我刚才注意到当我使用pthread_create()生成一个线程时,我为线程设置自定义堆栈大小的请求似乎被忽略了。特别是,如果我从生成的线程中调用pthread_attr_getstacksize(),它总是会报告默认的堆栈大小,而不管我要求的是什么。
在Linux和MacOS / X下都可以看到这种行为,所以我怀疑我做错了什么,但我不知道它是什么。
要重现该问题,请编译并运行以下代码(通过“g ++ stack_test.cpp -lpthread; ./a.out”)。它会尝试一堆不同的堆栈大小并抱怨它的请求不受尊重。有问题的输出如下所示:
Jeremys-Mini:~ lcsuser1$ ./a.out
Testing creation of a thread with stack size: 8192
ThreadFunc: ERROR, wrong stack size! (Requested: 8192, got: 524288)
Testing creation of a thread with stack size: 16384
ThreadFunc: ERROR, wrong stack size! (Requested: 16384, got: 524288)
Testing creation of a thread with stack size: 24576
ThreadFunc: ERROR, wrong stack size! (Requested: 24576, got: 524288)
[...]
Testing creation of a thread with stack size: 8372224
ThreadFunc: ERROR, wrong stack size! (Requested: 8372224, got: 524288)
Testing creation of a thread with stack size: 8380416
ThreadFunc: ERROR, wrong stack size! (Requested: 8380416, got: 524288)
......这是代码:
#include <stdio.h>
#include <pthread.h>
static void * ThreadFunc(void * pDesiredStackSize)
{
const size_t desiredStackSize = *((size_t *)pDesiredStackSize);
pthread_attr_t tattr;
if (pthread_attr_init(&tattr) == 0)
{
size_t actualStackSize;
if (pthread_attr_getstacksize(&tattr, &actualStackSize) == 0)
{
if (actualStackSize == desiredStackSize)
{
printf("ThreadFunc: Stack size is as expected: %zu\n", actualStackSize);
}
else
{
printf("ThreadFunc: ERROR, wrong stack size! (Requested: %zu, got: %zu)\n", desiredStackSize, actualStackSize);
}
}
else perror("pthread_attr_getstacksize");
}
else perror("pthread_attr_init(2)");
return NULL;
}
static void TestCustomStackSize(size_t desiredStackSizeBytes)
{
printf("Testing creation of a thread with stack size: %zu\n", desiredStackSizeBytes);
pthread_attr_t attr;
if (pthread_attr_init(&attr) != 0)
{
perror("pthread_attr_init");
return;
}
int r = pthread_attr_setstacksize(&attr, desiredStackSizeBytes);
if (r == 0)
{
pthread_t thread;
if (pthread_create(&thread, &attr, ThreadFunc, &desiredStackSizeBytes) == 0)
{
if (pthread_join(thread, NULL) != 0) perror("pthread_join");
}
else perror("pthread_create");
}
else
{
perror("pthread_attr_setstacksize");
printf("pthread_attr_setstacksize returned %i\n", r);
}
}
int main(int argv, char ** argc)
{
const int PAGE_SIZE=8*1024;
for (size_t stackSizePages=1; stackSizePages<1024; stackSizePages++) TestCustomStackSize(stackSizePages*PAGE_SIZE);
printf("Done!\n");
return 0;
}
答案 0 :(得分:2)
问题是tattr
没有引用当前线程的属性。它只是初始化为一个全新的属性,而pthread_attr_getstacksize()
返回给定属性中设置的给定堆栈大小,即传递给它的属性。
因此,如果您将正确的属性传递给pthread_attr_getstacksize()
,它应该可以正常工作。
呼叫
pthread_getattr_np(pthread_self(), &tattr);
前
if (pthread_attr_getstacksize(&tattr, &actualStackSize) == 0)
而不是初始化tattr
。
注意pthread_getattr_np()
是非标准函数(不在POSIX中)。