#1723: [bug] linked lists result in segfaults
----------------------+-----------------------------------------------------
Reporter: pmichaud | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: none | Version: 2.6.0
Severity: medium | Keywords:
Lang: | Patch:
Platform: |
----------------------+-----------------------------------------------------
Creating a linked list of moderate size ultimately leads to a segfault
during GC.
The following program simply creates a linked list of nodes. On my
system, I get a segfault after about 96K nodes:
{{{
pmich...@plum:~/parrot/trunk$ cat list2.pir
.sub 'main' :main
.local pmc iterclass, intclass
iterclass = newclass ['RangeIter']
addattribute iterclass, '$!value'
addattribute iterclass, '$!nextIter'
intclass = subclass ['Integer'], 'Int'
.local pmc head, next
head = new iterclass
$P0 = new intclass
setattribute head, '$!value', $P0
next = head
loop:
($I0, next) = next.'reify'()
$I1 = $I0 % 5000
if $I1 goto loop
say $I0
goto loop
.end
.namespace ['RangeIter']
.sub 'reify' :method
.local pmc value, nextiter
value = getattribute self, '$!value'
nextiter = new ['RangeIter']
setattribute self, '$!nextIter', nextiter
$P0 = add value, 1.0
setattribute nextiter, '$!value', $P0
.return ($P0, nextiter)
.end
pmich...@plum:~/parrot/trunk$ ./parrot list2.pir
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
55000
60000
65000
70000
75000
80000
85000
90000
95000
Segmentation fault
pmich...@plum:~/parrot/trunk$
}}}
gdb shows that the segfault occurs in gc mark:
{{{
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7a5d7e5 in Parrot_gc_mark_PMC_alive_fun (interp=0x60a080,
obj=0x3418e80) at src/gc/api.c:166
}}}
Some Rakudo users have reported segfaults on lists with less than 10,000
nodes.
Pm
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/1723>
Parrot <https://trac.parrot.org/parrot/>
Parrot Development
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