多线程死机问题(与gc有关)

发布于 2018-12-28 10:20:46 浏览：2438 订阅该版

* 本帖最后由 hxcnz 于 2018-12-28 10:38 编辑 *

RT-Thread MicroPython 堆设了40k左右，单While循环长时间运行都正常，把 _thread 模块加入之后，运行几十秒就死机了(这时候比MicroPython优先级高的进程还能正常运行，说明RT-Thread系统没有死机)，代码如下：```import time
import _thread
import gc

def Test():
    while True:
        time.sleep_ms(10)
_thread.start_new_thread(Test, ())

cnt = 0
a0 = 10.5
a1 = 1.1
a2 = 2.2
a3 = 3.3
a4 = 4.4
a5 = 5.5
a6 = 6.6
a7 = 7.6

while True:
    cnt += 1
    a0 += 1
    a1 += 1
    a2 += 1
    a3 += 1
    a4 += 1
    a5 += 1
    a6 += 1
    a7 += 1
    print("While cnt:",cnt)
    print(
        "%f" % (a0),
        "%f" % (a1),
        "%f" % (a2),
        "%f" % (a3),
        "%f" % (a4),
        "%f" % (a5),
        "%f" % (a6),
        "%f" % (a7),
    )
    time.sleep_ms(100)```输出结果为：
 \ | /
- RT -     Thread Operating System
 / | \     4.0.0 build Dec 28 2018
 2006 - 2018 Copyright by rt-thread team
msh />ROM file system initializated!
TF_Card initialized!
msh />While cnt: 1
11.500000 2.100000 3.200000 4.300000 5.400000 6.500000 7.600000 8.600000
While cnt: 2
12.500000 3.100000 4.200000 5.300000 6.400000 7.500000 8.600000 9.600000
While cnt: 3
13.500000 4.100000 5.200000 6.300000 7.400000 8.500000 9.600000 10.600000
***此处省略n行***
While cnt: 150
160.500000 151.100000 152.200000 153.300000 154.400000 155.500000 156.600000 157.600000
While cnt: 151
161.500000 152.100000 153.200000 154.300000 155.400000 156.500000 157.600000 158.600000
While cnt: 152

在这里就卡死了，后来用 gc.mem_free() 查看剩余内存：

```import time
import _thread
import gc

def mem():
    r = gc.mem_free()
    print("free memory:", r)

def Test():
    while True:
        time.sleep_ms(10)
_thread.start_new_thread(Test, ())

cnt = 0
a0 = 10.5
a1 = 1.1
a2 = 2.2
a3 = 3.3
a4 = 4.4
a5 = 5.5
a6 = 6.6
a7 = 7.6

while True:
    cnt += 1
    a0 += 1
    a1 += 1
    a2 += 1
    a3 += 1
    a4 += 1
    a5 += 1
    a6 += 1
    a7 += 1
    print("While cnt:",cnt)
    print(
        "%f" % (a0),
        "%f" % (a1),
        "%f" % (a2),
        "%f" % (a3),
        "%f" % (a4),
        "%f" % (a5),
        "%f" % (a6),
        "%f" % (a7),
    )
    mem()
    time.sleep_ms(100)```输出结果如下：

***上面省略n行***
free memory: 1632
While cnt: 151
161.500000 152.100000 153.200000 154.300000 155.400000 156.500000 157.600000 158.600000
free memory: 1200
While cnt: 152
162.500000 153.100000 154.200000 155.300000 156.400000 157.500000 158.600000 159.600000
free memory: 768
While cnt: 153
163.500000 154.100000 155.200000 156.300000 157.400000 158.500000 159.600000 160.600000
free memory: 336
While cnt: 154

可看出剩余内存剩余不多了，这时候Python系统应该是自动执行gc.collect()的时候死机了，分析完整打印数据看出，在死机之前，已经经历了2~3次gc.collect()了。
注：在单线程运行的时候，free memory 在400的时候会执行一次gc，大概20s执行一次，连续运行7、8个小时都不会出问题。

接着增加手动gc试下：
```import time
import _thread
import gc

def mem():
    r = gc.mem_free()
    print("free memory:", r)

def Test():
    while True:
        time.sleep_ms(10)
_thread.start_new_thread(Test, ())

cnt = 0
a0 = 10.5
a1 = 1.1
a2 = 2.2
a3 = 3.3
a4 = 4.4
a5 = 5.5
a6 = 6.6
a7 = 7.6

while True:
    cnt += 1
    a0 += 1
    a1 += 1
    a2 += 1
    a3 += 1
    a4 += 1
    a5 += 1
    a6 += 1
    a7 += 1
    print("While cnt:",cnt)
    print(
        "%f" % (a0),
        "%f" % (a1),
        "%f" % (a2),
        "%f" % (a3),
        "%f" % (a4),
        "%f" % (a5),
        "%f" % (a6),
        "%f" % (a7),
    )
    gc.collect()
    mem()
    time.sleep_ms(100)```输出结果如下：
 \ | /
- RT -     Thread Operating System
 / | \     4.0.0 build Dec 28 2018
 2006 - 2018 Copyright by rt-thread team
msh />ROM file system initializated!
TF_Card initialized!
msh />While cnt: 1
11.500000 2.100000 3.200000 4.300000 5.400000 6.500000 7.600000 8.600000
free memory: 33024
While cnt: 2
12.500000 3.100000 4.200000 5.300000 6.400000 7.500000 8.600000 9.600000

在这里就卡死了，手动gc活不过3集{:3_45:}，求大神分析下什么原因，要怎样才能解决问题？难不成多线程用不了么？

后来将 gc.collect()改为：
if gc.mem_free() < 10000:
    gc.collect()
在执行2次gc.collect()后，还是死机了，感觉有多线程的情况下，不管手动gc还是自动gc，gc.collect()第三次就会死机。