February 2014 - core-libs-dev

RFR(S): 8034087: XML parser may overwrite element content if that content falls onto the border of an entity scanner buffer
by Volker Simonis 11 Feb '14

11 Feb '14

Hi, after opening this bug yesterday for an issue found by my colleague Steffen Schreiber we realized that this is actually a duplicate of "8027359: XML parser returns incorrect parsing results" (https://bugs.openjdk.java.net/browse/JDK-8027359) While there's no need now to submit a patch anymore, we'd nevertheless like to contribute at least our test case for this issue: http://cr.openjdk.java.net/~simonis/webrevs/8034087/ The webrev is against jdk9-client but we'd like to also downport this test to jdk7 and jdk8 to track that the fix for 8027359 will be correctly downported to these releases as well. I will sponsor this change if somebody would be so kind to review it. Thank you and best regards, Volker

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hg: jdk8/tl/jdk: 14 new changesets
by lana.steuck＠oracle.com 11 Feb '14

11 Feb '14

Changeset: 75cf17ceb6d1 Author: katleman Date: 2014-01-22 12:54 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/75cf17ceb6d1 Added tag jdk8-b125 for changeset ae303640bc1c ! .hgtags Changeset: 95410515ba5f Author: katleman Date: 2014-01-22 14:08 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/95410515ba5f Merge ! .hgtags Changeset: 91bce40d0347 Author: alexsch Date: 2014-01-23 20:36 +0400 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/91bce40d0347 8032063: javax.swing.plaf.metal.MetalFileChooserUI$FilterComboBoxModel extends non-standard API Reviewed-by: pchelko, serb ! src/macosx/classes/com/apple/laf/AquaFileChooserUI.java ! src/share/classes/com/sun/java/swing/plaf/gtk/GTKFileChooserUI.java ! src/share/classes/com/sun/java/swing/plaf/motif/MotifFileChooserUI.java ! src/share/classes/com/sun/java/swing/plaf/windows/WindowsFileChooserUI.java ! src/share/classes/javax/swing/plaf/metal/MetalFileChooserUI.java - src/share/classes/sun/swing/AbstractFilterComboBoxModel.java ! src/share/classes/sun/swing/plaf/synth/SynthFileChooserUIImpl.java Changeset: 6935e7a3a7c9 Author: amurillo Date: 2014-01-23 14:46 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/6935e7a3a7c9 Merge Changeset: a9088d517f2f Author: amurillo Date: 2014-01-23 14:47 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/a9088d517f2f Merge Changeset: a635c394328c Author: katleman Date: 2014-01-24 15:08 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/a635c394328c Added tag jdk8-b126 for changeset a9088d517f2f ! .hgtags Changeset: fbf251b8ef8a Author: lana Date: 2014-01-29 11:11 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/fbf251b8ef8a Merge Changeset: f777d83e0433 Author: katleman Date: 2014-01-30 12:17 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/f777d83e0433 Added tag jdk8-b127 for changeset fbf251b8ef8a ! .hgtags Changeset: f644211c59fd Author: lana Date: 2014-01-31 13:47 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/f644211c59fd Merge Changeset: 3c9473004f38 Author: katleman Date: 2014-02-01 18:21 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/3c9473004f38 Added tag jdk8-b128 for changeset f644211c59fd ! .hgtags Changeset: ab6e7bb8ff9f Author: pchelko Date: 2014-01-22 16:15 +0400 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/ab6e7bb8ff9f 7155984: Security problems in regression test java/awt/PrintJob/Security/SecurityDialogTest.java Reviewed-by: anthony, serb ! src/macosx/classes/apple/laf/JRSUIUtils.java Changeset: eef10feca8ca Author: lana Date: 2014-02-06 13:28 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/eef10feca8ca Merge Changeset: 80568a19aab7 Author: lana Date: 2014-02-06 13:29 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/80568a19aab7 Merge Changeset: 43386cc9a017 Author: katleman Date: 2014-02-06 17:35 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jdk/rev/43386cc9a017 Added tag jdk8-b129 for changeset 80568a19aab7 ! .hgtags

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hg: jdk8/tl/nashorn: 8 new changesets
by lana.steuck＠oracle.com 11 Feb '14

11 Feb '14

Changeset: d336209a0e45 Author: katleman Date: 2014-01-22 12:54 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/nashorn/rev/d336209a0e45 Added tag jdk8-b125 for changeset 7346abe2ea03 ! .hgtags Changeset: 095263db862d Author: katleman Date: 2014-01-22 14:00 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/nashorn/rev/095263db862d Merge ! .hgtags Changeset: e2522604c7c9 Author: katleman Date: 2014-01-24 15:08 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/nashorn/rev/e2522604c7c9 Added tag jdk8-b126 for changeset 095263db862d ! .hgtags Changeset: fdfbb745caf0 Author: lana Date: 2014-01-29 11:12 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/nashorn/rev/fdfbb745caf0 Merge Changeset: 7dfde83426d1 Author: katleman Date: 2014-01-30 12:17 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/nashorn/rev/7dfde83426d1 Added tag jdk8-b127 for changeset fdfbb745caf0 ! .hgtags Changeset: 73cbad0c5d28 Author: lana Date: 2014-01-31 13:47 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/nashorn/rev/73cbad0c5d28 Merge Changeset: 9cc3fd32fbab Author: katleman Date: 2014-02-01 18:21 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/nashorn/rev/9cc3fd32fbab Added tag jdk8-b128 for changeset 73cbad0c5d28 ! .hgtags Changeset: f87eba70e9ee Author: katleman Date: 2014-02-06 17:35 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/nashorn/rev/f87eba70e9ee Added tag jdk8-b129 for changeset 9cc3fd32fbab ! .hgtags

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hg: jdk8/tl/hotspot: 23 new changesets
by lana.steuck＠oracle.com 11 Feb '14

11 Feb '14

Changeset: 16e0c6c84a91 Author: amurillo Date: 2014-01-13 16:00 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/16e0c6c84a91 8031553: new hotspot build - hs25-b67 Reviewed-by: jcoomes ! make/hotspot_version Changeset: 12ad8db39f76 Author: roland Date: 2014-01-14 09:44 +0100 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/12ad8db39f76 8028764: dtrace/hotspot_jni/ALL/ALL001 crashes the vm on Solaris-amd64, SIGSEGV in MarkSweep::follow_stack()+0x8a Summary: C1 generates code to encode compressed oop into tmp register before runtime call for patching where GC may happen Reviewed-by: iveresov, twisti, kvn Contributed-by: mgerdin <mikael.gerdin(a)oracle.com> ! src/cpu/x86/vm/c1_LIRAssembler_x86.cpp Changeset: 8b81451dc7f7 Author: twisti Date: 2014-01-16 16:18 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/8b81451dc7f7 8022395: java.util.zip.ZipException: Not in GZIP format in JT_JDK/test/java/util/zip/GZIP tests Reviewed-by: kvn, iveresov ! src/cpu/x86/vm/c1_LIRGenerator_x86.cpp Changeset: 3585183c191a Author: amurillo Date: 2014-01-17 20:24 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/3585183c191a Merge Changeset: 5df2666e4573 Author: amurillo Date: 2014-01-17 20:24 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/5df2666e4573 Added tag hs25-b67 for changeset 3585183c191a ! .hgtags Changeset: 55ff9170e27d Author: katleman Date: 2014-01-22 12:53 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/55ff9170e27d Added tag jdk8-b125 for changeset df333ee12bba ! .hgtags Changeset: c8218f1072a0 Author: katleman Date: 2014-01-22 14:07 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/c8218f1072a0 Merge ! .hgtags Changeset: 9a11d5e679cf Author: katleman Date: 2014-01-24 15:07 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/9a11d5e679cf Added tag jdk8-b126 for changeset c8218f1072a0 ! .hgtags Changeset: c2106608358b Author: amurillo Date: 2014-01-17 20:30 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/c2106608358b 8032015: new hotspot build - hs25-b68 Reviewed-by: jcoomes ! make/hotspot_version Changeset: 709018897c81 Author: vlivanov Date: 2014-01-23 01:23 +0400 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/709018897c81 8031695: CHA ignores default methods during analysis leading to incorrect code generation Reviewed-by: jrose, acorn, hseigel, lfoltan ! src/share/vm/code/dependencies.cpp + test/compiler/inlining/DefaultAndConcreteMethodsCHA.java Changeset: f970454708b8 Author: iveresov Date: 2014-01-17 18:09 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/f970454708b8 8032207: C2: assert(VerifyOops || MachNode::size(ra_) <= (3+1)*4) failed: bad fixed size Summary: Fix the sizing of loadUS2L_immI16 and loadI2L_immI Reviewed-by: kvn, azeemj ! src/cpu/sparc/vm/sparc.ad + test/compiler/codegen/LoadWithMask.java Changeset: 984401824c5e Author: iveresov Date: 2014-01-21 20:05 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/984401824c5e 8031743: C2: loadI2L_immI broken for negative memory values Summary: Restrict loadI2L_imm optimizations to positive values of mask Reviewed-by: kvn, dlong ! src/cpu/sparc/vm/sparc.ad ! src/cpu/x86/vm/x86_32.ad ! src/cpu/x86/vm/x86_64.ad + test/compiler/codegen/LoadWithMask2.java Changeset: d45454002494 Author: amurillo Date: 2014-01-23 13:37 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/d45454002494 Merge Changeset: 2c564e329c87 Author: amurillo Date: 2014-01-23 13:37 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/2c564e329c87 Added tag hs25-b68 for changeset d45454002494 ! .hgtags Changeset: 58879cd9f8df Author: amurillo Date: 2014-01-28 09:51 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/58879cd9f8df Merge ! .hgtags Changeset: 7e412f95e310 Author: amurillo Date: 2014-01-23 13:53 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/7e412f95e310 8032608: new hotspot build - hs25-b69 Reviewed-by: jcoomes ! make/hotspot_version Changeset: 2185d483f5f8 Author: kvn Date: 2014-01-27 10:20 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/2185d483f5f8 8032566: Crash in JIT when running Scala compiler (and compiling Scala std lib) Summary: Switch off EliminateAutoBox flag by default in jdk8 release. Reviewed-by: iveresov ! src/share/vm/opto/c2_globals.hpp Changeset: 32f017489ba5 Author: amurillo Date: 2014-01-28 15:00 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/32f017489ba5 Merge Changeset: 1d8728efc05f Author: amurillo Date: 2014-01-28 15:00 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/1d8728efc05f Added tag hs25-b69 for changeset 32f017489ba5 ! .hgtags Changeset: 35038da7bb9d Author: lana Date: 2014-01-29 11:11 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/35038da7bb9d Merge Changeset: 874c0b4a946c Author: katleman Date: 2014-01-30 12:16 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/874c0b4a946c Added tag jdk8-b127 for changeset 35038da7bb9d ! .hgtags Changeset: cb39165c4a65 Author: katleman Date: 2014-02-01 18:21 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/cb39165c4a65 Added tag jdk8-b128 for changeset 874c0b4a946c ! .hgtags Changeset: 1dbaf664a611 Author: katleman Date: 2014-02-06 17:34 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/hotspot/rev/1dbaf664a611 Added tag jdk8-b129 for changeset cb39165c4a65 ! .hgtags

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hg: jdk8/tl/jaxp: 7 new changesets
by lana.steuck＠oracle.com 11 Feb '14

11 Feb '14

Changeset: 6a5af8a36aaf Author: katleman Date: 2014-01-22 12:53 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxp/rev/6a5af8a36aaf Added tag jdk8-b125 for changeset 83bb924238f8 ! .hgtags Changeset: 390cc275c04c Author: katleman Date: 2014-01-22 14:07 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxp/rev/390cc275c04c Merge ! .hgtags Changeset: 573c261a2025 Author: katleman Date: 2014-01-24 15:08 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxp/rev/573c261a2025 Added tag jdk8-b126 for changeset 390cc275c04c ! .hgtags Changeset: b68cdb63a70b Author: lana Date: 2014-01-29 11:11 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxp/rev/b68cdb63a70b Merge Changeset: b1839922f10c Author: katleman Date: 2014-01-30 12:16 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxp/rev/b1839922f10c Added tag jdk8-b127 for changeset b68cdb63a70b ! .hgtags Changeset: b7752cea7c81 Author: katleman Date: 2014-02-01 18:21 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxp/rev/b7752cea7c81 Added tag jdk8-b128 for changeset b1839922f10c ! .hgtags Changeset: 0cb0cd015218 Author: katleman Date: 2014-02-06 17:34 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxp/rev/0cb0cd015218 Added tag jdk8-b129 for changeset b7752cea7c81 ! .hgtags

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hg: jdk8/tl/langtools: 7 new changesets
by lana.steuck＠oracle.com 11 Feb '14

11 Feb '14

Changeset: 9a4dbfe11ed1 Author: katleman Date: 2014-01-22 12:54 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/langtools/rev/9a4dbfe11ed1 Added tag jdk8-b125 for changeset 436176151e85 ! .hgtags Changeset: ba24b6304362 Author: katleman Date: 2014-01-22 14:09 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/langtools/rev/ba24b6304362 Merge ! .hgtags Changeset: 305b97f4651b Author: katleman Date: 2014-01-24 15:08 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/langtools/rev/305b97f4651b Added tag jdk8-b126 for changeset ba24b6304362 ! .hgtags Changeset: bb69217ed812 Author: lana Date: 2014-01-29 11:12 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/langtools/rev/bb69217ed812 Merge Changeset: 09cdd3b493c0 Author: katleman Date: 2014-01-30 12:17 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/langtools/rev/09cdd3b493c0 Added tag jdk8-b127 for changeset bb69217ed812 ! .hgtags Changeset: 8fe7202d3c38 Author: katleman Date: 2014-02-01 18:21 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/langtools/rev/8fe7202d3c38 Added tag jdk8-b128 for changeset 09cdd3b493c0 ! .hgtags Changeset: 9d81ae1c417a Author: katleman Date: 2014-02-06 17:35 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/langtools/rev/9d81ae1c417a Added tag jdk8-b129 for changeset 8fe7202d3c38 ! .hgtags

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hg: jdk8/tl/jaxws: 7 new changesets
by lana.steuck＠oracle.com 11 Feb '14

11 Feb '14

Changeset: c0040f0b75e2 Author: katleman Date: 2014-01-22 12:53 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxws/rev/c0040f0b75e2 Added tag jdk8-b125 for changeset ef71ecbcd7bc ! .hgtags Changeset: 7193a007a159 Author: katleman Date: 2014-01-22 14:07 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxws/rev/7193a007a159 Merge ! .hgtags Changeset: 3f682f2ea376 Author: katleman Date: 2014-01-24 15:08 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxws/rev/3f682f2ea376 Added tag jdk8-b126 for changeset 7193a007a159 ! .hgtags Changeset: 8e46fe36e175 Author: lana Date: 2014-01-29 11:11 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxws/rev/8e46fe36e175 Merge Changeset: de172acc095b Author: katleman Date: 2014-01-30 12:16 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxws/rev/de172acc095b Added tag jdk8-b127 for changeset 8e46fe36e175 ! .hgtags Changeset: aabc90596123 Author: katleman Date: 2014-02-01 18:21 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxws/rev/aabc90596123 Added tag jdk8-b128 for changeset de172acc095b ! .hgtags Changeset: 4195c0956930 Author: katleman Date: 2014-02-06 17:35 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/jaxws/rev/4195c0956930 Added tag jdk8-b129 for changeset aabc90596123 ! .hgtags

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hg: jdk8/tl/corba: 7 new changesets
by lana.steuck＠oracle.com 11 Feb '14

11 Feb '14

Changeset: 18c4d03cf516 Author: katleman Date: 2014-01-22 12:53 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/corba/rev/18c4d03cf516 Added tag jdk8-b125 for changeset 7b45151c7a05 ! .hgtags Changeset: 8ceb68fd9e10 Author: katleman Date: 2014-01-22 14:06 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/corba/rev/8ceb68fd9e10 Merge ! .hgtags Changeset: cfa04e69b115 Author: katleman Date: 2014-01-24 15:07 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/corba/rev/cfa04e69b115 Added tag jdk8-b126 for changeset 8ceb68fd9e10 ! .hgtags Changeset: b8c71dae0557 Author: lana Date: 2014-01-29 11:11 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/corba/rev/b8c71dae0557 Merge Changeset: 113e7569b49b Author: katleman Date: 2014-01-30 12:16 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/corba/rev/113e7569b49b Added tag jdk8-b127 for changeset b8c71dae0557 ! .hgtags Changeset: 5c72d74c6805 Author: katleman Date: 2014-02-01 18:21 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/corba/rev/5c72d74c6805 Added tag jdk8-b128 for changeset 113e7569b49b ! .hgtags Changeset: eea0d7dfcbe2 Author: katleman Date: 2014-02-06 17:34 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/corba/rev/eea0d7dfcbe2 Added tag jdk8-b129 for changeset 5c72d74c6805 ! .hgtags

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hg: jdk8/tl: 8 new changesets
by lana.steuck＠oracle.com 11 Feb '14

11 Feb '14

Changeset: 950921234b10 Author: katleman Date: 2014-01-22 12:53 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/rev/950921234b10 Added tag jdk8-b125 for changeset 790bbd46b201 ! .hgtags Changeset: 1b5d578f93ef Author: katleman Date: 2014-01-22 14:06 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/rev/1b5d578f93ef Merge ! .hgtags Changeset: 9ccce5bf1b0e Author: katleman Date: 2014-01-24 04:45 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/rev/9ccce5bf1b0e Merge Changeset: 4f8fa4724c14 Author: katleman Date: 2014-01-24 15:07 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/rev/4f8fa4724c14 Added tag jdk8-b126 for changeset 9ccce5bf1b0e ! .hgtags Changeset: 2e2ffb9e4b69 Author: lana Date: 2014-01-29 11:11 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/rev/2e2ffb9e4b69 Merge Changeset: 101e42de4686 Author: katleman Date: 2014-01-30 12:16 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/rev/101e42de4686 Added tag jdk8-b127 for changeset 2e2ffb9e4b69 ! .hgtags Changeset: 1e5fe8654913 Author: katleman Date: 2014-02-01 18:21 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/rev/1e5fe8654913 Added tag jdk8-b128 for changeset 101e42de4686 ! .hgtags Changeset: 839546caab12 Author: katleman Date: 2014-02-06 17:34 -0800 URL: http://hg.openjdk.java.net/jdk8/tl/rev/839546caab12 Added tag jdk8-b129 for changeset 1e5fe8654913 ! .hgtags

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AtomicReference.compareAndSet allows multiple threads to succeed
by Peter Harvey 11 Feb '14

11 Feb '14

If multiple threads call AtomicReference.compareAndSet with the same pair of values, it appears that multiple threads may succeed. For example, if multiple threads call compareAndSet("Alpha", "Beta") then they may all succeed. Is this the correct behaviour? The documentation maybe should make this clear, as most developers and tutorials seem to assume that the compareAndSet methods of the Atomic classes guarantee that at most one thread will succeed. I've included full demonstration code at the very bottom of this email. In this demo, multiple threads are popping items from a stack and then pushing items back on to the stack. I discovered that it was possible for two threads to pop the same item from the stack, despite using compareAndSet to modify the head of the stack. Specifically, this code did not work as intended: AtomicReference<StackEntry> stack = new AtomicReference<StackEntry>(); ... // Pop an entry from the top of the queue StackEntry entry; while (true) { entry = stack.get(); if (entry == null) break; // Atomic, right? Only one thread can succeed... if (stack.compareAndSet(entry, entry.next)) break; } Peter. Full demo code below: -------------------------------------- public class AtomicReferenceTest { private static final class StackEntry { volatile Thread owner; volatile StackEntry next; } private static final AtomicReference<StackEntry> stack = new AtomicReference<StackEntry>(); private static class MyThread extends Thread { @Override public void run() { while (true) { /* * Pop an entry off the top of the stack. The only way to exit * this loop is to have found an empty stack, or to have * ATOMICALLY replaced the head of the stack with the next item * on the stack. In theory, no two threads should be able to * exit this loop with the SAME entry... */ StackEntry entry; while (true) { entry = stack.get(); if (entry == null) break; // Atomic, right? Only one thread can succeed... if (stack.compareAndSet(entry, entry.next)) break; } /* * If there was nothing on the stack, make a new entry. * Otherwise, just set the 'next' to null. This isn't required * but is good practice. */ if (entry == null) entry = new StackEntry(); else entry.next = null; /* * Check if the entry really was exclusively claimed. In theory, * no two threads should ever have a reference to the same * entry... */ Thread owner = entry.owner; if (owner != null) System.err.println("ALREADY CLAIMED BY " + owner); entry.owner = Thread.currentThread(); /* Push the entry back on to the queue. */ entry.owner = null; while (true) { entry.next = stack.get(); // Atomic, right? Only one thread can succeed... if (stack.compareAndSet(entry.next, entry)) break; } } } }; public static void main(String[] args) { Thread[] threads = new Thread[8]; for (int i = 0; i < threads.length; i++) threads[i] = new MyThread(); for (int i = 0; i < threads.length; i++) threads[i].start(); } } -- *Actenum Corporation* Peter Harvey | Cell: 780.729.8192 | harvey(a)actenum.com | www.actenum.com

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