Bdb btree with DB_INIT_CDB crashes on concurrent write

Question

Hi,
I am having issues with bdb and then locking mechanisms.
The following code results in either a seg fault, or what looks like a deadlock/endless loop
#include <iostream>
#include "db_cxx.h"
#include <boost/thread.hpp>
using namespace std;
void thread_instance(Db* db, double start){
double s = start;
double finish = start + 5000;
for(int x=s; x < finish ; x++){
Dbt key(&x, sizeof(double));
Dbt ddata(&x, sizeof(double));
db->put(NULL, &key, &ddata, 0);
int
compare_double(DB dbp, const DBT a,const DBT *b){
double ai, bi;
memcpy(&ai, a->data, sizeof(double));
memcpy(&bi, b->data, sizeof(double));
return (ai > bi ? 1 : ((ai < bi) ? -1 : 0));
int main(){
system("rm data/*");
u_int32_t env_flags = DB_CREATE | DB_INIT_MPOOL | DB_INIT_CDB;
DbEnv* env = new DbEnv(0);
env->set_cachesize(0, 2000000, 1);
u_int32_t m = 0;
env->open("data/", env_flags, 0);
Db* db = new Db(env, 0);
db->set_bt_compare(compare_double);
db->set_flags(DB_DUPSORT);
db->set_pagesize(32768);
db->set_dup_compare(compare_double);
u_int32_t oFlags = DB_CREATE;
try {
db->open(NULL, "db", NULL, DB_BTREE, oFlags, 0);
} catch (DbException &e) {
} catch (std::exception &e) {
vector<boost::thread*> threads;
for(int x=0; x < 3; x++){
threads.push_back(new boost::thread(boost::bind(&thread_instance, db, (x *5000))));
for(int x=0; x < threads.size(); x++){
threads[x]->join();
I have tried DB_INIT_LOCK as well, but with the same results.
What is going on here?

Answer 1

I forgot to include the stack trace:
Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000019
[Switching to process 34816]
0x00000001002e36a7 in __bamc_put ()
(gdb) ba
#0 0x00000001002e36a7 in __bamc_put ()
#1 0x0000000100386689 in __dbc_iput ()
#2 0x0000000100387a6c in __dbc_put ()
#3 0x0000000100383092 in __db_put ()
#4 0x0000000100397888 in __db_put_pp ()
#5 0x00000001002cee59 in Db::put ()
#6 0x0000000100001f88 in thread_instance (db=0x1007006c0, start=5000) at src/main.cpp:16
#7 0x0000000100698254 in thread_proxy ()
#8 0x00007fff80cb9456 in pthreadstart ()
#9 0x00007fff80cb9309 in thread_start ()