Hi Mandy, On Thu, Sep 17, 2009 at 9:54 PM, Mandy Chung <mandy.ch...@sun.com> wrote: > Oleg, Anthony, > > You all raise good questions and we shall focus on the problem we want to > fix by 6879044 and 6882376. It's important to separate the discussion for > this fix vs the startup performance improvement. I hope below clears up > some confusion and this review request is for addressing problem described > in (1). > > (1) The problem is to decouple the dependency on logging from some JRE > components. > > FYI. The jigsaw project page [1] provides links to the good background why > we're doing that. Mark gave a very good overview and demo of Project jigsaw > at JavaOne General Technical Session[2]. > > Logging is one candidate module if the libraries are broken up into a set of > fine grained modules. The fix for 6882376 provides the internal support > for JRE implementation to eliminate their dependency on logging. Alan and > Naoto reviewed the fix. > > As for the AWT/2D/Swing changes, > 6879044: Eliminate the dependency on logging from the AWT/2D/Swing > classes, > > When the libraries are broken into modules, are you saying that the client > module should require the logging module to exist? On the other hand, as > Alan explained, why would a user need to have a logging module installed to > run a simple client application?
Ok, so this fix is only about modules. But why AWT should not depend on logging module? The qiestion is: how many application we want to run doesn't use logging& Because if an application uses logging there is no reasons for AWT to not use it. Please note that even if logging is turned off, the application still needs logging package/module. So, though end-user doesn't need logging output she may need logging module to run the application. So, it is really important to understand what number of application will get advantage of suggested changes. Second question is: how big logging module is going to be? How big the benefit for end-user will be? I'm asking so many question mainly because the changes you suggested create rather unnatural code (we can not use standard logging machinery any more), so such changes should be well-justified. With best regards, Oleg. > Artem and Dmitri reviewed the fix. If you have another proposal of > decoupling the dependency, I would be interested too. > > (2) Startup performance improvement > > The suggested change does not have a signifcant startup performance as > expected (as I mentioned in the bug report). It does load fewer classes > (~16 classes) which isn't bad. My apology if I confuse you when we mixed it > in this review request. > > I have done some performance analysis [3] [4] to determine what opportunity > the jigsaw module system could implement and the estimate of the startup > time improvement we could possibly get. Decoupling dependency is an > important step to modularize the JDK while the startup gain may not be > materialized until the module system is in place. > > (3) AWT loggers > > The AWT loggers are for debugging purpose. I understand the advantage of > fine-grained loggers to have a fine-grained control of the debugging output. > It's a tradeoff between performance (time and memory) and such debugging > ability. I would argue that this fine-grained debugging ability is nice to > have but isn't necessary to be available in the production environment. You > should consider some way to enable such debuggability but disabled by > default to minimize the performance overhead such as lazily creating these > logger. sun.font only enables logging when -Dsun.java2d.debugfonts=true > system property is set to true. This should be revisited - see 6880089 [5]. > > (4) Performance and design of java.util.logging > > I totally agree with that the performance and design of j.u.logging should > be improved. If you have any idea and solution, your contribution would be > appreciated. In fact, I would hope that we could have something like DTrace > [6] that tracing code can be added in the implementation but no overhead is > paid if the probes are not enabled [7]. > > Thanks > Mandy > > [1] http://openjdk.java.net/projects/jigsaw/ > [2] > http://java.sun.com/javaone/2009/playlist.jsp?pid=24494811001&autoStart=on > [3] http://mail.openjdk.java.net/pipermail/jigsaw-dev/2009-July/000181.html > [4] > http://cr.openjdk.java.net/~mchung/startup_measurement/perfdata.summary.b64 > [5] http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6880089 > [6] http://www.sun.com/bigadmin/content/dtrace/index.jsp > [7] https://btrace.dev.java.net/ >
