Re: [Boost-users] Problem with boost random library.

From: Joshua Little (ljoshua_at_[hidden])
Date: 2004-07-03 20:09:03

Joshua Little wrote:

> Joshua Little wrote:
>
>> Kent Holsinger wrote:
>>
>>> Joshua,
>>>
>>> The following works fine for me on Windows 2000 with GCC. It's just 
>>> your code turned into a complete program. That suggests the problem 
>>> is with your test case, not your use of the RNG.
>>>
>>> Note that this version will always produce the same output, since it 
>>> uses a default seed. If you want to produce different random 
>>> sequences, you'll need to seed the generator accordingly.
>>>
>>> Kent
>>>
>>> #include <iostream>
>>> #include <boost/random.hpp>
>>>
>>> int main(int ac, char** av) {
>>>   printf(" Die \n ");
>>>   try {
>>>     boost::mt19937 rng;thin air
>>>     boost::uniform_int<> six(1,6);
>>>     boost::variate_generator<boost::mt19937, boost::uniform_int<> >
>>>     die(rng, six);
>>>     int x = die();
>>>     printf(" Die %d\n ",x);
>>>   }
>>>   catch(...) {
>>>     std::cout << "exception" << std::endl;
>>>     printf(" Die exception \n ");
>>>   }
>>> }
>>>
>>>
>> You were correct. I put that code into its own program and it ran 
>> just fine.. so I'm not sure what the deal is in my test cases, I 
>> don't know why it would kill the output since its basically the exact 
>> same code. This is the strangest thing I've seen in a while and I 
>> really have no idea what might be the problem.
>>
>> Joshua.
>
>
> I hate to respond to my own mail but my brain woke up and I ran the 
> test through gdb and low and behold, in the test code its causing a 
> segfault.
> Program received signal SIGSEGV, Segmentation fault.
> 0x0046208f in 
> boost::variate_generator<boost::random::mersenne_twister<unsigned, 32, 
> 624, 397, 31, 2567483615, 11, 7, 2636928640, 15, 4022730752, 18, 
> 3346425566>, boost::uniform_int<int> 
> >::variate_generator(boost::random::mersenne_twister<unsigned, 32, 
> 624, 397, 31, 2567483615, 11, 7, 2636928640, 15, 4022730752, 18, 
> 3346425566>, boost::uniform_int<int>) (this=0x22d150, e=
>      {static word_size = <optimized out>, static state_size = 
> <optimized out>, static shift_size = <optimized out>, static mask_bits 
> = <optimized out>, static parameter_a = <optimized out>, static 
> output_u = <optimized out>, static output_s = <optimized out>, static 
> output_b = <optimized out>, static output_t = <optimized out>, static 
> output_c = <optimized out>, static output_l = <optimized out>, static 
> has_fixed_range = <optimized out>, x = {300933633, 1838352333, 
> 1039116329, 1822211541, 2902250641, 835884317, 743498041, 2037202853, 
> 140269601, 3129818989, 3468776265, 3042141813, 3597794481, 2144163517, 
> 462622297, 2597716549, 3720499777, 3305777933, 2019631721, 1995498261, 
> 1568860369, 1886915677, 891264889, 3303332069, 589975649, 2673363629, 
> 1613469065, 3473388469, 3774879985, 1195980285, 56300697, 1687438213, 
> 1437389441, 882253389, 3658296489, 1954175061, 3570011409, 3045544861, 
> 2419715513, 1563345445, 3228719265, 1118971373, 2592237513, 
> 3246084341, 2211530033, 1950934333, 3074468569, 2991510725, 
> 2662556353, 2490032525, 681035497, 4253883797, 1377190225, 510946013, 
> 3078867961, 1910438757, 2109239521, 2068762925, 2414463497, 
> 3884072501, 1051296113, 1254122621, 94884121, 3726226949, 3738829569, 
> 2310829261, 1386541353, 2138911445, 2779481489, 3853734429, 
> 1575041593, 3616113829, 427858209, 2363640941, 2609232969, 284195701, 
> 1112329649, 3416503229, 368346969, 2265507653, 2099557185, 3334395917, 
> 2950212457, 2090768405, 1892538833, 2729970013, 2939566201, 
> 1203920357, 3008287073, 1746966445, 2709143177, 3264874677, 
> 2961123825, 4108767997, 2827668889, 3509610629, 1637315457, 
> 1252395853, 1087829417, 3427093845, 1707163153, 2314637469, 
> 2422654649, 2703066917, 195500449, 3938300653, 1324044489, 1985144309, 
> 3691288113, 25018941, 1456382937, 2779003333, 892748737, 2712014477, 
> 4014198761, 3670364821, 2278142545, 2900551645, 3747013881, 657391717, 
> 3289215457, 527277613, 1509749513, 3673101109, 2292257393, 2841411965, 
> 3542354457, 4067973893, 2718245889, 619897293, 3452123689, 3916605397, 
> 1797994129, 972099357, 3001717561, 3263875493, 2667960865, 2112117101, 
> 3251840329, 339906677, 723033777, 1635193021, 686751833, 3938503749, 
> 2466780225, 985695501, 1475949673, 1319193877, 1965673169, 3163883101, 
> 2600849785, 1086644965, 3222557281, 718660781, 244443017, 4213267893, 
> 690961137, 2613145597, 4237526681, 1183944069, 1950553217, 2520971341, 
> 2995371689, 3047506517, 470380305, 1564659101, 3767312313, 2490453029, 
> 3955022497, 938885101, 2438805961, 1566538485, 430499633, 120561469, 
> 3413482713, 2197724869, 1924801729, 2007907213, 3944274153, 
> 1590855573, 655237969, 560882909, 3311599097, 354682213, 3347280609, 
> 3824773933, 2757303305, 1037101109, 71934833, 3484786301, 737755929, 
> 572260357, 3161539841, 3962982093, 944407337, 1602034901, 4001097617, 
> 730582045, 3295472697, 3211857573...}, i = 624}, d={_min = 1, _max = 
> 6, _range = 5})
>    at e:/boost_1_31_0/boost/random/variate_generator.hpp:103
> 103         : _eng(decorated_engine(e)), _dist(d) { }
> (gdb)
>
I was wondering if anyone had any advice on how to track down this 
problem. I'm not sure why it works fine in a stand alone app but within 
my game it causes the segfault. I don't see anything that really looks 
suspicious, the part of the app that I was using is just straight c++, 
its not in the graphics code or other game logic and the segfault seems 
to occur in the constructor. I'm linking into  a graphics/game engine 
but even if I am just testing the ship library by itself in a test case 
it had the segfault. I can't think of what might be the problem, I'm not 
doing anything wierd as far as I know and I'm honestly not sure how the 
constructor could segfault since I have plenty of memory. I've only used 
1.31.0 so I'm not sure if the nightly CVS might work better but since I 
can use the variate generator in a stand alone app I think I must just 
be using it wrong.
Any help would be appreciated.
Joshua