【讨论】malloc的可重入性和线程安全性

#include <stdlib.h> #include <stdio.h> #include <string.h> #include <sys/time.h> #include <signal.h> #include <pthread.h> #include <unistd.h> #define TRUE 1 #define FALSE 0 int GP[10]; int num = 10; pthread_mutex_t _mutex = PTHREAD_MUTEX_INITIALIZER; #define VMallocLightType( type, amount ) ( (type *)malloc( sizeof(type)*(amount) ) ) #define VFreeLightType( pointer ) ( free( pointer ) ) //统一起见 #define SleepMs( ms ) ( usleep( (ms)*1000 ) ) void doing( int ii ) { int *pp[100][100]; for( int i = 0; i < 100; ++i ) for( int j = 0; j < 100; ++j ) { pthread_mutex_lock( &_mutex ); pp[i][j] = VMallocLightType( int, num ); pthread_mutex_unlock( &_mutex ); pp[i][j][0] = GP[0]; } for( int i = 0; i < 100; ++i ) for( int j = 0; j < 100; ++j ) { pthread_mutex_lock( &_mutex ); VFreeLightType( pp[i][j] ); pthread_mutex_unlock( &_mutex ); } // ++num; printf( "[%d]:%p/n", ii, pp ); SleepMs( 1 ); } void *tFun0( void * ) { int a[1]; while(1) { doing(0); } } void *tFun1( void * ) { int a[1]; while(1) { doing(1); } } void *tFun2( void * ) { int a[1]; while(1) { doing(2); } } void *tFun3( void * ) { int a[1]; while(1) { doing(3); } } void *tFun4( void * ) { int a[1]; while(1) { doing(4); } } void *tFun5( void * ) { int a[1]; while(1) { doing(5); } } int createThread( pthread_t *thread, pthread_attr_t * attr, void *(*start_routine)(void *), void * arg ) { if ( pthread_create( thread, attr, start_routine, arg ) ) //成功则返回0 { } return TRUE; } void timeSignalFunc( int ) { int a[1]; doing(9); } void initSigaction() { struct sigaction act; act.sa_handler = timeSignalFunc; act.sa_flags = SA_RESTART; sigemptyset( &act.sa_mask ); sigaction( SIGALRM, &act, NULL ); } void initTime() { struct itimerval value; value.it_value.tv_sec = 0; value.it_value.tv_usec = 100 * 1000; value.it_interval = value.it_value; setitimer( ITIMER_REAL, &value, NULL ); } int main(int argc, char* argv[]) { scanf( "%d", &num ); printf( "glibc1:%p,glibc2:%p,glibc3:%p,heap1:%p,heap2:%p,heap3:%p,stack:%p,data:%p,code0:%p,code1:%p/n", printf, sigaction, pthread_mutex_lock, malloc(16), malloc(128), malloc(1024*1024),&argc, GP, main, initTime ); //glibc1:0x8654,glibc2:0x86a8,glibc3:0x86cc,heap1:0x111a0,heap2:0x111b8,heap3:0x40135008,stack:0xbffffd4c, //data:0x11060,code0:0x8cd0,code1:0x8c78 // initSigaction(); // initTime(); pthread_t touch_thread[6]; createThread( &touch_thread[0], NULL, tFun0, NULL ); createThread( &touch_thread[1], NULL, tFun1, NULL ); createThread( &touch_thread[2], NULL, tFun2, NULL ); createThread( &touch_thread[3], NULL, tFun3, NULL ); createThread( &touch_thread[4], NULL, tFun4, NULL ); createThread( &touch_thread[5], NULL, tFun5, NULL ); while( 1 ) { // num = num % 121; doing( 8 ); // printf( "main:%p/n", pp ); } return 0; }

//注1:定时函数与主线程函数共用堆栈
//注2:普通线程栈区的默认大小是2M,主线程栈区是8M
//注3:

//经测试:malloc非线程安全(在malloc,free操作很频繁时,会出错),加互斥量后,OK
/*
未加互斥量:
[5]:0xbedf6104
[0]:0xbf7f6104
[8]:0xbfff60f0
[4]:0xbeff6104
[2]:0xbf3f6104
[1]:0xbf5f6104
[3]:0xbf1f6104
[3]:0xbf1f6104
[5]:0xbedf6104
[0]:0xbf7f6104
[8]:0xbfff60f0
[2]:0xbf3f6104
[4]:0xbeff6104
[1]:0xbf5f6104
[3]:0xbf1f6104
[2]:0xbf3f6104
[8]:0xbfff60f0
[0]:0xbf7f6104
[1]:0xbf5f6104
[8]:0xbfff60f0
[4]:0xbeff6104
[2]:0xbf3f6104
[1]:0xbf5f6104
[0]:0xbf7f6104
[5]:0xbedf6104
Out of Memory: Killed process 185 (mmmm).
Out of Memory: Killed process 186 (mmmm).
Out of Memory: Killed process 187 (mmmm).
Out of Memory: Killed process 188 (mmmm).
Out of Memory: Killed process 189 (mmmm).
Out of Memory: Killed process 190 (mmmm).
Out of Memory: Killed process 191 (mmmm).
Out of Memory: Killed process 192 (mmmm).
Terminated
*/

//经测试:malloc也不可重入,定时函数重入主线程时,都会死掉。

//注:以上测试平台ARM_LINUX。