[Bug java/21703] New: hang when rapidly calling String.intern()

[Bug java/21703] New: hang when rapidly calling String.intern()

[debian-gcc at lists dot debian dot org]

[ forwarded from http://bugs.debian.org/275547 ]

falk@juist:/tmp% cat Test.java
class Test {
    public static void main(String[] argv) {
        for (char i = '\u0001'; i <= '\uffff'; i++) {
            char[] ca = { i };
            System.out.println("Interning "+((int)i)+"th String");
            (new String(ca)).intern();
        }
    }
}
falk@juist:/tmp% gcj-3.4 -o Test --main=Test Test.java  && ./Test 
[...]
Interning 16380th String
Interning 16381th String
Interning 16382th String
Interning 16383th String
Interning 16384th String
[hangs infintely]

See also some analysis at the URL above. Also present in 3.3.

-- 
           Summary: hang when rapidly calling String.intern()
           Product: gcc
           Version: 3.4.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: java
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: debian-gcc at lists dot debian dot org
                CC: gcc-bugs at gcc dot gnu dot org,java-prs at gcc dot gnu
                    dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703

[Bug libgcj/21703] hang when rapidly calling String.intern()

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|java                        |libgcj


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703

[Bug libgcj/21703] hang when rapidly calling String.intern()

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-21 20:14 -------
Confirmed, looks like the intern hash table becomes full.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-05-21 20:14:33
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703

[Bug libgcj/21703] hang when rapidly calling String.intern()

[tromey at gcc dot gnu dot org]

------- Additional Comments From tromey at gcc dot gnu dot org  2005-05-21 23:48 -------
Testing a patch.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |tromey at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703

[Bug libgcj/21703] hang when rapidly calling String.intern()

[tromey at gcc dot gnu dot org]

------- Additional Comments From tromey at gcc dot gnu dot org  2005-05-21 23:56 -------
In the upstream PR, a real deadlock is mentioned.
The backtrace shows the finalizer thread blocking.
Probably what is happening is that one thread is
spinning while looking for an empty slot in the string
hash table, and then the GC tries to finalize one of
these strings.  The String finalizer tries to acquire
the lock already held by the thread looking for an
empty slot, resulting in deadlock.

This is just a theory, I would need at least backtraces
of all the threads to be sure.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703

[Bug libgcj/21703] hang when rapidly calling String.intern()

[tromey at gcc dot gnu dot org]

------- Additional Comments From tromey at gcc dot gnu dot org  2005-05-22 00:37 -------
One more note -- the test case will loop infinitely
even when the intern() bug has been fixed, since every
'char' value is <= \uffff


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703

[Bug libgcj/21703] hang when rapidly calling String.intern()

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-05-22 01:04 -------
Subject: Bug 21703

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-4_0-branch
Changes by:	tromey@gcc.gnu.org	2005-05-22 01:04:47

Modified files:
	libjava        : ChangeLog 
	libjava/java/lang: natString.cc 
	libjava/java/lang/ref: natReference.cc 

Log message:
	PR libgcj/21703:
	* java/lang/ref/natReference.cc (find_slot): Handle case where
	table has no NULL entries.
	* java/lang/natString.cc (_Jv_StringFindSlot): Handle case where
	table has no NULL entries.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.3391.2.74&r2=1.3391.2.75
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/java/lang/natString.cc.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.36&r2=1.36.12.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/java/lang/ref/natReference.cc.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.6&r2=1.6.72.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703

[Bug libgcj/21703] hang when rapidly calling String.intern()

[tromey at gcc dot gnu dot org]

------- Additional Comments From tromey at gcc dot gnu dot org  2005-05-22 01:06 -------
I've checked in a patch on the 4.0 branch.
I will put it on the trunk when it emerges from its current
slushy state; I am leaving the PR open until then.
I'm not planning to put this on the 3.4 branch, but if someone
is motivated I think they are free to do so.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.0.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703

[Bug libgcj/21703] hang when rapidly calling String.intern()

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-05-25 15:24 -------
Subject: Bug 21703

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	tromey@gcc.gnu.org	2005-05-25 15:23:57

Modified files:
	libjava        : ChangeLog 
	libjava/java/lang: natString.cc 
	libjava/java/lang/ref: natReference.cc 

Log message:
	PR libgcj/21703:
	* java/lang/ref/natReference.cc (find_slot): Handle case where
	table has no NULL entries.
	* java/lang/natString.cc (_Jv_StringFindSlot): Handle case where
	table has no NULL entries.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/ChangeLog.diff?cvsroot=gcc&r1=1.3631&r2=1.3632
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/java/lang/natString.cc.diff?cvsroot=gcc&r1=1.37&r2=1.38
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/java/lang/ref/natReference.cc.diff?cvsroot=gcc&r1=1.6&r2=1.7



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703

[Bug libgcj/21703] hang when rapidly calling String.intern()

[tromey at gcc dot gnu dot org]

------- Additional Comments From tromey at gcc dot gnu dot org  2005-05-25 15:24 -------
Fix checked in.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21703