Memory leak in C++ Threads, Used VALGRIND to debug - c++

Question

I have a thread system that keeps allways opened a certain amount of threads. The problem with this program si that it is having some memory leak problems. I am starting the program at around 8MB (RAM memory) and in 1 day i see it at 800MB. I used valgrind to track down this issue and i found the following while running this command time valgrind --leak-check=yes ./test2; :
I get this when i use 1000 treads and it is not even finishing.
Thread 157: status = VgTs_WaitSys
==16172== at 0x4160F8B: ??? (in /lib/libc-2.5.so)
==16172== by 0x40FF58F: _IO_file_underflow##GLIBC_2.1 (in /lib/libc-2.5.so)
==16172== by 0x40FFC8A: _IO_default_uflow (in /lib/libc-2.5.so)
==16172== by 0x410100C: __uflow (in /lib/libc-2.5.so)
==16172== by 0x40F48B5: _IO_getline_info (in /lib/libc-2.5.so)
==16172== by 0x40F4800: _IO_getline (in /lib/libc-2.5.so)
==16172== by 0x40F3779: fgets (in /lib/libc-2.5.so)
==16172== by 0x80496CF: exec(char const*) (in /home/pthread_test)
==16172== by 0x80498C2: thread_test(void*) (in /home/pthread_test)
==16172== by 0x40A911: start_thread (in /lib/libpthread-2.5.so)
==16172== by 0x417047D: clone (in /lib/libc-2.5.so)
Thread 158: status = VgTs_WaitSys
==16172== at 0x4160F8B: ??? (in /lib/libc-2.5.so)
==16172== by 0x40FF58F: _IO_file_underflow##GLIBC_2.1 (in /lib/libc-2.5.so)
==16172== by 0x40FFC8A: _IO_default_uflow (in /lib/libc-2.5.so)
==16172== by 0x410100C: __uflow (in /lib/libc-2.5.so)
==16172== by 0x40F48B5: _IO_getline_info (in /lib/libc-2.5.so)
==16172== by 0x40F4800: _IO_getline (in /lib/libc-2.5.so)
==16172== by 0x40F3779: fgets (in /lib/libc-2.5.so)
==16172== by 0x80496CF: exec(char const*) (in /home/pthread_test)
==16172== by 0x80498C2: thread_test(void*) (in /home/pthread_test)
==16172== by 0x40A911: start_thread (in /lib/libpthread-2.5.so)
==16172== by 0x417047D: clone (in /lib/libc-2.5.so)
When using just ./test2 (running without valgrind), absolutely all threads finishes and i can see in the debug.log that every thread finishes
tail debug.log
END:1972:191
END:1984:191
END:1992:191
END:1974:191
END:1986:191
END:1979:191
END:1993:191
END:1983:191
END:1999:191 <-- even thread 1999 finished
END:1991:191
When i am doing with 250 threads i get this at the end of the program
THREAD [1993] ending
THREAD [1983] ending
THREAD [1999] ending
THREAD [1991] ending
==23152== Thread 25:
==23152== Invalid free() / delete / delete[]
==23152== at 0x400579D: free (vg_replace_malloc.c:325)
==23152== by 0x3B59DD: ??? (in /lib/libc-2.5.so)
==23152== by 0x3B5556: ??? (in /lib/libc-2.5.so)
==23152== by 0x40013B2: _vgnU_freeres (vg_preloaded.c:62)
==23152== by 0x333A73: _Exit (in /lib/libc-2.5.so)
==23152== by 0x40AAF8: start_thread (in /lib/libpthread-2.5.so)
==23152== by 0x37547D: clone (in /lib/libc-2.5.so)
==23152== Address 0x409b2c8 is not stack'd, malloc'd or (recently) free'd
==23152==
==23152==
==23152== HEAP SUMMARY:
==23152== in use at exit: 160,850 bytes in 12,002 blocks
==23152== total heap usage: 20,151 allocs, 8,150 frees, 2,640,139 bytes allocated
==23152==
==23152== Thread 1:
==23152== 152 bytes in 1 blocks are possibly lost in loss record 2 of 8
==23152== at 0x4004EC2: calloc (vg_replace_malloc.c:418)
==23152== by 0x291FF9: _dl_allocate_tls (in /lib/ld-2.5.so)
==23152== by 0x40B026: pthread_create##GLIBC_2.1 (in /lib/libpthread-2.5.so)
==23152== by 0x80493DF: main (in /home/freelancer1/pthreads_test/test2)
==23152==
==23152== 20,000 bytes in 2,000 blocks are definitely lost in loss record 3 of 8
==23152== at 0x4005B83: malloc (vg_replace_malloc.c:195)
==23152== by 0x3105DF: strdup (in /lib/libc-2.5.so)
==23152== by 0x8049C56: file_put_contents(char*, char*, char*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x804981D: thread_test(void*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x40A911: start_thread (in /lib/libpthread-2.5.so)
==23152== by 0x37547D: clone (in /lib/libc-2.5.so)
==23152==
==23152== 20,000 bytes in 2,000 blocks are definitely lost in loss record 4 of 8
==23152== at 0x4005B83: malloc (vg_replace_malloc.c:195)
==23152== by 0x3105DF: strdup (in /lib/libc-2.5.so)
==23152== by 0x8049C56: file_put_contents(char*, char*, char*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x804944D: main (in /home/freelancer1/pthreads_test/test2)
==23152==
==23152== 20,000 bytes in 2,000 blocks are definitely lost in loss record 5 of 8
==23152== at 0x4005B83: malloc (vg_replace_malloc.c:195)
==23152== by 0x3105DF: strdup (in /lib/libc-2.5.so)
==23152== by 0x8049C56: file_put_contents(char*, char*, char*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x8049950: thread_test(void*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x40A911: start_thread (in /lib/libpthread-2.5.so)
==23152== by 0x37547D: clone (in /lib/libc-2.5.so)
==23152==
==23152== 26,890 bytes in 2,000 blocks are definitely lost in loss record 6 of 8
==23152== at 0x4005B83: malloc (vg_replace_malloc.c:195)
==23152== by 0x3105DF: strdup (in /lib/libc-2.5.so)
==23152== by 0x8049C64: file_put_contents(char*, char*, char*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x8049950: thread_test(void*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x40A911: start_thread (in /lib/libpthread-2.5.so)
==23152== by 0x37547D: clone (in /lib/libc-2.5.so)
==23152==
==23152== 30,890 bytes in 2,000 blocks are definitely lost in loss record 7 of 8
==23152== at 0x4005B83: malloc (vg_replace_malloc.c:195)
==23152== by 0x3105DF: strdup (in /lib/libc-2.5.so)
==23152== by 0x8049C64: file_put_contents(char*, char*, char*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x804981D: thread_test(void*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x40A911: start_thread (in /lib/libpthread-2.5.so)
==23152== by 0x37547D: clone (in /lib/libc-2.5.so)
==23152==
==23152== 42,890 bytes in 2,000 blocks are definitely lost in loss record 8 of 8
==23152== at 0x4005B83: malloc (vg_replace_malloc.c:195)
==23152== by 0x3105DF: strdup (in /lib/libc-2.5.so)
==23152== by 0x8049C64: file_put_contents(char*, char*, char*) (in /home/freelancer1/pthreads_test/test2)
==23152== by 0x804944D: main (in /home/freelancer1/pthreads_test/test2)
==23152==
==23152== LEAK SUMMARY:
==23152== definitely lost: 160,670 bytes in 12,000 blocks
==23152== indirectly lost: 0 bytes in 0 blocks
==23152== possibly lost: 152 bytes in 1 blocks
==23152== still reachable: 28 bytes in 1 blocks
==23152== suppressed: 0 bytes in 0 blocks
==23152== Reachable blocks (those to which a pointer was found) are not shown.
==23152== To see them, rerun with: --leak-check=full --show-reachable=yes
==23152==
==23152== For counts of detected and suppressed errors, rerun with: -v
==23152== ERROR SUMMARY: 8 errors from 8 contexts (suppressed: 36 from 8)
Here is the source code :
#include <iostream>
#include <cstdlib>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cstring>
#include <stdexcept>
using namespace std;
void file_put_contents(char* filename, char* content, char* mode)
{
char* filename2;
filename2 = strdup(filename);
char* content2;
content2 = strdup(content);
char* writemode = "a";
if(strstr(mode,"FILE_APPEND"))
{
writemode = "a";
}
else if(strstr(mode,"FILE_OVERWRITE"))
{
writemode = "w";
}
else
{
writemode = "w";
}
FILE * file;
file = fopen(filename2,writemode);
fprintf(file,content2);
fclose(file);
}
int NUM_THREADS = 2000;
int MAX_THREADS = 500;
int THREADSTACK = 65536;
struct thread_struct{
int arg1;
int arg2;
};
pthread_mutex_t mutex_;
pthread_mutex_t mutex2_;
static unsigned int thread_count = 0;
string exec(const char* cmd)
{
int DEBUG=0;
char buffer[5000];
string result = "";
FILE* pipe = popen(cmd, "r");
if (!pipe && DEBUG) throw runtime_error("popen() failed!");
try
{
while (!feof(pipe))
{
if (fgets(buffer, 128, pipe) != NULL)
{
result += buffer;
}
}
}
catch(...)
{
pclose(pipe);
throw;
}
pclose(pipe);
return result;
}
void *thread_test(void *arguments)
{
pthread_mutex_lock(&mutex_);
thread_count++;
pthread_mutex_unlock(&mutex_);
struct thread_struct *args = (thread_struct*)arguments;
int thread_id = (int) args->arg1;
char debug_var[100];
// UGLY DEBUG
memset(debug_var,0,sizeof(debug_var)); sprintf(debug_var,"BEGIN:%d:%d\n",thread_id,__LINE__); file_put_contents("debug.log",debug_var,"FILE_APPEND");
int random_sleep;
random_sleep = rand() % 10 + 3;
char command[100];
memset(command,0,sizeof(command));
sprintf(command,"sleep %d",random_sleep);
exec(command);
pthread_mutex_lock(&mutex_);
thread_count--;
pthread_mutex_unlock(&mutex_);
// UGLY DEBUG
memset(debug_var,0,sizeof(debug_var)); sprintf(debug_var,"END:%d:%d\n",thread_id,__LINE__); file_put_contents("debug.log",debug_var,"FILE_APPEND");
printf("THREAD [%d] ending\n",thread_id);
pthread_exit(NULL);
}
int main()
{
// pthread_t threads[NUM_THREADS];
int rc;
printf("Beginning ...");
usleep(1000000);
srand ((unsigned)time(NULL));
unsigned int thread_count_now = 0;
pthread_attr_t attrs;
pthread_attr_init(&attrs);
pthread_attr_setstacksize(&attrs, THREADSTACK);
pthread_attr_setdetachstate(&attrs, PTHREAD_CREATE_DETACHED);
pthread_mutex_init(&mutex2_, NULL);
for(int i=0; i < NUM_THREADS; i++ )
{
create_thread:
pthread_mutex_lock(&mutex_);
thread_count_now = thread_count;
pthread_mutex_unlock(&mutex_);
struct thread_struct struct1;
struct1.arg1 = i;
struct1.arg2 = 999;
pthread_t temp_thread;
printf("CREATE thread [%d]\n",i);
rc = pthread_create(&temp_thread, &attrs, &thread_test, (void *)&struct1);
char debug_var[100];
memset(debug_var,0,sizeof(debug_var)); sprintf(debug_var,"THREAD:%d:RC=%d:%d\n",i,rc,__LINE__); file_put_contents("debug.log",debug_var,"FILE_APPEND");
if (rc)
{
printf("Unable to create thread %d\n",rc);
sleep(1);
pthread_detach(temp_thread);
goto create_thread;
}
usleep(10);
while(true)
{
if(thread_count >= MAX_THREADS)
{
// printf("Thread POOL full %d of %d\n",thread_count,MAX_THREADS);
}
else
{
break;
}
usleep(10);
}
}
pthread_attr_destroy(&attrs);
pthread_mutex_destroy(&mutex2_);
printf("Proccess completed!\n");
pthread_exit(NULL);
return 1;
}
Did i forgot somewhere to free memory?
I don't quite understand those logs perfectly, can you give me any clue? What is wrong? What do i have to change?
Thank you.