worker: make waitforworkers reentrant
We are going to use it in the SIGCHLD handler. The handler will be executed
in the main thread with the non-blocking version of waitpid, while the
waitforworkers thread runs the blocking version. It's possible that one of
them collects a worker and makes the other error out (no child to wait).
This patch handles these errors: ECHILD is ignored. EINTR needs a retry.
The "pids" set is designed to be only modifiable by "waitforworkers". And we
only remove items after a successful waitpid. Since a child process can only
be "waitpid"-ed once. It's guaranteed that "pids.remove(p)" won't be called
with duplicated "p"s. And once a "p" is removed from "pids", that "p" does
not need to be killed or waited any more.
#!/usr/bin/env python
#
# An example hgweb CGI script, edit as necessary
# See also https://mercurial-scm.org/wiki/PublishingRepositories
# Path to repo or hgweb config to serve (see 'hg help hgweb')
config = "/path/to/repo/or/config"
# Uncomment and adjust if Mercurial is not installed system-wide
# (consult "installed modules" path from 'hg debuginstall'):
#import sys; sys.path.insert(0, "/path/to/python/lib")
# Uncomment to send python tracebacks to the browser if an error occurs:
#import cgitb; cgitb.enable()
from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb import hgweb, wsgicgi
application = hgweb(config)
wsgicgi.launch(application)