c++ - Error : An exception (first chance) at 0x76f6f9d2 in Boost_Mutex.exe: 0xC0000008: An invalid handle was specified -

i write program test multithreading. in main function thread t created. in function d, in thread t, 2 threads tt , ttt created. function process runs in thread ttt . in process member function doanotherthing of class dat called. in thread tt member function doonething called.

when debug program, error occured: an exception (first chance) @ 0x76f6f9d2 in boost_mutex.exe: 0xc0000008: invalid handle specified.

sometimes this error occured instead of error above :

run-time check failure #2 - stack around variable 'odat' corrupted. 

can me solve problem , modify codes?

these codes:

"dat.h"

#pragma once   #ifndef dat_h #define dat_h  #include <boost\thread\thread.hpp> using namespace std;  class dat  {  public:     dat();     ~dat();     void doonething();     void doanotherthing (); private:     boost::mutex omutex;      int x; }; #endif // dat_h 

"dat.cpp"

#include "dat.h"  dat::dat() {  }  dat::~dat() {  }  void dat::doonething() {     x = 1;   }  void dat::doanotherthing() {     omutex.lock();     x = 2;     omutex.unlock(); } 

"main.cpp"

#include "dat.h" #include <boost\function.hpp>  struct parameter // parameters of function process , d {  dat* pdat; }; void process(void*pparam) {     // init parameter      parameter* puserparams = (parameter*)pparam;     puserparams->pdat->doanotherthing(); }  void d(void* pparam) {     // init parameter      parameter* puserparams = (parameter*)pparam;     boost::function<void()> f;     boost::thread ttt(process, (void*)&pparam);     f = boost::bind(&dat::doonething, puserparams->pdat);        // capture thread started     boost::thread tt(f);      ttt.join();     tt.join(); }  void main() {     dat odat;     parameter ppara ;     ppara.pdat = &odat;     boost::thread t(d,(void*)&ppara);     t.join(); } 

if have suggestions statement of quesion, pleas tell me , modify it. thank you

the main problem here line:

boost::thread ttt(process, (void*)&pparam); 

you take address of pparam (which pointer), yielding void**, , cast void*. c++ threading interface type-safe. fact have cast strong indicator you're doing wrong. (also, usage of void* on place. needed c threading interfaces, not c++.)

anyway, in process take parameter, points pparam, , pretend points ppara object. (why prefixed p anyway? it's not pointer!) reach pdat pointer, of course nonsense, because there's no parameter struct there in first place. pointer isn't valid, , doesn't point valid dat struct, means mutex in there isn't valid either, means internal thread handle isn't valid, crash need when try lock mutex.

here's how fix code: rid of void pointer , rid of casts. also, not strictly necessary, should rid of variable prefixes. redundant naming convention bad enough, incorrectly applied redundant naming convention disaster.

you have 1 more error: don't protect all accesses x mutex, one. useless. you've still got race condition. have protect accesses shared variable. also, should use lock_guard raii object instead of manually calling lock , unlock, can never forget unlock.