8010309 : PlatformLogger: isLoggable performance / waste due to HashMap<Integer, Level (original) (raw)

Mandy Chung mandy.chung at oracle.com
Thu Mar 28 14:49:17 UTC 2013

Hi Peter, Laurent,

Thanks for the performance run. I'll push the changeset once I check the test result.

On 3/28/2013 2:52 AM, Peter Levart wrote:

...just a nit! In the test: private static void checkPlatformLoggerLevelMapping(Level level) { // map the given level to PlatformLogger.Level of the same name and value PlatformLogger.Level platformLevel = PlatformLogger.Level.valueOf(level.getName()); if (platformLevel == null || platformLevel.intValue() != level.intValue()) { throw new RuntimeException("Mismatched level: " + level + " PlatformLogger.Level" + platformLevel); } The Level.valueOf(String) is guaranteed to not return null.

That's right. Will fix it.

Laurent Bourges wrote:

Maybe you should introduce an explicit variable to make it more obvious: boolean initialize = false; // lazy initialization

I'll check the comments and see how I can make it clearer. I think it is. I don't think the variable helps (perhaps add a comment next to 'false').

Do you plan to apply the fix on JDK7 updates ?

I don't have any issue backporting this to jdk7u. I'll get back to you on this one how to coordinate on this once this is baked in jdk8 repo first.

Thanks Mandy

Regards, Peter I have retained the part in webrev.08 that only defines loggerProxy and javaLoggerProxy. I don't think the new defaultLoggerProxy variable is needed. I prefer to use Class.forName to force load JavaLoggerProxy class to make very explicit that we don't want the class be initialized. JavaLoggerProxy. calls LoggingProxy.parseLevel unconditionally that will throw an AssertionError if java.util.logging is not available. If JavaLoggerProxy class is initialized, j.u.logging should be present and I want to catch error if otherwise. Also Class.forName will load its superclass LoggerProxy. As for the PlatformLogger.Level enums, having the members to be defined in ascending order is fragile. It'd be more reliable to specify the value in the constructor so that it can be used as the isLoggable comparsion in the same way as in the Level implementation. I am running the jdk core regression tests on all platforms and should have the result by tomorrow. On 3/27/2013 9:44 AM, Peter Levart wrote: Hi Mandy, Laurent,

It turns out that the API change (change of type for level parameter int -> enum Level) is entirely source-compatible. The tip of JDK8 (tl repo) builds without a problem. So no-one is currently using PlatformLogger.getLevel() method and assigning it to a variable or such...

Great thanks. That is what I expect too. Here's the webrev for this change: http://dl.dropbox.com/u/101777488/jdk8-tl/PlatformLogger/webrev.enumapi.01/index.html Besides doing the replacement of type and renaming and removing of the unneeded stuff, I also did some re-arrangements: - introduced a common abstract superclass for both types of LoggerProxys (DefaultLoggerProxy, JavaLoggerProxy), since JavaLoggerProxy does not need the fields of DefaultLoggerProxy and now both concrete subclasses can be declared final (makes JIT even more happy). Also the abstract LoggerProxy could host some common logic (see below about formatting)... That's a good idea. - DefaultLoggerProxy's levelValue/effectiveLevel were given names just the opposite of their meaning. I aligned them with terminology used in j.u.l.Logger and renamed levelValue to plain level. Swapping these 2 variables makes sense. - introduced private method DefaultLoggerProxy.deriveEffectiveLevel(level) that currently just returns defaultLevel (INFO) when given null. Ok. I think with a little more effort, it could be possible to emulate the behaviour of j.u.l.Logger which inherits from 1st parent logger that has non-null level assigned. Of course with all the caching and invalidation... The only way to change the level to a non-default one is via the logging configuration and enable logging. That's why there is no need for DefaultLoggerProxy to inherit level from its parent logger. Also there is no parent logger hierarchy maintained in DefaultLoggerProxy. - instead of static final DefaultLoggerProxy.defaultStream I created a private static method outputStream() that returns System.err. To accomodate for the situation when System.err is changed dynamically. Ok. - fixed the JavaLoggerProxy.isEnabled() method. Original code was: 532 boolean isEnabled() { 533 Object level = LoggingSupport.getLevel(javaLogger); 534 return level == null || level.equals(levelObjects.get(OFF)) == false; 535 } If 'level' is null then it can be that 1st parent that has a non-nul level is "OFF". I think that in such situation all the children that don't override the level should be disabled too. The following does exactly that: 597 boolean isEnabled() { 598 return LoggingSupport.isLoggable(javaLogger, Level.OFF.javaLevel); 599 } That is right. Good catch. That's all for 1st rev. Besides the effective level inheritance, the following method in JavaLoggerProxy also caught my eye: void doLog(Level level, String msg, Object... params) { if (!isLoggable(level)) { return; } // only pass String objects to the j.u.l.Logger which may // be created by untrusted code int len = (params != null) ? params.length : 0; Object[] sparams = new String[len]; for (int i = 0; i < len; i++) { sparams [i] = String.valueOf(params[i]); } LoggingSupport.log(javaLogger, level.javaLevel, msg, sparams); } I think this could be improved if the DefaultLoggerProxy.formatMessage() is used instead of turning each parameter into a String. The method could be moved up to abstract LoggerProxy and used in both implementations so that common formatting is applied regardless of back-end used. Let's do this in a separate clean up as it's better to keep 8010309 focus on performance improvement (although we have mixed this bag with some renaming). The benchmarks still show stable performance: Great. Hope we will wrap up tomorrow. thanks for the contribution. Mandy

Regards, Peter On 03/26/2013 10:37 PM, Mandy Chung wrote: Hi Peter, http://dl.dropbox.com/u/101777488/jdk8-tl/PlatformLogger/webrev.08/index.html I'm glad that you observe similar performance improvement without the need of method handles. I reviewed this version and realize that the map from j.u.l.Level object to LevelEnum can be removed entirely. sun.util.logging.PlatformLogger is an internal API that should only be used by JDK. The static final int fields representing the level value can be changed to be static final LevelEnum type instead. I checked the JDK code that uses PlatformLogger and no code will be impacted by the change of the type of these static fields. So it removes the need to map from an integer value to LevelEnum. Mapping from a j.u.l.Level to LevelEnum is trivial - the name of the LevelEnum is the same as j.u.l.Level (e.g. LevelEnum.FINEST and Level.FINEST), you can call LoggingSupport.getLevelName(javaLevel) to find its name and LevelEnum.valueOf(levelName) returns the LevelEnum instance. However, this would require more changes - basically the methods taking "int level" as a parameter would be modified to take LevelEnum and getLevel() would return LevelEnum too. I think it's worth doing this cleanup to get rid of the unnecessary conversion from int -> enum -> j.u.l.Level and vice versa. I also recommend to rename LevelEnum to Level which is an inner class of PlatformLogger. What do you think of this alternative to get rid of the map? Some other comments of your patch: - it renames the class JavaLogger to JavaLoggerProxy and the variable from logger to loggerProxy. I'm fine with that. - L162: JavaLoggerProxy.init() to force load of the class which leads to separating the initialization of LevelEnum.javaLevel in a new JavaLevel class. The JavaLevel utility methods are not needed if we change the static final fields to LevelEnum. Have you tried: Class.forName("sun.util.logging.PlatformLogger.JavaLoggerProxy", false, PlatformLogger.getClassLoader()); would this give you the same performance improvement? If so, you can keep the static initialization in the JavaLoggerProxy class. Thanks for expanding the PlatformLoggerTest to cover additional test cases. It's good that you compare the value of the PlatformLogger static final fields with j.u.l.Level.intValue(). You now can use the API to compare the LevelEnum with Level rather than reflection. Perhaps you can add the getName() and intValue() methods in LevelEnum class (just a thought). Mandy

On 3/25/13 9:31 AM, Peter Levart wrote: Well, Laurent, Mandy, It turns out that the dispatch speed-up (or lack of slow-down to be precise) is possible without MethodHandles too. Maybe some VM guru could shed some light on this, but the following is currently the fastest variant: http://dl.dropbox.com/u/101777488/jdk8-tl/PlatformLogger/webrev.08/index.html What I did is a simple "if" deciding between two call-sites, making sure that each is only dispatching to single class. This only works, if both classes (LoggerProxy and JavaLoggerProxy) are loaded in advance, before 1st invocation on any of them is made (might be that using MethodHandles forced initialization of both classes beforehand and hence the speed-up). If I don't load JavaLoggerProxy before warming-up with LoggerProxy, then when j.u.logging is enabled, speed drops for a factor of almost 4 and never catches up even after very long time. This pre-loading also helps for a normal single call site dispatch that dispatches to two distinct classes, but the speed 1st drops when the class changes, and only catches-up after several billions of iterations (30s tight loop on i7). Now, because JavaLoggerProxy is initialized early, I had to move the initialization of j.u.logging.Level objects and mappings to a separate class "JavaLevel". Here are the benchmark results for this last iteration...

More information about the core-libs-dev mailing list