Christian Heimes wrote:
Istvan Albert wrote:
A previous poster suggested that in this case the slowdown is caused
by the new io code being written in python rather than C.
For text mode Python 3's write() method is slower than Python 2.x's
method because all text is encoded. The slowdown is mostly caused by
additional code for line ending detection and decoding/encoding. The new
io library does more than the old file object
So far the new io library hasn't been optimized yet, too. Please give it
some time and report speed issues at http://bugs.python.org/.
On WinXP, tests 3 times each
-------------------------------------------
3.0
---
import time
line = 'a'*99 + '\n'
text = line*500000
start=time.time()
open('wtest', 'w').write(text)
print(time.time()-start)
# 3.4 to 4.0
import time
line = 'a'*99 + '\n'
text = line*500000
start=time.time()
text = bytes(line,'ascii')*500000
print(time.time()-start)
# 1.1 to 1.25
start=time.time()
open('wtest', 'wb').write(text) # note wb
print(time.time()-start)
# 1.5 to 1.8
----------------------------------------------
2.5
---
import time
line = 'a'*99 + '\n'
text = line*500000
start=time.time()
open('wtest', 'w').write(text)
print(time.time()-start)
# 3.3 to 4.1
import time
line = 'a'*99 + '\n'
text = line*500000
start=time.time()
open('wtest', 'wb').write(text) # note wb
print(time.time()-start)
# 1.0 to 1.6
-------------------------------------------------
Conclusion:
1. on WinXP, writing with 3.0 has no slowdown versus 2.5
2. on WinXP, binary mode writing is about 3 times faster that text mode
writing with its line-ending expansion. If that is not needed, binary
mode and explicit bytes-text conversion is about twice as fast.
Terry Jan Reedy
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