mirror of
https://github.com/psycopg/psycopg2.git
synced 2024-11-27 03:13:43 +03:00
62 lines
1.9 KiB
Python
62 lines
1.9 KiB
Python
import psycopg2, psycopg2.extensions
|
|
import threading
|
|
import gc
|
|
import time
|
|
import sys
|
|
|
|
# inherit psycopg2 connection class just so that
|
|
# garbage collector enters the tp_clear code path
|
|
# in delete_garbage()
|
|
|
|
class my_connection(psycopg2.extensions.connection):
|
|
pass
|
|
|
|
class db_user(threading.Thread):
|
|
def run(self):
|
|
conn2 = psycopg2.connect(sys.argv[1], connection_factory=my_connection)
|
|
cursor = conn2.cursor()
|
|
cursor.execute("UPDATE test_psycopg2_dealloc SET a = 3", async=1)
|
|
|
|
# the conn2 desctructor will block indefinitely
|
|
# on the completion of the query
|
|
# (and it will not be holding the GIL during that time)
|
|
print >> sys.stderr, "begin conn2 del"
|
|
del cursor, conn2
|
|
print >> sys.stderr, "end conn2 del"
|
|
|
|
def main():
|
|
# lock out a db row
|
|
conn1 = psycopg2.connect(sys.argv[1], connection_factory=my_connection)
|
|
cursor = conn1.cursor()
|
|
cursor.execute("DROP TABLE IF EXISTS test_psycopg2_dealloc")
|
|
cursor.execute("CREATE TABLE test_psycopg2_dealloc (a int)")
|
|
cursor.execute("INSERT INTO test_psycopg2_dealloc VALUES (1)")
|
|
conn1.commit()
|
|
cursor.execute("UPDATE test_psycopg2_dealloc SET a = 2", async=1)
|
|
|
|
# concurrent thread trying to access the locked row
|
|
db_user().start()
|
|
|
|
# eventually, a gc.collect run will happen
|
|
# while the conn2 is inside conn_close()
|
|
# but this second dealloc won't get blocked
|
|
# as it will avoid conn_close()
|
|
for i in range(10):
|
|
if gc.collect():
|
|
print >> sys.stderr, "garbage collection done"
|
|
break
|
|
time.sleep(1)
|
|
|
|
# we now unlock the row by invoking
|
|
# the desctructor of conn1. This will permit the
|
|
# concurrent thread destructor of conn2 to
|
|
# continue and it will end up trying to free
|
|
# self->dsn a second time.
|
|
print >> sys.stderr, "begin conn1 del"
|
|
del cursor, conn1
|
|
print >> sys.stderr, "end conn1 del"
|
|
|
|
|
|
if __name__ == '__main__':
|
|
main()
|