Gary

ReadImageBlob, 7M pdf (41 pages) covert to image, memory increase to 9G

yes, in a single call, but not after releasing the resources, just after ReadImageBlob(data). ImageMagick 7.1.0-0 Q16 x86_64 2021-06-13 imagick.v3 Mac 12.4

Yes, this is not a memory leak. I just can't find a solution in any other places :( Anyway, thanks for your reply.