调试一个bad_alloc错误
Debugging a bad_alloc error c++
当我运行我的代码似乎一切都很好，但经过一定数量的时间步(通常~100，但每次不同的数字)，我得到错误:
"抛出'std::bad_alloc'实例后终止调用"
不太确定如何去调试这个，因为它不会发生在同一点每次代码运行。我将发布我的代码，但它相当长，而且无可否认有点混乱(这是我第一次真正尝试用c++编写程序)，但我将尝试解释结构，以及我预计最可能出现错误的地方。
基本结构是，我有一个"birds"(我定义的一个类)数组，它们通过一些相当复杂的计算选择如何在每个时间步骤更新自己。在此过程中，它会定期调用getVisualState函数来更新每只鸟存储为其"视觉状态"的链表。我相信这是我在模拟过程中唯一一次动态分配内存，所以我猜这很有可能是错误的来源。函数Bird::resetVisualState()应该在它被使用后清除分配的内存(但它似乎不像我内存耗尽，至少在任务管理器中监视它)。
如果有人能看到任何他们认为可能是问题的根源，那将是非常棒的，或者如果不只是任何建议，我应该如何实际调试这个!
#include <iostream>
#include <cmath>
#include <gsl/gsl_rng.h>
#include <gsl/gsl_randist.h>
#include <ctime>
#include <vector>
#include <algorithm>
#include <fstream>
#include "birdClasses.h"
using namespace std;
/*
nBirds, nSteps, nF, v, dt, birdRad defined in "birdClasses.h"
*/
//define other parameters.
const int nSensors = 20;
const int nMoves = 3; //no. possible moves at each step.
double dTheta = 15*M_PI/180.0; //angle that birds can change their orientation by in a timestep.
double moves[nMoves] = {-dTheta, 0, dTheta}; //possible moves.
double noise = 0.0;
double initBoxX = 20, initBoxY = 20; //size of initial box particles are placed in.
double sensorFrac[nSensors];
double sensorRef[nSensors];
double sensorRange = 2*M_PI/((double)nSensors);
int counter = 0;
int nps = numStates(nMoves,nF);
int *possibleStates = new int[nps];
//variables to record positions and orientations.
double xPositions[nSteps][nBirds], yPositions[nSteps][nBirds], orientations[nSteps][nBirds];
//array to keep track of which collisions are possible.
int couldCollide[nF][nBirds][nBirds];
//function prototypes
bool checkCollision(int i, int nFut, Bird *birds, double xi, double yi);
unsigned long int getVisualState(Bird *birdList, int nFut, int i, double cX, double cY, double cAng);
void updateTree(double exploreX, double exploreY, double exploreO, Bird *bird, int bn, int nFut);
int main()
{
sensorRef[0] = sensorRange;
for(int u=1; u<nSensors; u++) sensorRef[u] = sensorRef[u-1] + sensorRange;
//set up GSL random number generator.
const gsl_rng_type * Tr;
gsl_rng * RNG;
gsl_rng_env_setup();
Tr = gsl_rng_default;
RNG = gsl_rng_alloc (Tr);
gsl_rng_set(RNG,time(NULL));
//set up output
ofstream output("output.txt");
//initialize birds in a box randomly, all with the same orientation.
Bird birdList[nBirds];
for(int i=0; i<nBirds; i++) {
birdList[i].set_position(gsl_ran_flat(RNG,0,initBoxX),gsl_ran_flat(RNG,0,initBoxY));
}
//ACTUAL CODE
int uniqueVisStates[nMoves];
double cX, cY, fX, fY, exploreX, exploreY, exploreO;
//main time step loop
for(int ts=0; ts<nSteps; ts++) {
//save current positions
for(int i=0; i<nBirds; i++) {
xPositions[ts][i] = birdList[i].get_xPos();
yPositions[ts][i] = birdList[i].get_yPos();
orientations[ts][i] = birdList[i].get_orientation();
birdList[i].updateFuture();
}
//update list of possible collisions.
for(int nFut=0; nFut<nF; nFut++) {
for(int i=0; i<nBirds; i++) {
cX = birdList[i].get_xPos(); cY = birdList[i].get_yPos();
counter = 0;
for(int j=0; j<nBirds; j++) {
if(i==j) {
continue;
} else {
fX = birdList[j].get_futureX(nFut); fY = birdList[j].get_futureY(nFut);
if((cX-fX)*(cX-fX)+(cY-fY)*(cY-fY) < ((nFut+1)*v*dt+2*birdRad)*((nFut+1)*v*dt+2*birdRad)) {
couldCollide[nFut][i][counter]=j;
counter++;
}
}
}
if(counter < nBirds) couldCollide[nFut][i][counter]=-1;
}
}
//loop over birds to choose how they update their orientation.
for(int bn=0; bn<nBirds; bn++) {
//loop over possible moves bird can make NOW.
for(int l=0; l<nMoves; l++) {
uniqueVisStates[l]=0;
}
for(int mn=0; mn<nMoves; mn++) {
for(int l=0; l<nps; l++) {
possibleStates[l]=0;
}
counter = 0;
exploreO = birdList[bn].get_orientation() + moves[mn];
exploreX = birdList[bn].get_xPos() + cos(exploreO)*v*dt;
exploreY = birdList[bn].get_yPos() + sin(exploreO)*v*dt;
updateTree(exploreX,exploreY,exploreO,&birdList[0],bn,0);
vector<int> visStates (possibleStates,possibleStates+counter);
vector<int>::iterator it;
sort (visStates.begin(),visStates.end());
it = unique(visStates.begin(),visStates.end());
uniqueVisStates[mn] = distance(visStates.begin(),it);
}
int maxInd = 0, maxVal = uniqueVisStates[0];
for(int h=1; h<nMoves; h++) {
if(uniqueVisStates[h] > maxVal) {
maxInd = h; maxVal = uniqueVisStates[h];
} else if(uniqueVisStates[h]==maxVal) {
if(abs(moves[h])<abs(moves[maxInd])) {
maxInd = h;
}
}
}
birdList[bn].update_Orientation(moves[maxInd]);
birdList[bn].update_Pos(birdList[bn].get_xPos()+cos(birdList[bn].get_orientation())*v*dt,birdList[bn].get_yPos()+sin(birdList[bn].get_orientation())*v*dt);
}
for(int bn=0; bn<nBirds; bn++) birdList[bn].finishUpdate();
cout << ts << "n";
}
//OUTPUT DATA INTO A TEXT FILE.
for(int ts=0; ts<(nSteps-1); ts++) {
for(int bn=0; bn<nBirds; bn++) {
output << xPositions[ts][bn] << " " << yPositions[ts][bn] << " " << orientations[ts][bn] << "n";
}
}
delete[] possibleStates;
return 0;
}
bool checkCollision(int i, int nFut, Bird *birds, double xi, double yi) {
int cond = 1; int index, counti=0;
while(cond) {
index = couldCollide[nFut][i][counti];
if(index==-1) break;
double xj = birds[index].get_futureX(nFut);
double yj = birds[index].get_futureY(nFut);
if((xi-xj)*(xi-xj)+(yi-yj)*(yi-yj) < 4*birdRad*birdRad) {
return 1;
}
counti++;
if(counti==nBirds) break;
}
return 0;
}
unsigned long int getVisualState(Bird *birdList, int nFut, int i, double cX, double cY, double cAng) {
//finds the visual state of bird i based on its current "exploring position" and the predicted positions of other birds at timestep nFut.
//visual state is defined by discretizing the bird's field of view into nSensors (relative to current orientation) and creating a vector of
//0s and 1s depending on whether each sensor is < half covered or not. This is then converted to an integer (as we are actually interested only
//in the number of unique visual states.
double relX, relY, relDist, dAng, s, dTheta, ang1, ang2;
//clear current visual state.
birdList[i].resetVisualState();
for(int j=0; j<nBirds; j++) {
if(i==j) continue;
relX = birdList[j].get_futureX(nFut)-cX;
relY = birdList[j].get_futureY(nFut)-cY;
relDist = sqrt(relX*relX+relY*relY);
dAng = acos((cos(cAng)*relX+sin(cAng)*relY)/relDist);
dTheta = atan(birdRad/relDist);
s = cos(cAng)*relY - sin(cAng)*relX;
if( s<0 ) dAng = 2*M_PI-dAng;
ang1 = dAng - dTheta; ang2 = dAng + dTheta;
if( ang1 < 0 ) {
birdList[i].addInterval(0,ang2);
birdList[i].addInterval(2*M_PI+ang1,2*M_PI);
} else if( ang2 > 2*M_PI ) {
birdList[i].addInterval(0,fmod(ang2,2*M_PI));
birdList[i].addInterval(ang1,2*M_PI);
} else {
birdList[i].addInterval(ang1,ang2);
}
}
Node *sI = birdList[i].get_visualState();
birdList[i].cleanUp(sI);
int ind1, ind2;
for(int k=0; k<nSensors; k++) sensorFrac[k]=0.0; //initialize.
while(sI->next->next != 0) {
ang1 = sI->value; ang2 = sI->next->value;
ind1 = floor(ang1/sensorRange); ind2 = floor(ang2/sensorRange);
if(ind2==nSensors) ind2--; //this happens if ang2 = 2pi (which can happen a lot).
if(ind1==ind2) {
sensorFrac[ind1] += (ang2-ang1)/sensorRange;
} else if(ind2-ind1==1) {
sensorFrac[ind1] += (sensorRef[ind1]-ang1)/sensorRange;
sensorFrac[ind2] += (ang2-sensorRef[ind1])/sensorRange;
} else {
sensorFrac[ind1] += (sensorRef[ind1]-ang1)/sensorRange;
sensorFrac[ind2] += (ang2-sensorRef[ind2-1])/sensorRange;
for(int y=ind1+1;y<ind2;y++) sensorFrac[y] = 1.0;
}
sI=sI->next->next;
}
//do final interval separately.
ang1 = sI->value; ang2 = sI->next->value;
ind1 = floor(ang1/sensorRange); ind2 = floor(ang2/sensorRange);
if(ind2==nSensors) ind2--; //this happens if ang2 = 2pi (which can happen a lot).
if(ind1==ind2) {
sensorFrac[ind1] += (ang2-ang1)/sensorRange;
} else if(ind2-ind1==1) {
sensorFrac[ind1] += (sensorRef[ind1]-ang1)/sensorRange;
sensorFrac[ind2] += (ang2-sensorRef[ind1])/sensorRange;
} else {
sensorFrac[ind1] += (sensorRef[ind1]-ang1)/sensorRange;
sensorFrac[ind2] += (ang2-sensorRef[ind2-1])/sensorRange;
for(int y=ind1+1;y<ind2;y++) sensorFrac[y] = 1.0;
}
int output = 0, multiplier = 1;
for(int y=0; y<nSensors; y++) {
if(sensorFrac[y]>0.5) output += multiplier;
multiplier *= 2;
}
return output;
}
void updateTree(double exploreX, double exploreY, double exploreO, Bird *bird, int bn, int nFut) {
double o,x,y;
if(checkCollision(bn,nFut,bird,exploreX,exploreY)) return;
int vs = getVisualState(bird,nFut,bn,exploreX,exploreY,exploreO);
possibleStates[counter] = vs;
counter++;
if(nFut < (nF-1)) {
for(int m=0; m<nMoves; m++) {
o = exploreO + moves[m];
x = exploreX + cos(o)*v*dt;
y = exploreY + sin(o)*v*dt;
updateTree(x,y,o,bird,bn,nFut+1);
}
} else {
return;
}
}
:
#ifndef BIRDCLASSES_H_INCLUDED
#define BIRDCLASSES_H_INCLUDED
#include <iostream>
#include <cmath>
using namespace std;
//DEFINE SOME GLOBAL PARAMETERS OF THE SIMULATION
const int nBirds = 50;
const int nF = 6; //number of future timesteps to consider.
const int nSteps = 200;
const double v = 20, dt = 0.1, birdRad = 0.2;
int numStates(int numMoves, int nFut) {
int num = 1; int multiplier = numMoves;
for(int i=1; i<nFut; i++) {
num += multiplier;
multiplier *= numMoves;
}
return num;
}
//Node class is just for a linked list (used in constructing the visual states),
class Node {
public:
int identifier; // 0 is left side of interval, 1 is right side
double value; //angular value.
Node *next; //pointer to the next interval.
void display(Node *start);
};
//printout linked list if necessary (mainly for debugging purposes).
void Node::display(Node *start) {
if(start != 0) {
double inter = start->value;
cout << inter << " ";
display(start->next);
}
}
//bird class.
class Bird {
double currX, currY;
double updatedX, updatedY;
double currOrientation;
double futureX[nF], futureY[nF];
Node *visualState;
public:
Bird() {
currOrientation=0.0; currX = 0.0; currY = 0.0;
visualState = new Node;
visualState->value = 0.0;
visualState->next = new Node;
visualState->next->value = 0.0;
visualState->next->next = 0;
}
Bird(double x, double y, double o) {
currX = x; currY = y; currOrientation = o;
visualState = new Node;
visualState->value = 0.0;
visualState->next = new Node;
visualState->next->value = 0.0;
visualState->next->next = 0;
}
void set_position(double x, double y) {
currX = x; currY = y;
}
double get_xPos() {
return currX;
}
double get_yPos() {
return currY;
}
double get_orientation() {
return currOrientation;
}
double get_futureX(int ts) {
return futureX[ts];
}
double get_futureY(int ts) {
return futureY[ts];
}
//return pointer to first node.
Node* get_visualState() {
return visualState;
}
void updateFuture() {
//use current orientation and position to update future positions.
for(int i=0; i<nF; i++) {
futureX[i] = currX + v*(i+1)*cos(currOrientation)*dt;
futureY[i] = currY + v*(i+1)*sin(currOrientation)*dt;
}
}
void update_Pos(double x, double y) {
updatedX = x;
updatedY = y;
}
//run this after all birds have updated positions:
void finishUpdate() {
currX = updatedX;
currY = updatedY;
}
void update_Orientation(double o) {
currOrientation += o;
}
//add the interval defined by [l r] to the visual state.
void addInterval(double l, double r) {
int placed = 0; double cL = 0.0; double cR = 0.0;
if(visualState->value==0.0 && visualState->next->value==0.0) { //then this is first interval to place.
visualState->value = l;
visualState->next->value = r;
placed = 1;
return;
}
Node *curr_L = visualState;
Node *prev_L = visualState;
while(placed==0) {
cL = curr_L->value;
cR = curr_L->next->value;
if(l<cL && r<cL) { //add new interval before this one.
Node *newRoot = new Node;
newRoot->value = l;
newRoot->identifier = 0;
newRoot->next = new Node;
newRoot->next->value = r;
newRoot->next->next = curr_L;
if(curr_L == visualState) {
visualState = newRoot;
} else {
prev_L->next->next = newRoot;
}
placed = 1;
} else if(l <= cL && r >= cR) {
curr_L->value = l;
curr_L->next->value = r;
placed = 1;
} else if(l <= cL && r <= cR) {
curr_L->value = l;
placed = 1;
} else if(l >= cL && r <= cR) {
placed = 1; //dont need to do anything.
} else if(l >= cL && l<=cR && r >= cR) {
curr_L->next->value = r;
placed = 1;
}
if(l > cR && r > cR) {
if(curr_L->next->next != 0) {
prev_L = curr_L;
curr_L = curr_L->next->next;
} else {
Node *newEndL = new Node;
newEndL->value = l;
newEndL->identifier = 0;
newEndL->next = new Node;
newEndL->next->value = r;
newEndL->next->identifier = 1;
newEndL->next->next = 0;
curr_L->next->next = newEndL;
placed = 1;
}
}
}
}
//remove any overlaps.
void cleanUp(Node *start) {
Node *NP, *NNP; NP = start->next->next;
if(NP==0) return;
NNP = start->next->next->next->next;
double cL = start->value, cR = start->next->value, nL = start->next->next->value, nR = start->next->next->next->value;
if(nL < cR) {
if(nR > cR) {
start->next->value = nR;
}
start->next->next = NNP;
}
if(NNP!=0) cleanUp(NP);
}
//reset the visual state.
void resetVisualState() {
Node *cNode = visualState;
Node *nNode = visualState->next;
while(nNode != 0) {
delete cNode;
cNode = nNode;
nNode = nNode->next;
}
delete cNode;
delete nNode;
visualState = new Node;
visualState->identifier = 0;
visualState->value = 0.0;
visualState->next = new Node;
visualState->next->identifier = 1;
visualState->next->value = 0.0;
visualState->next->next = 0;
return;
}
};
#endif // BIRDCLASSES_H_INCLUDED
或者如果不只是关于我应该如何调试这个的建议!
您可以尝试在gdb中设置catchpoint来捕获std::bad_alloc异常:
(gdb) catch throw bad_alloc
(参见设置捕获点)
如果您能够在gdb中复制这个bad_alloc，那么您可以查看bt以查看此异常的可能原因。
我认为这是一个逻辑错误，不一定与内存有关。
在void addInterval(double l, double r)中声明
Node *curr_L = visualState;
Node *prev_L = visualState;
这些指针现在将指向成员visualState所指向的对象。
之后将visualState更改为指向新创建的Node
Node *newRoot = new Node;
// ....
if(curr_L == visualState) {
visualState = newRoot;
但是你的指针curr_L和prev_L仍然会指向visualState之前指向的东西。只有在
处才需要更改这些指针if(curr_L->next->next != 0) {
prev_L = curr_L;
curr_L = curr_L->next->next;
与
相同if(WHATEVER_VISUAL_STATE_USED_TO_POINT_TO->next->next != 0) {
prev_L = curr_L;
curr_L = curr_L->next->next;
这是你的意图吗?您可以通过在编辑器中查找*curr_L = *来跟踪curr_L的赋值。
我建议在一个小数据样本上测试你的代码，并确保你的代码符合你的意图。使用调试器或跟踪输出。使用
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