changegroup: store old heads as a set Previously, the "oldheads" variable was a list. On a repository at Mozilla with 46,492 heads, profiling revealed that list membership testing was dominating execution time of applying small changegroups. This patch converts the list of old heads to a set. This makes membership testing significantly faster. On the aforementioned repository with 46,492 heads: $ hg unbundle <file with 1 changeset> before: 18.535s wall after: 1.303s Consumers of this variable only check for truthiness (`if oldheads`), length (`len(oldheads)`), and (most importantly) item membership (`h not in oldheads` - which occurs twice). So, the change to a set should be safe and suitable for stable. The practical effect of this change is that changegroup application and related operations (like `hg push`) no longer exhibit an O(n^2) CPU explosion as the number of heads grows.

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# An example WSGI for use with mod_wsgi, edit as necessary

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# See https://mercurial-scm.org/wiki/modwsgi for more information

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# Path to repo or hgweb config to serve (see 'hg help hgweb')

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config = "/path/to/repo/or/config"

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# Uncomment and adjust if Mercurial is not installed system-wide

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# (consult "installed modules" path from 'hg debuginstall'):

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#import sys; sys.path.insert(0, "/path/to/python/lib")

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# Uncomment to send python tracebacks to the browser if an error occurs:

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#import cgitb; cgitb.enable()

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# enable demandloading to reduce startup time

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from mercurial import demandimport; demandimport.enable()

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from mercurial.hgweb import hgweb

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application = hgweb(config)