Mastodonでgifアイコンをconvertするときにメモリを激しく消費する。
120x120、1フレームのgifアイコンをconvertするときのメモリ消費
$ identify 1frame.gif
#> 1frame.gif GIF 120x120 120x120+0+0 8-bit sRGB 256c 13041B 0.000u 0:00.000--------------------------------------------------------------------------------
Command: convert -coalesce -auto-orient -resize 120x -crop 120x120+0+0 +repage -layers optimize -quality 80 -strip 1frame.gif out.gif
Massif arguments: (none)
ms_print arguments: massif.out.12017
--------------------------------------------------------------------------------
MB
128.8^ :
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0 +----------------------------------------------------------------------->Mi
0 73.42
〜中略〜
--------------------------------------------------------------------------------
n time(i) total(B) useful-heap(B) extra-heap(B) stacks(B)
--------------------------------------------------------------------------------
40 46,906,638 134,951,144 134,919,211 31,933 0
41 60,039,960 134,951,352 134,919,363 31,989 0
99.98% (134,919,363B) (heap allocation functions) malloc/new/new[], --alloc-fns, etc.
->99.50% (134,279,680B) 0x4F69C33: AcquireAlignedMemory (memory.c:262)
| ->99.46% (134,217,728B) 0x4F6A05B: AcquireVirtualMemory (memory.c:635)
| | ->99.46% (134,217,728B) 0x4F9C703: GetCubeInfo (quantize.c:2038)
| | ->99.46% (134,217,728B) 0x4F9C954: QuantizeImage (quantize.c:2699)
| | ->99.46% (134,217,728B) 0x558157A: MogrifyImageList (mogrify.c:8408)
| | ->99.46% (134,217,728B) 0x5582074: MogrifyImages (mogrify.c:8952)
| | ->99.46% (134,217,728B) 0x550B5FA: ConvertImageCommand (convert.c:3273)
| | ->99.46% (134,217,728B) 0x5576B8A: MagickCommandGenesis (mogrify.c:183)
| | ->99.46% (134,217,728B) 0x4011F9: MagickMain (magick.c:149)
| | ->99.46% (134,217,728B) 0x581F82E: (below main) (libc-start.c:291)
何が起きているんだ🤔
media_attachmentに同じ画像を投げたときのメモリ消費
--------------------------------------------------------------------------------
Command: ffmpeg -i 1frame.gif -c:a none -strict experimental -movflags faststart -pix_fmt yuv420p -vf scale=trunc(iw/2)*2:trunc(ih/2)*2 -vsync cfr -b:v 1300K -maxrate 500K -bufsize 1300K -crf 18 -y out.mp4
Massif arguments: --massif-out-file=gifv.out
ms_print arguments: gifv.out
--------------------------------------------------------------------------------
MB
7.944^ #
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0 +----------------------------------------------------------------------->Mi
0 111.8
GIF allocates 128MB of memory to dither - ImageMagick
CacheShiftを3に固定してみたらメモリ消費が激減した。
ImageMagick/quantize.c at master · ImageMagick/ImageMagick
CacheShiftの値は、macOS, iOS上だと3で、その他の環境だと2になるようだ。
サーバーと、手元のMacで全然メモリ消費が違ったのはこのせいらしい。