February 2012 - core-libs-dev

hg: jdk8/tl/jdk: 7079093: TEST_BUG: java/lang/instrument/ManifestTest.sh fails with cygwin
by staffan.larsen＠oracle.com 24 Feb '12

24 Feb '12

Changeset: 4893a89b4916 Author: sla Date: 2012-02-24 20:09 +0100 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/4893a89b4916 7079093: TEST_BUG: java/lang/instrument/ManifestTest.sh fails with cygwin Summary: Work around problems in some cygwin installations Reviewed-by: alanb, sspitsyn ! test/ProblemList.txt ! test/java/lang/instrument/ManifestTest.sh

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hg: jdk8/tl/jdk: 7073626: RmiBootstrapTest.sh and RmiSslBootstrapTest.sh fail under Cygwin
by staffan.larsen＠oracle.com 24 Feb '12

24 Feb '12

Changeset: 585f2c72d042 Author: sla Date: 2012-02-24 20:02 +0100 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/585f2c72d042 7073626: RmiBootstrapTest.sh and RmiSslBootstrapTest.sh fail under Cygwin Summary: Detect and handle cygwin correctly Reviewed-by: alanb, sspitsyn ! test/ProblemList.txt ! test/sun/management/jmxremote/bootstrap/GeneratePropertyPassword.sh

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hg: jdk8/tl/langtools: 7137836: tidy up Names.java
by jonathan.gibbons＠oracle.com 24 Feb '12

24 Feb '12

Changeset: e6b5c3aff85c Author: jjg Date: 2012-02-24 10:40 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/langtools/rev/e6b5c3aff85c 7137836: tidy up Names.java Reviewed-by: mcimadamore ! src/share/classes/com/sun/tools/javac/util/Names.java

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RFR: 6988220: java.lang.ObjectName use of String.intern() causes major performance issues at scale
by Frederic Parain 24 Feb '12

24 Feb '12

This a simple fix to solve CR 6988220: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6988220 The use of String.intern() in the ObjectName class prevents the class the scale well when more than 20K ObjectNames are managed. The fix simply removes the use of String.intern(), and uses regular String instead. The Object.equals() method is modified too to make a regular String comparison. The complexity of this method now depends on the length of the ObjectName's canonical name, and is not impacted any more by the number of ObjectName instances being handled. The Webrev: http://cr.openjdk.java.net/~fparain/6988220/webrev.00/ I've tested this fix with the jdk_lang and jdk_management test suites. Thanks, Fred -- Frederic Parain - Oracle Grenoble Engineering Center - France Phone: +33 4 76 18 81 17 Email: Frederic.Parain(a)oracle.com

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hg: jdk8/tl/jdk: 7144488: Infinite recursion for some equals tests in Collections
by sean.coffey＠oracle.com 24 Feb '12

24 Feb '12

Changeset: 0a350fb8b174 Author: coffeys Date: 2012-02-24 09:17 +0000 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/0a350fb8b174 7144488: Infinite recursion for some equals tests in Collections Reviewed-by: alanb, dholmes, mduigou ! src/share/classes/java/util/Collections.java + test/java/util/Collections/EqualsTest.java

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hg: jdk8/tl/jdk: 7133138: Improve io performance around timezone lookups
by sean.coffey＠oracle.com 24 Feb '12

24 Feb '12

Changeset: a589a8dbde79 Author: coffeys Date: 2012-02-24 09:10 +0000 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/a589a8dbde79 7133138: Improve io performance around timezone lookups Reviewed-by: okutsu ! make/tools/src/build/tools/javazic/Mappings.java ! src/share/classes/sun/util/calendar/ZoneInfo.java ! src/share/classes/sun/util/calendar/ZoneInfoFile.java

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Re: RFR: 6988220: java.lang.ObjectName use of String.intern() causes major performance issues at scale
by Frederic Parain 24 Feb '12

24 Feb '12

Making String.intern() more scalable doesn't seem to be a solution for short (or medium?) time frame. Even if the computation cost of ObjectName.equals() is increased by this fix, there's no performance measurement in favor or against this change. I've looked for benchmarks stressing the ObjectName class, but I haven't found one yet. Using java.util "Set" or "Map" introduces new issues, like the memory footprint and new synchronizations to protect consistency of the collection. The Ops-Center team is stuck with this scalability issue for two years now. They have identified the problem in JDK6 and we're not able to provide them with a solution for JDK7 or JDK8. David, I agree that I have no data about the impact on other use-cases, but I know that the use of String.intern() cannot be easily workaround. We can remove the use of String.intern() and if the performance of the new ObjectName.equals() method really becomes a performance bottleneck for other use-cases, them we can re-work this method to improve its performance. But I'd prefer not starting complex optimizations on a method without having real indication that it causes real performance issues. Fred On 2/23/12 11:23 PM, Keith McGuigan wrote: > > Making String.intern() more scalable has been on our list of > things-to-do for a long, long time. But, it's not trivial. Simply > increasing the size of the hashtable is no good because we'd be upping > our footprint unconditionally, so really we want a growing hashtable > which is a bit more effort (though not impossible, of course, it just > hasn't bubbled up to the top of the priority list). > > Another problem with using 'intern()' is that when you intern a string > you're placing it into the permgen, and space there is at a premium. (no > perm gen project will hopefully fix this soon). > > If you really want to use == instead of "equals()", you can use a > java.util "set" or "map" data structure and stash all of your strings in > there. Then you'll have canonicalized references that == will work upon, > and you won't run into the intern() scalability (or concurrency) issues. > > -- > - Keith > > > On 2/23/2012 4:53 PM, David Holmes wrote: >> Hi Fred, >> >> java.lang.ObjectName? :) Need to fix that. >> >> So often we intern strings precisely so that equals() can use == to >> improve performance. >> >> It seems to me that this is a case of "fixing" something for one >> use-case without knowing what the impact will be on other use-cases! >> >> Is there perhaps a solution that makes String.intern more scalable? >> >> David >> ----- >> >> On 24/02/2012 1:36 AM, Frederic Parain wrote: >>> This a simple fix to solve CR 6988220: >>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6988220 >>> >>> The use of String.intern() in the ObjectName class prevents >>> the class the scale well when more than 20K ObjectNames are >>> managed. The fix simply removes the use of String.intern(), >>> and uses regular String instead. The Object.equals() method >>> is modified too to make a regular String comparison. The >>> complexity of this method now depends on the length of >>> the ObjectName's canonical name, and is not impacted any >>> more by the number of ObjectName instances being handled. >>> >>> The Webrev: >>> http://cr.openjdk.java.net/~fparain/6988220/webrev.00/ >>> >>> I've tested this fix with the jdk_lang and jdk_management >>> test suites. >>> >>> Thanks, >>> >>> Fred >>> -- Frederic Parain - Oracle Grenoble Engineering Center - France Phone: +33 4 76 18 81 17 Email: Frederic.Parain(a)oracle.com

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RFR: 7133138 Improve io performance around timezone lookups
by Seán Coffey 24 Feb '12

24 Feb '12

I've worked with Masayoshi on this issue. Hoping to push to JDK8 and backport to 7u and a jdk6 once baked for a while. Some windows boxes were showing performance issues when attempting to iterate through all available timezones available in the JRE. Changes made here should reduce the amount of file stat calls made on jre/lib/zi/* files. Tweaks are made to the alias table also to reduce number of aliases that require lookup. All TZ regression tests run without issue. I've seen a 20-30% speed up on iteration of timezones on windows as a result. Unix doesn't appear to suffer as badly from such a file IO hit. http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7133138 http://cr.openjdk.java.net/~coffeys/webrev.7133138/ regards, Sean.

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RFR : 7144488 StackOverflowError occurres on list via Collections.synchronizedList(List)
by Seán Coffey 23 Feb '12

23 Feb '12

Bug recently reported. We enter infinite recursion on a boundary case for Collections.synchronizedList.remove(..) Fix is a simple equals check in class method before delegating the call. bug : http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7144488 webrev : http://cr.openjdk.java.net/~coffeys/webrev.7144488/ regards, Sean.

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hg: jdk8/tl/langtools: 7148025: javac should not warn about InterrupttedException on the declaration of AutoCloseable itself
by joe.darcy＠oracle.com 23 Feb '12

23 Feb '12

Changeset: 3ad851a7e884 Author: darcy Date: 2012-02-23 09:53 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/langtools/rev/3ad851a7e884 7148025: javac should not warn about InterrupttedException on the declaration of AutoCloseable itself Reviewed-by: mcimadamore ! src/share/classes/com/sun/tools/javac/comp/Attr.java

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