parallel_sort example throws segmentation fault

[mloskot]

Hi,

I'm trying to run example of parallel_sort function presented in the reference manual in chapter 3.10 parallel_sort Template Function and everytime I run it, it crashes with segmentation fault.

I'm using TBB 2.1 installed from package for Ubuntu 9.10 64-bit with GCC 4.4.1.

1) Here is example program:

#include
#include
using namespace tbb;
int main()
{
const int N = 100000;
float a;
for( int i = 0; i < N; i++ ) {
a = std::sin((double)i);
}
parallel_sort(a, a + N);
}

2) Compilation commands, I tried both:

g++ -O2 -DNDEBUG -o sort_array sort_array.cpp -ltbb
g++ -O0 -g -DTBB_USE_DEBUG -o sort_array sort_array.cpp -ltbb

3) Backtrace from GDB:

$ gdb ./sort_array

(gdb) run
Starting program: /home/mloskot/workshop/tbb/parallel_sort/sort_array
[Thread debugging using libthread_db enabled]

Program received signal SIGSEGV, Segmentation fault.
tbb::task_group_context::init (this=0x7ffffff9c4e0) at ../../src/tbb/task.cpp:3124
3124 ../../src/tbb/task.cpp: No such file or directory.
in ../../src/tbb/task.cpp
(gdb) bt
#0 tbb::task_group_context::init (this=0x7ffffff9c4e0) at ../../src/tbb/task.cpp:3124
#1 0x00000000004013ff in task_group_context (this=0x7ffffff9c4e0, relation_with_parent=tbb::task_group_context::bound)
at /usr/include/tbb/task.h:284
#2 0x0000000000401be4 in tbb::internal::parallel_quick_sort > (begin=0x7ffffff9c6a0,
end=0x7fffffffe120, comp=...) at /usr/include/tbb/parallel_sort.h:155
#3 0x0000000000401b23 in tbb::parallel_sort > (begin=0x7ffffff9c6a0, end=0x7fffffffe120,
comp=...) at /usr/include/tbb/parallel_sort.h:203
#4 0x0000000000401ab3 in tbb::parallel_sort (begin=0x7ffffff9c6a0, end=0x7fffffffe120)
at /usr/include/tbb/parallel_sort.h:219
#5 0x0000000000401363 in main () at sort_array.cpp:12

I tested similar example but based on std::vector and it crashes in the same way:

#include
#include
#include
using namespace tbb;
int main()
{
const int N = 100000;
std::vector a(N);
for( int i = 0; i < N; i++ )
{
a = std::sin(double(i));
}
parallel_sort(a.begin(), a.end());
}

Could anyone help me to find to where is the problem? In TBB or in my environenment/installation?

I tried to find similar reports in the archive but noting comes out for parallel_sort and segmentation fault

[Alexey-Kukanov · Accepted solution]

Since you use TBB 2.1, you have to initialize TBB first. Include tbb/task_scheduler_init.h into the source file, and add the following line to the very beginning of main():

task_scheduler_init TBBinit;

In TBB 2.2, initialization became optional. Ask the package maintainer for a newer version.

BTW, you would get more meaningful diagnostics if you linked with the debug version of TBB (-ltbb_debug), in case it is provided in the package you use.

[mloskot]

Alex,

Your suggestion solves the problem, of course. Reading newer docs and using older library, I missed thatimportant change and that before 2.2 the scheduler initialization is required.

Regarding linking to debug version of the library, I can't do it because this binary is not provided in the Ubuntu 9.10 packages I'm using now. However, the upcoming Ubuntu 10.04 does bring TBB 2.2.

Thank you very much.

[Alexey-Kukanov]

Regarding linking to debug version of the library, I can't do it because this binary is not provided in the Ubuntu 9.10 packages I'm using now.

But, there is also libtbb-dev and libtbb2-dbg packages whichyou could download and install - I guess some of those should contain the debug version.

[mloskot]

Yes, I know about these related packages. I have a all of them installed in fact. The libtbb2-dbg is debugging symbols only package but, AFAIK, it's not a different configuration of the library binary.

[anthony123]

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