Something between your mail client and my mail client hates us:
On Thu, Jan 07, 2016 at 03:29:49PM -0800, curtis_ovid_...@yahoo.com wrote:
> This code sometimes segfaults, sometimes tells me it's a malloc error:
> my @primes = grep { .is-prime }, 1 .. *; my @p = gather for 4000, 5, 100,
> 2000 -> $n { take start { @primes[$n] }; }; .say for await @p; Yes, I know
> the code is stupid (since one promise might be trying to access data that's
> not yet been calculated), but I would hope for something other than random
> error messages :)
Nice find. ASAN says this, and memory corruption combined with concurrency
would explain the non-deterministic results you're reporting:
$ ./perl6-m -Ilib -e 'my @primes = grep { .is-prime }, 1 .. *; my @p = gather
for 4000, 5, 100, 2000 -> $n { take start { @primes[$n] }; }; .say for await
@p;'
=================================================================
==16988==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x619000168e80 at pc 0x7feef89ff829 bp 0x7feef24dbff0 sp 0x7feef24dbfe8
READ of size 8 at 0x619000168e80 thread T1
#0 0x7feef89ff828 in at_pos src/6model/reprs/MVMArray.c:133
#1 0x7feeedba94fd (+0x74fd)
0x619000168e80 is located 0 bytes to the right of 1024-byte region
[0x619000168a80,0x619000168e80)
freed by thread T3 here:
#0 0x7feef94ae8e6 in __interceptor_realloc
../../.././libsanitizer/asan/asan_malloc_linux.cc:93
#1 0x7feef89fe3c6 in MVM_realloc src/core/alloc.h:20
#2 0x7feef8a011a9 in set_size_internal src/6model/reprs/MVMArray.c:334
#3 0x7feef8a020b9 in push src/6model/reprs/MVMArray.c:437
#4 0x7feef89ef36b in MVM_repr_push_o src/6model/reprconv.c:339
#5 0x7feeedb8e0cc (+0x40cc)
#6 0x7feef8b2f290 in MVM_jit_enter_code src/jit/compile.c:125
#7 0x7feef89211a2 in MVM_interp_run src/core/interp.c:5402
#8 0x7feef8951ce7 in start_thread src/core/threads.c:77
#9 0x7feef8bfa94d in uv__thread_start 3rdparty/libuv/src/unix/thread.c:49
#10 0x7feef7cbc9d0 in start_thread (/lib64/libpthread.so.0+0x79d0)
previously allocated by thread T1 here:
#0 0x7feef94ae8e6 in __interceptor_realloc
../../.././libsanitizer/asan/asan_malloc_linux.cc:93
#1 0x7feef89fe3c6 in MVM_realloc src/core/alloc.h:20
#2 0x7feef8a011a9 in set_size_internal src/6model/reprs/MVMArray.c:334
#3 0x7feef8a020b9 in push src/6model/reprs/MVMArray.c:437
#4 0x7feef88d36ba in MVM_interp_run src/core/interp.c:2207
#5 0x7feef8951ce7 in start_thread src/core/threads.c:77
#6 0x7feef8bfa94d in uv__thread_start 3rdparty/libuv/src/unix/thread.c:49
#7 0x7feef7cbc9d0 in start_thread (/lib64/libpthread.so.0+0x79d0)
Thread T1 created by T0 here:
#0 0x7feef947d6ea in __interceptor_pthread_create
../../.././libsanitizer/asan/asan_interceptors.cc:183
#1 0x7feef8bfaa52 in uv_thread_create 3rdparty/libuv/src/unix/thread.c:66
#2 0x7feef895203f in MVM_thread_run src/core/threads.c:126
#3 0x7feef88fbd2b in MVM_interp_run src/core/interp.c:3933
#4 0x7feef8b942dd in MVM_vm_run_file src/moar.c:304
#5 0x401a4f in main src/main.c:191
#6 0x7feef80f8d5c in __libc_start_main (/lib64/libc.so.6+0x1ed5c)
Thread T3 created by T0 here:
#0 0x7feef947d6ea in __interceptor_pthread_create
../../.././libsanitizer/asan/asan_interceptors.cc:183
#1 0x7feef8bfaa52 in uv_thread_create 3rdparty/libuv/src/unix/thread.c:66
#2 0x7feef895203f in MVM_thread_run src/core/threads.c:126
#3 0x7feef88fbd2b in MVM_interp_run src/core/interp.c:3933
#4 0x7feef8b942dd in MVM_vm_run_file src/moar.c:304
#5 0x401a4f in main src/main.c:191
#6 0x7feef80f8d5c in __libc_start_main (/lib64/libc.so.6+0x1ed5c)
SUMMARY: AddressSanitizer: heap-buffer-overflow src/6model/reprs/MVMArray.c:133
at_pos
Shadow bytes around the buggy address:
0x0c3280025180: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c3280025190: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c32800251a0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c32800251b0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c32800251c0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
=>0x0c32800251d0:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c32800251e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c32800251f0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c3280025200: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c3280025210: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x0c3280025220: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Contiguous container OOB:fc
ASan internal: fe
==16988==ABORTING
Nicholas Clark
