hgweb: config option to control zlib compression level Before this patch, the HTTP transport protocol would always zlib compress certain responses (notably "getbundle" wire protocol commands) at zlib compression level 6. zlib can be a massive CPU resource sink for servers. Some server operators may wish to reduce server-side CPU requirements while requiring more bandwidth. This is common on corporate intranets, for example. Others may wish to use more CPU but reduce bandwidth. This patch introduces a config option to allow server operators to control the zlib compression level. On the "mozilla-unified" generaldelta repository, setting this value to "0" (disable compression) results in server-side CPU utilization for a `hg clone` going from ~180s to ~124s CPU time on my i7-6700K. A level of "1" (which increases the transfer size from ~1,074 MB at level 6 to ~1,222 MB) utilizes ~132s CPU time.

--- a/mercurial/hgweb/protocol.py	Sat Aug 06 17:04:22 2016 -0700
+++ b/mercurial/hgweb/protocol.py	Sun Aug 07 18:09:58 2016 -0700
@@ -74,7 +74,7 @@
         self.ui.ferr, self.ui.fout = self.oldio
         return val
     def groupchunks(self, cg):
-        z = zlib.compressobj()
+        z = zlib.compressobj(self.ui.configint('server', 'zliblevel', -1))
         while True:
             chunk = cg.read(4096)
             if not chunk: