Comments (6)
Hi @koadman ,
Could you please share the code to reproduce the bug?
Thanks,
Prashant
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Hi Prashant thanks for the quick reply. I've had some difficulty isolating the exact same conditions from the rest of the codebase I'm working on but have now found two small-ish test cases that reproduce what look like a very similar or possibly the same issue.
The first is given in cqf_debug.cpp, which I am building as:
g++ cqf_debug.cpp -o cqf_debug -O0 -g3 -I. /home/koadman/software/cqf/obj/*.o -std=c++11 -I/home/koadman/software/cqf/include/ -pthread -lz -lssl -lcrypto -lm
with gcc version 5.4.0 20160609 on intel x64.
When I run it I see:
gdb ./cqf_debug
...
Reading symbols from ./cqf_debug...done.
(gdb) r keys_1.txt keys_2.txt
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Resizing the CQF.
Resizing the CQF.
Resizing the CQF.
Resizing the CQF.
Program received signal SIGSEGV, Segmentation fault.
0x00000000004036a1 in shift_remainders (qf=0x7fffffffd8d0, start_index=7692, empty_index=7680) at src/gqf.c:711
711 *REMAINDER_WORD(qf, last_word) = shift_into_b(*REMAINDER_WORD(qf, last_word-1),
(gdb) bt
#0 0x00000000004036a1 in shift_remainders (qf=0x7fffffffd8d0, start_index=7692, empty_index=7680) at src/gqf.c:711
#1 0x0000000000405717 in insert1 (qf=0x7fffffffd8d0, hash=493509468, runtime_lock=4 '\004') at src/gqf.c:1372
#2 0x000000000040746b in qf_insert (qf=0x7fffffffd8d0, key=493509468, value=0, count=1, flags=4 '\004') at src/gqf.c:1922
#3 0x00000000004017f4 in main (argc=3, argv=0x7fffffffde08) at cqf_debug.cpp:44
The interesting thing is that if I comment out the code block that creates and loads keys to the first QF, then the 2nd QF does not segfault. Possibly there is some global or file-scoped variable that's creating an unexpected dependency between the two QFs?
cqf_debug.cpp.gz
keys_2.txt.gz
keys_1.txt.gz
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The second, possibly related problem I have isolated into a small test example happens when merging two QFs. As above, compiling with:
g++ cqf_debug2.cpp -o cqf_debug2 -O0 -g3 -I. /home/koadman/software/cqf/obj/*.o -std=c++11 -I/home/koadman/software/cqf/include/ -pthread -lz -lssl -lcrypto -lm
and running:
gdb ./cqf_debug2
...
Reading symbols from ./cqf_debug2...done.
(gdb) r
...
Program received signal SIGSEGV, Segmentation fault.
0x0000000000403c1b in run_end (qf=0x7fffffffdc60, hash_bucket_index=80) at src/gqf.c:601
601 runend_block_offset = bitselectv(get_block(qf,
(gdb) bt
#0 0x0000000000403c1b in run_end (qf=0x7fffffffdc60, hash_bucket_index=80) at src/gqf.c:601
#1 0x0000000000406544 in insert (qf=0x7fffffffdc60, hash=330765, count=16, runtime_lock=9 '\t') at src/gqf.c:1444
#2 0x0000000000407eb0 in qf_insert (qf=0x7fffffffdc60, key=330765, value=0, count=16, flags=9 '\t') at src/gqf.c:1924
#3 0x000000000040a0a6 in qf_multi_merge (qf_arr=0x621c20, nqf=2, qfr=0x7fffffffdc60) at src/gqf.c:2498
#4 0x00000000004018ba in merger (cqf1="cqf_2.1", cqf2="cqf_2.2", cqf_out="cqf_2.merged") at cqf_debug2.cpp:27
#5 0x0000000000401af7 in main (argc=1, argv=0x7fffffffde28) at cqf_debug2.cpp:36
(gdb)
cqf_debug2.cpp.gz
cqf_1.1.gz
cqf_1.2.gz
cqf_2.1.gz
cqf_2.2.gz
(the above files need to be unzipped first of course)
interestingly, I see a similar behavior as before, where if I comment out the merge of the first two QFs then the 2nd merge is able to complete successfully, otherwise it segfaults.
from cqf.
quick update: i still have these problems. I have been able to work around them by doing two things:
- only insert to a single CQF per program invocation
- avoid CQF auto-resizing
of course a solution that eliminates the segfault would be preferable!
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Hey,
I had this same issue, and I think it derives from some reliance on the buffer's state. I changed the malloc call for the filter's buffer to a calloc call and this issue disappeared.
from cqf.
cool! maybe send a pull request?
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