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Created on 2012-10-06 21:09 by nedbat, last changed 2022-04-11 14:57 by admin. This issue is now closed.
| Files | ||||
|---|---|---|---|---|
| File name | Uploaded | Description | Edit | |
| bug16152_v33.patch | nedbat, 2012-10-07 00:47 | Patch for 3.3 | review | |
| bug16152_v27.patch | nedbat, 2012-10-07 00:48 | Patch for 2.7 | review | |
| Pull Requests | |||
|---|---|---|---|
| URL | Status | Linked | Edit |
| PR 6572 | closed | lukasz.langa, 2018-04-23 01:09 | |
| Messages (8) | |||
|---|---|---|---|
| msg172244 - (view) | Author: Ned Batchelder (nedbat) *  |
Date: 2012-10-06 21:09 | |
When tokenizing with tokenize.generate_tokens, if the code ends with whitespace (no newline), the tokenizer produces an ERRORTOKEN for each space. Additionally, the regex that fails to find tokens in those spaces is linear in the number of spaces, so the overall performance is O(n**2).
I found this while tokenizing code samples uploaded to a public web site. One sample for some reason ended with 40,000 spaces, which was taking two hours to tokenize.
Demonstration:
{{{
import token
import tokenize
try:
from cStringIO import StringIO
except:
from io import StringIO
code = "@"+" "*10000
code_reader = StringIO(code).readline
for num, (ttyp, ttok, _, _, _) in enumerate(tokenize.generate_tokens(code_reader)):
print("%5d %15s %r" % (num, token.tok_name[ttyp], ttok))
}}}
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| msg172246 - (view) | Author: Ned Batchelder (nedbat) * |
Date: 2012-10-06 21:15 | |
Here's a patch for 3.3. I would like to also fix 2.7... |
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| msg172276 - (view) | Author: Ned Batchelder (nedbat) * |
Date: 2012-10-07 00:49 | |
Updated with new (better) patch, for v2.7 and v3.3. They are the same except for the test. |
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| msg172546 - (view) | Author: Jesús Cea Avión (jcea) *  |
Date: 2012-10-10 01:04 | |
Ned, could you possibly send a Contributor Form Agreement? http://www.python.org/psf/contrib/ |
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| msg172548 - (view) | Author: Ned Batchelder (nedbat) * |
Date: 2012-10-10 02:05 | |
Jesús, done! |
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| msg174640 - (view) | Author: Roundup Robot (python-dev) |
Date: 2012-11-03 15:51 | |
New changeset eb7ea51e658e by Ezio Melotti in branch '2.7': #16152: fix tokenize to ignore whitespace at the end of the code when no newline is found. Patch by Ned Batchelder. http://hg.python.org/cpython/rev/eb7ea51e658e New changeset 3ffff1798ed5 by Ezio Melotti in branch '3.2': #16152: fix tokenize to ignore whitespace at the end of the code when no newline is found. Patch by Ned Batchelder. http://hg.python.org/cpython/rev/3ffff1798ed5 New changeset 1fdeddabddda by Ezio Melotti in branch '3.3': #16152: merge with 3.2. http://hg.python.org/cpython/rev/1fdeddabddda New changeset ed091424f230 by Ezio Melotti in branch 'default': #16152: merge with 3.3. http://hg.python.org/cpython/rev/ed091424f230 |
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| msg174641 - (view) | Author: Ezio Melotti (ezio.melotti) * |
Date: 2012-11-03 15:53 | |
Fixed, thanks for the report and the patch! |
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| msg315641 - (view) | Author: Ned Batchelder (nedbat) * |
Date: 2018-04-23 01:26 | |
PR 6273 is mentioned, but I think 6573 is the correct number. |
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