[issue24606] segfault caused by nested calls to map()

[Ned Deily]

Ned Deily added the comment:

Process 51270 launched: './python' (x86_64)
Process 51270 stopped
* thread #1: tid = 0x5c8677, 0x0001000c1af8 
python`_PyObject_Alloc(use_calloc=0, ctx=unavailable, nelem=unavailable, 
elsize=unavailable) + 24 at obmalloc.c:1170, queue = 'com.apple.main-thread', 
stop reason = EXC_BAD_ACCESS (code=2, address=0x7fff5eb8)
frame #0: 0x0001000c1af8 python`_PyObject_Alloc(use_calloc=0, 
ctx=unavailable, nelem=unavailable, elsize=unavailable) + 24 at 
obmalloc.c:1170
   1167
   1168 static void *
   1169 _PyObject_Alloc(int use_calloc, void *ctx, size_t nelem, size_t elsize)
- 1170 {
   1171 size_t nbytes;
   1172 block *bp;
   1173 poolp pool;
(lldb) bt
* thread #1: tid = 0x5c8677, 0x0001000c1af8 
python`_PyObject_Alloc(use_calloc=0, ctx=unavailable, nelem=unavailable, 
elsize=unavailable) + 24 at obmalloc.c:1170, queue = 'com.apple.main-thread', 
stop reason = EXC_BAD_ACCESS (code=2, address=0x7fff5eb8)
  * frame #0: 0x0001000c1af8 python`_PyObject_Alloc(use_calloc=0, 
ctx=unavailable, nelem=unavailable, elsize=unavailable) + 24 at 
obmalloc.c:1170
frame #1: 0x0001000c0ec8 
python`_PyObject_Malloc(ctx=0x, nbytes=112) + 40 at 
obmalloc.c:1386
frame #2: 0x0001000c03e9 python`_PyMem_DebugAlloc(use_calloc=0, 
ctx=0x000100390898, nbytes=80) + 153 at obmalloc.c:1838
frame #3: 0x0001000be981 
python`_PyMem_DebugMalloc(ctx=0x000100390898, nbytes=80) + 33 at 
obmalloc.c:1861
frame #4: 0x0001000bf3c1 python`PyObject_Malloc(size=80) + 65 at 
obmalloc.c:386
frame #5: 0x00010028c87e python`_PyObject_GC_Alloc(use_calloc=0, 
basicsize=56) + 110 at gcmodule.c:1696
frame #6: 0x00010028c809 python`_PyObject_GC_Malloc(basicsize=56) + 25 
at gcmodule.c:1718
frame #7: 0x00010028ca6d 
python`_PyObject_GC_NewVar(tp=0x000100393990, nitems=2) + 109 at 
gcmodule.c:1747
frame #8: 0x0001000d6c82 python`PyTuple_New(size=2) + 338 at 
tupleobject.c:104
frame #9: 0x0001001d7e26 python`map_next(lz=0x00010cebbae8) + 38 at 
bltinmodule.c:1162
frame #10: 0x00010001072c python`PyIter_Next(iter=0x00010cebbae8) + 
44 at abstract.c:2760
frame #11: 0x0001001d7e71 python`map_next(lz=0x00010ce8) + 113 
at bltinmodule.c:1167
frame #12: 0x00010001072c python`PyIter_Next(iter=0x00010ce8) + 
44 at abstract.c:2760
frame #13: 0x0001001d7e71 python`map_next(lz=0x00010cebbc88) + 113 
at bltinmodule.c:1167
frame #14: 0x00010001072c python`PyIter_Next(iter=0x00010cebbc88) + 
44 at abstract.c:2760
frame #15: 0x0001001d7e71 python`map_next(lz=0x00010cebbd58) + 113 
at bltinmodule.c:1167
frame #16: 0x00010001072c python`PyIter_Next(iter=0x00010cebbd58) + 
44 at abstract.c:2760
frame #17: 0x0001001d7e71 python`map_next(lz=0x00010cebbe28) + 113 
at bltinmodule.c:1167
frame #18: 0x00010001072c python`PyIter_Next(iter=0x00010cebbe28) + 
44 at abstract.c:2760
frame #19: 0x0001001d7e71 python`map_next(lz=0x00010cebbef8) + 113 
at bltinmodule.c:1167
frame #20: 0x00010001072c python`PyIter_Next(iter=0x00010cebbef8) + 
44 at abstract.c:2760
frame #21: 0x0001001d7e71 python`map_next(lz=0x00010cebd058) + 113 
at bltinmodule.c:1167
frame #22: 0x00010001072c python`PyIter_Next(iter=0x00010cebd058) + 
44 at abstract.c:2760
frame #23: 0x0001001d7e71 python`map_next(lz=0x00010cebd128) + 113 
at bltinmodule.c:1167
frame #24: 0x00010001072c python`PyIter_Next(iter=0x00010cebd128) + 
44 at abstract.c:2760
[...]

--
nosy: +ned.deily

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[issue24606] segfault caused by nested calls to map()

[Ned Deily]

Changes by Ned Deily n...@acm.org:


--
nosy:  -ned.deily

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[issue24606] segfault caused by nested calls to map()

[Mark Lawrence]

Mark Lawrence added the comment:

FTR I can reproduce this on Windows 8.1 with 3.4.3 and 3.3.5 but not 2.7.10 or 
2.6.6.

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nosy: +BreamoreBoy

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[issue24606] segfault caused by nested calls to map()

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

This looks as a duplicate of issue14010.

--
nosy: +serhiy.storchaka
resolution:  - duplicate
stage:  - resolved
status: open - closed
superseder:  - deeply nested filter segfaults

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[issue24606] segfault caused by nested calls to map()

[David Lukeš]

New submission from David Lukeš:

The following program makes Python 3.4.3 crash with a segmentation fault:

```
#!/usr/bin/env python3

import operator

N = 50
l = [0]

for i in range(N):
l = map(operator.add, l, [1])

print(list(l))
```

I suppose the problem is that there are too many nested lazy calls to map, 
which cause a segfault when evaluated. I've played with N and surprisingly, the 
threshold to cause the crash varied slightly (between 130900 and 131000 on my 
machine).

I know that a list-comprehension, which is evaluated straight away, would be 
much more idiomatic for repeated element-wise addition (or numpy arrays for 
that matter, if available). I'm **not advocating this piece of code**, just 
wondering whether there couldn't be a more informative way to make Python bail 
out instead of the segfault? (In my real application, it took me a while to 
figure where the problem was without a stack trace.)

--
messages: 246567
nosy: David Lukeš
priority: normal
severity: normal
status: open
title: segfault caused by nested calls to map()
type: crash
versions: Python 3.4

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