error: message type 0x5a arrived from server while idle

hi all:

i use Python and PyGreSQL to link PostgreSQL
but the Python give me the error

the error here :
--------------------------------------------
...
95
93
95
97
94
96
94
message type 0x43 arrived from server while idle
message type 0x5a arrived from server while idle
INSERT INTO code (stock_name ,stock_code)values('bbbbb','bbbbb')

95
93
92
93
99
--------------------------------------------

and the PostgreSQL log error like here

-------------------------------------------
...
LOG: unexpected EOF on client connection
...
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me python code_me.py

--------------------------------------------
#!/usr/bin/env python
#coding=utf-8
import _pg
import threading

con =
_pg.connect(host='127.0.0.1',user='work',dbname='work',passwd='123',port=5432)

def link_url():
global con
for i in range(100):
print i
stock_sql = "INSERT INTO code (stock_name
,stock_code)values('bbbbb','bbbbb')"
try:
con.query(stock_sql)
except:
print stock_sql

if __name__=='__main__':
for i in range(0,32):
print i
i = threading.Thread(target = link_url)
i.start()

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who can help me ? thanks