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GIF seek performance improvements #6077
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Just tested it out... great! Can't wait till it's released 😃. |
|
Is there any possibility these improvements will be included in release 9.1.0? Got a project that depends largely on it. |
I would consider it likely, yes. |
Ok. Thanks. |
Is the performance improvement quantifiable? |
Running tests from #6075 with iss634.gif,
from PIL import Image
import timeit
def test_is_animated_2():
img = Image.open("iss634.gif")
img.seek(41)
img.is_animated
print(timeit.timeit(stmt=test_is_animated_2, number=25)) Before This Commit: 0.991317542
from PIL import Image
import timeit
def test_seek_2():
with Image.open("iss634.gif") as im:
im.seek(41)
try:
im.seek(42)
except EOFError:
pass
print(timeit.timeit(stmt=test_seek_2, number=25)) Before This Commit: 0.9614665830000001
from PIL import Image
import timeit
def test_is_animated_n_frames():
img = Image.open("iss634.gif")
img.is_animated
img.n_frames
print(timeit.timeit(stmt=test_is_animated_n_frames, number=25)) Before This Commit: 0.527664791 |
For what it's worth, here is the large GIF i mentioned earlier. |
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I looked it over and I don't see any other quick and significant wins. There is one small thing where instead of reading the data of the current block and discarding it, we could seek instead, but this only affects slow file systems, so not sure if it's worth the added complexity:
--- a/src/PIL/GifImagePlugin.py
+++ b/src/PIL/GifImagePlugin.py
@@ -55,11 +55,15 @@ class GifImageFile(ImageFile.ImageFile):
global_palette = None
- def data(self):
+ def data(self, read_data=True):
s = self.fp.read(1)
- if s and s[0]:
+ if not read_data and s and s[0]:
+ self.fp.seek(s[0], 1)
+ return b""
+ elif s and s[0]:
return self.fp.read(s[0])
- return None
+ else:
+ return None
def _open(self):
@@ -100,7 +104,7 @@ class GifImageFile(ImageFile.ImageFile):
self._seek(self.tell() + 1, False)
except EOFError:
self._n_frames = self.tell() + 1
- self.seek(current)
+ self._seek(current, False)
return self._n_frames
@property
@@ -159,7 +163,7 @@ class GifImageFile(ImageFile.ImageFile):
if self.__offset:
# backup to last frame
self.fp.seek(self.__offset)
- while self.data():
+ while self.data(read_data=False) is not None:
pass
self.__offset = 0
@@ -243,7 +247,7 @@ class GifImageFile(ImageFile.ImageFile):
block = self.data()
if len(block) >= 3 and block[0] == 1:
info["loop"] = i16(block, 1)
- while self.data():
+ while self.data(read_data=False) is not None:
pass
elif s == b",":
Otherwise the PR looks good to me 👍
Note that merging this will close: #6105
Thanks for the approval, but yeah - testing your diff with runs of 1000 loops, I don't see any consistent improvements, so I'm not personally inclined. You do mention slow filesystems though, and I wouldn't describe my machine like that. |
Just curious, is there anything hindering these changes from being merged? 🤔 |
There are no problems that I'm aware of, no. Just waiting for another Pillow core developer to give their seal of approval. Judging from the past habits, I expect this, or a version of this, to be merged by the next release on April 1. If you need these changes sooner, you can always compile https://github.com/radarhere/Pillow/tree/gif from source yourself. |
Okay, I guessed as much.
Done that (for myself) since but the issue is... I'm concerned about the users of my project as Pillow is a core dependency and the issue concerned here affects performance and therefore user experience. For some insight, AnonymouX47/term-image#10 was the cause of these changes. Thanks. |
- Change: `ImageIterator` now uses image file size instead of frame count. NOTE: This change is temporary and will be reverted as soon as a Pillow version including the improvements in python-pillow/Pillow#6077 is released.
- Change: `ImageIterator` no longer uses frame count to determine frame caching status. - This is due to the bad performance of `PIL.GifImagePlugin.GifImageFile.nframes` with large (high frame-count) GIFs. NOTE: This change is temporary and will be reverted as soon as a Pillow version including the improvements in python-pillow/Pillow#6077 is released.
- Change: Caching of animated image frames in the TUI is now based on image file size instead of frame count. NOTE: This change is temporary and will be reverted as soon as a Pillow version including the improvements in python-pillow/Pillow#6077 is released.
- Change: Caching of animated image frames in the TUI is now based on image file size instead of frame count. - Adresses #10. NOTE: This change is temporary and will be reverted as soon as a Pillow version including the improvements in python-pillow/Pillow#6077 is released.
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There are no problems that I'm aware of, no. Just waiting for another Pillow core developer to give their seal of approval. Judging from the past habits, I expect this, or a version of this, to be merged by the next release on April 1.
🦭 of ✅!
Yep, this will be in 9.1.0 on April 1.
Resolves #6105
Pillow/src/PIL/GifImagePlugin.py
Lines 106 to 121 in 54be93c
Except it might be the case that the user has already seeked forward.
current
might be greater than 1. If so, then Pillow doesn't need to seek anywhere - we already know the image is animated.This PR uses that knowledge as a minor performance improvement.
_seek
updates the frame position, applies disposal to the previous frame, and then checks to see if there's any more data in the file.This PR rearranges that order, so if there is no more data, the image can stay as it is.
is_animated
andn_frames
seek forward through the GIF image to determine information about how many frames are present. During those seeks, the actual images are irrelevant. So don't perform image operations like loading or making sure that transparency and disposal are applied