pigz decompress performance drops when overwriting file

[yukha-dw]

Hello, i have found interesting behaviour when using pigz. When pigz tries to overwrite file, it needs 500% more time to replace the file (or other operations, i'm not quite sure).

top is overwrite.

I also tried it on gzip, but it has no this interesting behaviour as intended.

[tansy]

I noticed that as well but didn't observe such a big difference. In my case it was about 1 second more when overwriting file with -f. It's not consistent either - sometimes it was not a case sometimes, more often than not, it was.

[madler]

I can't duplicate this:

% cp enwik8.gz xx.gz;cp enwik8.gz yy.gz;pigz -dk xx.gz;time pigz -df xx.gz;time pigz -df yy.gz
pigz -df xx.gz  0.30s user 0.04s system 113% cpu 0.302 total
pigz -df yy.gz  0.30s user 0.04s system 113% cpu 0.304 total

Closing.