JDK-7018302 : newly added assert related to size of constantPoolOop causes secondary assertions or crashes
  • Type: Bug
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: hs21
  • Priority: P3
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2011-02-09
  • Updated: 2011-03-07
  • Resolved: 2011-03-07
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JDK 7 Other
7Fixed hs21Fixed
Related Reports
Relates :  
JDK-6912621 - iCMS: Error: assert(_markBitMap.isMarked(addr + 1),"Missing Printezis bit?")
Description
Nightly testing is running into secondary assertions or crashes as a reult of a newly-added
assert in 6912621 during cosntant pool creation. This needs to be investigated to root cause,
with the assertion suitably corrected, or at least temporarily weakened or removed until root
cause and fix are found.

The assertions occur with all collectors and across a range of platforms and tests, but the
following is representative of the essential failure modes:-

http://sqeweb.sfbay.sun.com/nfs/results/vm/gtee/JDK7/NIGHTLY/VM/2011-02-08/GC_Baseline-Xinc/new_unknown_failures.html
Comments
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/183658a2d0b3
11-02-2011
SUGGESTED FIX The following hides all use of the naked oop, using a handle uniformly throughout the method:- --- old/src/share/vm/oops/constantPoolKlass.cpp Wed Feb 9 17:10:12 2011 +++ new/src/share/vm/oops/constantPoolKlass.cpp Wed Feb 9 17:10:11 2011 @@ -55,32 +55,35 @@ constantPoolOop constantPoolKlass::allocate(int length, bool is_conc_safe, TRAPS) { int size = constantPoolOopDesc::object_size(length); KlassHandle klass (THREAD, as_klassOop()); - constantPoolOop c = - (constantPoolOop)CollectedHeap::permanent_obj_allocate(klass, size, CHECK_NULL); + assert(klass()->is_oop(), "Can't be null, else handlizing of c below won't work"); + constantPoolHandle pool; + { + constantPoolOop c = + (constantPoolOop)CollectedHeap::permanent_obj_allocate(klass, size, CHECK_NULL); + assert(c->klass_or_null() != NULL, "Handlizing below won't work"); + pool = constantPoolHandle(THREAD, c); + } - c->set_length(length); - c->set_tags(NULL); - c->set_cache(NULL); - c->set_operands(NULL); - c->set_pool_holder(NULL); - c->set_flags(0); + pool->set_length(length); + pool->set_tags(NULL); + pool->set_cache(NULL); + pool->set_operands(NULL); + pool->set_pool_holder(NULL); + pool->set_flags(0); // only set to non-zero if constant pool is merged by RedefineClasses - c->set_orig_length(0); + pool->set_orig_length(0); // if constant pool may change during RedefineClasses, it is created // unsafe for GC concurrent processing. - c->set_is_conc_safe(is_conc_safe); + pool->set_is_conc_safe(is_conc_safe); // all fields are initialized; needed for GC // Note: because we may be in this "conc_unsafe" state when allocating // t_oop below, which may in turn cause a GC, it is imperative that our // size be correct, consistent and henceforth stable, at this stage. - assert(c->is_parsable(), "Else size() below is unreliable"); - DEBUG_ONLY(int sz = c->size();) + assert(pool->is_oop() && pool->is_parsable(), "Else size() below is unreliable"); + assert(size == pool->size(), "size() is wrong"); // initialize tag array - // Note: cannot introduce constant pool handle before since it is not - // completely initialized (no class) -> would cause assertion failure - constantPoolHandle pool (THREAD, c); typeArrayOop t_oop = oopFactory::new_permanent_byteArray(length, CHECK_NULL); typeArrayHandle tags (THREAD, t_oop); for (int index = 0; index < length; index++) { @@ -89,7 +92,7 @@ pool->set_tags(tags()); // Check that our size was stable at its old value. - assert(sz == c->size(), "size() changed"); + assert(size == pool->size(), "size() changed"); return pool(); }
10-02-2011
SUGGESTED FIX diff -r c5a923563727 src/share/vm/oops/constantPoolKlass.cpp --- a/src/share/vm/oops/constantPoolKlass.cpp Mon Feb 07 22:19:57 2011 -0800 +++ b/src/share/vm/oops/constantPoolKlass.cpp Wed Feb 09 14:35:07 2011 -0800 @@ -89,7diff -r c5a923563727 src/share/vm/oops/constantPoolKlass.cpp --- a/src/share/vm/oops/constantPoolKlass.cpp Mon Feb 07 22:19:57 2011 -0800 +++ b/src/share/vm/oops/constantPoolKlass.cpp Wed Feb 09 15:31:21 2011 -0800 @@ -74,8 +74,8 @@ // Note: because we may be in this "conc_unsafe" state when allocating // t_oop below, which may in turn cause a GC, it is imperative that our // size be correct, consistent and henceforth stable, at this stage. - assert(c->is_parsable(), "Else size() below is unreliable"); - DEBUG_ONLY(int sz = c->size();) + assert(c->is_oop() && c->is_parsable(), "Else size() below is unreliable"); + assert(size == c->size(), "size() is wrong"); // initialize tag array // Note: cannot introduce constant pool handle before since it is not @@ -89,7 +89,7 @@ pool->set_tags(tags()); // Check that our size was stable at its old value. - assert(sz == c->size(), "size() changed"); + assert(size == pool->size(), "size() changed"); return pool(); }
09-02-2011
EVALUATION Use of a naked/unhandled oop. Fix by using handle instead.
09-02-2011