python3執行緒加鎖的乙個例子

再這個例子中，執行緒加上鎖之後有並行變成了實際上的序列

[root@linux1 python_tidb]# cat mypy02.py
#!/usr/bin/env python3
import pymysql,sys,os
import _thread,time
def counter(myid,count):
mutex.acquire()
for i in range(count):
time.sleep(1)
#mutex.acquire()
print("%s=>%s" % (myid,i))
#mutex.release()
mutex.release()
mutex = _thread.allocate_lock()
def parent():
for i in range(5):
myid = 'myid'+str(i)
_thread.start_new_thread(counter,(myid,5,))
parent()
time.sleep(30)
[root@linux1 python_tidb]# ./mypy02.py
myid3=>0
myid3=>1
myid3=>2
myid3=>3
myid3=>4
myid4=>0
myid4=>1
myid4=>2
myid4=>3
myid4=>4
myid2=>0
myid2=>1
myid2=>2
myid2=>3
myid2=>4
myid1=>0
myid1=>1
myid1=>2
myid1=>3
myid1=>4
myid0=>0
myid0=>1
myid0=>2
myid0=>3
myid0=>4
[root@linux1 python_tidb]#

[root@linux1 python_tidb]# cat mypy02.py

#!/usr/bin/env python3
import pymysql,sys,os
import _thread,time,random
int1 = 0
def add_int1(myid,count):
#mutex.acquire()
global int1
for i in range(count):
time.sleep(random.random())
if((i % 10)==0):
print("%s=>%s" %(myid,int1))
mutex.acquire()
int1 += 1
mutex.release()
#mutex.release()
mutex = _thread.allocate_lock()
def parent():
for i in range(500):
myid = 'myid'+str(i)
_thread.start_new_thread(add_int1,(myid,100,))
parent()
time.sleep(100)
print("int1:: %s" %(int1))

如果不在函式裡加這句 global int1，則會出現下面的錯誤

unhandled exception in thread started by traceback (most recent call last):
file "./mypy02.py", line 14, in add_int1
int1 += 1
unboundlocalerror: local variable 'int1' referenced before assignment
另外乙個我發現如果不讓執行緒隨機休眠time.sleep(random.random())，則很容易出現大家都在等待鎖，而無法進行下去
我懷疑釋放操作是不是和獲取操作也互斥呢
最開始是 time.sleep(1)所有執行緒都sleep一秒的時候程式根本就進行不下去，誰也獲得不了鎖
併發申請鎖是個問題

[root@linux1 python_tidb]# cat mypy02.py

#!/usr/bin/env python3
import pymysql,sys,os
import _thread,time,random
int1 = 0
def add_int1(myid,count):
#mutex.acquire()
global int1
for i in range(count):
time.sleep(random.random())
if((i % 10)==0):
print("%s=>%s" %(myid,int1))
mutex.acquire()
int1 += 1
mutex.release()
#mutex.release()
exit_mutexs[myid].release()
mutex = _thread.allocate_lock()
exit_mutexs =[_thread.allocate_lock() for i in range(500)]
for exit_mutex in exit_mutexs:
exit_mutex.acquire()
def parent():
for i in range(500):
#myid = 'myid'+str(i)
_thread.start_new_thread(add_int1,(i,100,))
parent()
for exit_mutex in exit_mutexs:
while exit_mutex.locked():pass
print("int1:: %s" %(int1))

[root@linux1 python_tidb]# cat mypy02.py

#!/usr/bin/env python3
import pymysql,sys,os
import _thread,time,random
int1 = 0
def add_int1(myid,count):
#mutex.acquire()
global int1
for i in range(count):
time.sleep(random.random())
if((i % 10)==0):
print("%s=>%s" %(myid,int1))
mutex.acquire()
int1 += 1
mutex.release()
#mutex.release()
exit_status[myid]=true
mutex = _thread.allocate_lock()
#exit_mutexs =[_thread.allocate_lock() for i in range(500)]
#for exit_mutex in exit_mutexs:
# exit_mutex.acquire()
exit_status = [false] * 500
def parent():
for i in range(500):
#myid = 'myid'+str(i)
_thread.start_new_thread(add_int1,(i,100,))
parent()
#for exit_mutex in exit_mutexs:
# while exit_mutex.locked():pass
while false in exit_status:pass
print("int1:: %s" %(int1))

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