segmenation fault in threading simulation

[saphiroth]

Hi,
I wrote a program that simulates threading. I have 4 "threads" and all they do is write 1's and 0's into an array. I wrote a scheduler that creates a round robin run of the threads. Thread T1 writes 1's into the Buffer and if incouters a 0 then it blocks 'B' and if the goal of writing a certain amount of 1's is complete is sends a 'C' to the scheduler. T2 writes 0's and does that same thing. T3 is just like T1 and T4 is just like T2. If a thread finishes all of its writes it sends a 'D' to scheduler. For some reason I get a segmenation fault and can't find the reason. Please help.

Thank you.

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <setjmp.h>

//initialize TurnArray
char TurnArray[4] = {'R','R','R','R'};
jmp_buf env0,env1,env2,env3;
int Buffer[50];
int Buffer2[100];
void Scheduler(char status,int ThreadID);

int main(){

void T1(void);
void T2(void);
void T3(void);
void T4(void);


Scheduler('*',-1);

}//main



void T1(){

int GoalArray[3] = {10,20,30};
int temp = (int)((rand()*3)%3);
int Goal = GoalArray[temp];
int Total, GoalCount, position, x, a, envReturn = 0;

for(a;a<sizeof(Buffer);a++){
Buffer[a] = 0;
}//for

while(Total <= 1000){
GoalCount = 0;
for(x;GoalCount<=Goal;x++){
if(x < 50){
if(Buffer[x] == 0){
Buffer[x] = 1;
GoalCount++;
}//if
else{
envReturn = setjmp(env0);
if(envReturn == 0){
Scheduler('B',0);
}//if
}//else
}
else{
x = 0;
if(Buffer[x] == 0){
Buffer[x] = 1;
GoalCount++;
}//if
else{
envReturn = setjmp(env0);
if(envReturn == 0){
Scheduler('B',0);
}//if
}//else
}
}//for

envReturn = setjmp(env0);
if(envReturn == 0){
Scheduler('C',0);
}//if
else{
Total = Total + Goal;
}//else
}//while

envReturn = setjmp(env0);
if(envReturn == 0){
printf("Thread 1 is done");
Scheduler('D',0);
}//if
else{
Scheduler('D',0);
}
}//T1

void T2(){

int GoalArray[3] = {10,20,30};
int temp = (int)((rand()*3)%3);
int Goal = GoalArray[temp];
int Total, GoalCount, position, x = 0;
int envReturn;

while(Total <= 1000){
GoalCount = 0;
for(x;GoalCount<=Goal;x++){
if(x < 50){
if(Buffer[x] == 1){
Buffer[x] = 0;
GoalCount++;
}//if
else{
envReturn = setjmp(env1);
if(envReturn == 0){
Scheduler('B',1);
}//if
}//else
}
else{
x = 0;
if(Buffer[x] == 1){
Buffer[x] = 0;
GoalCount++;
}//if
else{
envReturn = setjmp(env1);
if(envReturn == 0){
Scheduler('B',1);
}//if
}//else
}
}//for

envReturn = setjmp(env1);
if(envReturn == 0){
Scheduler('C',1);
}//if
else{
Total = Total + Goal;
}//else
}//while

envReturn = setjmp(env1);
if(envReturn == 0){
printf("Thread 2 is done");
Scheduler('D',1);
}//if
else{
Scheduler('D',1);
}
}//T2

void T3(){

int GoalArray[3] = {15,25,35};
int temp = (int)((rand()*3)%3);
int Goal = GoalArray[temp];
int Total, GoalCount, position, x = 0;
int envReturn;
int a = 0;

for(a;a<sizeof(Buffer2);a++){
Buffer2[a] = 0;
}//for

while(Total <= 1500){
GoalCount = 0;
for(x;GoalCount<=Goal;x++){
if(x < 50){
if(Buffer2[x] == 0){
Buffer2[x] = 1;
GoalCount++;
}//if
else{
envReturn = setjmp(env2);
if(envReturn == 0){
Scheduler('B',2);
}//if
}//else
}
else{
x = 0;
if(Buffer2[x] == 0){
Buffer2[x] = 1;
GoalCount++;
}//if
else{
envReturn = setjmp(env2);
if(envReturn == 0){
Scheduler('B',2);
}//if
}//else
}
}//for

envReturn = setjmp(env2);
if(envReturn == 0){
Scheduler('C',2);
}//if
else{
Total = Total + Goal;
}//else
}//while

envReturn = setjmp(env2);
if(envReturn == 0){
printf("Thread 3 is done");
Scheduler('D',2);
}//if
else{
Scheduler('D',2);
}
}//T3

void T4(){

int GoalArray[3] = {15,25,35};
int temp = (int)((rand()*3)%3);
int Goal = GoalArray[temp];
int Total, GoalCount, position, x = 0;
int envReturn;


while(Total <= 1500){
GoalCount = 0;
for(x;GoalCount<=Goal;x++){
if(x < 50){
if(Buffer2[x] == 1){
Buffer[x] = 0;
GoalCount++;
}//if
else{
envReturn = setjmp(env3);
if(envReturn == 0){
Scheduler('B',3);
}//if
}//else
}
else{
x = 0;
if(Buffer[x] == 1){
Buffer[x] = 0;
GoalCount++;
}//if
else{
envReturn = setjmp(env3);
if(envReturn == 0){
Scheduler('B',3);
}//if
}//else
}
}//for

envReturn = setjmp(env3);
if(envReturn == 0){
Scheduler('C',3);
}//if
else{
Total = Total + Goal;
}//else
}//while

envReturn = setjmp(env3);
if(envReturn == 0){
printf("Thread 4 is done");
Scheduler('D',3);
}//if
else{
Scheduler('D',3);
}
}//T4



void Scheduler(char status,int ThreadID){

if(status == '*' && ThreadID == -1){
T1();
}//if

if(TurnArray[0] == 'D' && TurnArray[1] == 'D' && TurnArray[2] == 'D' && TurnArray[3] == 'D'){
exit(0);
}

if(status == 'C'){
TurnArray[ThreadID] = 'R'; //if C
printf("State: %c, ID: %d, Condition: %c",status, ThreadID, 'R');
if(ThreadID == 0){
if(env1 == NULL){
T2();
}
else{
longjmp(env1, 2);
}
}//if
else if(ThreadID == 1){
if(env2 == NULL){
T3();
}
else{
longjmp(env2, 2);
}
}//if
else if(ThreadID == 2){
if(env3 == NULL){
T4();
}
else{
longjmp(env3, 2);
}
}//if
else if(ThreadID == 3){
if(env0 == NULL){
T1();
}
else{
longjmp(env0, 2);
}
}//if

}//if
else if(status == 'B'){
TurnArray[ThreadID] = 'W'; //if B
printf("State: %c, ID: %d, Condition: %c",status, ThreadID, 'W');
if(ThreadID == 0){
if(env1 == NULL){
T2();
}
else{
TurnArray[1] = 'R';
//printf("State: %c, ID: %d, Condition: %c",'B', 1, 'R');
longjmp(env1, 2);
}
}//if
else if(ThreadID == 1){
if(env2 == NULL){
T3();
}
else{
TurnArray[0] = 'R';
//printf("State: %c, ID: %d, Condition: %c",'B', 0, 'R');
longjmp(env2, 2);
}
}//if
else if(ThreadID == 2){
if(env3 == NULL){
T4();
}
else{
TurnArray[3] = 'R';
//printf("State: %c, ID: %d, Condition: %c",'B', 3, 'R');
longjmp(env3, 2);
}
}//if
else if(ThreadID == 3){
TurnArray[2] = 'R';
//printf("State: %c, ID: %d, Condition: %c",'B', 2, 'R');
longjmp(env0, 2);
}//if

}//else if
else{ //if D
TurnArray[ThreadID] = 'D';
printf("State: %c, ID: %d, Condition: %c",status, ThreadID, 'F');
if(ThreadID == 0){
longjmp(env1, 2);
}//if
else if(ThreadID == 1){
longjmp(env2, 2);
}//if
else if(ThreadID == 2){
longjmp(env3, 2);
}//if
else if(ThreadID == 3){
longjmp(env0, 2);
}//if
}//else

}//Scheduler

 

[Salem]

Please use the [tt][ignore]

[/ignore][/tt] tags when posting code.

--

 

[xwb]

In all your T1 you have

int Total, GoalCount, position, x, a, envReturn = 0;

for(a;a<sizeof(Buffer);a++){
Buffer[a] = 0;
}//for
while(Total <= 1000){
GoalCount = 0;
for(x;GoalCount<=Goal;x++){
if(x < 50){ 
if(Buffer[x] == 0){
Buffer[x] = 1;
GoalCount++;
}//if

a and x are not initialized. T2, T3 and T4 do not have the same bug.