diff mercurial/utils/compression.py @ 46789:471cd86c8eb4

bundle: optional multithreaded compression, ATM zstd-only

Compression type can be a huge chunk of "hg bundle", especially when
using the higher compression levels. With level=22 and threads=7, the
NetBSD test repository took 28:39 wall time and 157:47 user time.
Before, level=22 would take 129:20 wall time and 129:07 user time.

Differential Revision: https://phab.mercurial-scm.org/D9283

--- a/mercurial/utils/compression.py	Sat Mar 13 08:59:03 2021 +0100
+++ b/mercurial/utils/compression.py	Sun Nov 08 20:17:09 2020 +0100
@@ -685,9 +685,11 @@
         # while providing no worse compression. It strikes a good balance
         # between speed and compression.
         level = opts.get(b'level', 3)
+        # default to single-threaded compression
+        threads = opts.get(b'threads', 0)
 
         zstd = self._module
-        z = zstd.ZstdCompressor(level=level).compressobj()
+        z = zstd.ZstdCompressor(level=level, threads=threads).compressobj()
         for chunk in it:
             data = z.compress(chunk)
             if data: