may be seen as a "tailored" or "flavoured" >> version of the existing "uptime-level-tags" current defaults. >> >> Please consider this PR, and thanks! > > Nice proposal, Antón! This will make it possible to migrate lots of > debug/trace-level ad-hoc logging in the compiler code to the UL while > preserving its current format (e.g. time decorators are hardly needed when > examining the output of `-XX:+TraceLoopOpts`). > > Having said this, I find the following behavior unintuitive. If I run: > > > -Xlog:jit*=debug > > > I get the global default decorators, i.e. `uptime,level,tags`, which is what > I expected. But if I run: > > > java -Xlog:jit+compilation=debug,jit+inlining=debug,jit+thread=debug > > > I would expect to get the same decorators, but instead I get the default > decorators for `jit+inlining`, i.e. none. Is this intentional? > > In general, as a HotSpot developer the behavior I would find most natural is > to select the union of all decorators for all chosen tags (regardless of > whether the decorators for a tag have been chosen actively by the user, > specified as default for the tag, or "inherited" from the global default), as > in the first option (`-Xlog:jit*=debug`). @robcasloz Originally I had thought of these defaults "taking over" if there were no defaults for the rest, but I know what you mean and in a way the uptime-level-tags are some implicit defaults that should also be applied. Merging all default specification as suggested by @jdksjolen would automatically enable this behaviour ------------- PR Comment: https://git.openjdk.org/jdk/pull/20988#issuecomment-2370406970
