chgserver: remove logic about appnope

Summary:
It turns out that initializing objc types before (disabling appnap) and after
(via libcurl [2]) fork() would abort the program like:

  objc[<pid>]: +[__NSCFConstantString initialize] may have been in progress in another thread when fork() was called.

It seems objc really dislikes fork. Disabling the objc logic before fork seems
to be the only way to unblock the issue.

Other approaches considered:
- Avoid `fork()`: not really fesiable for performance (startup, Python GIL) reasons.
- Ensure chgserver does not create threads (see https://bugs.python.org/issue33725).
  Not possible since appnope implicitly creates a (short-lived?) thread.
- Disable AppNap without using objc: does not seem trivial.
- Set `OBJC_DISABLE_INITIALIZE_FORK_SAFETY` to `YES`. Abort with a different
  message [1].

[1]:

```
The process has forked and you cannot use this CoreFoundation functionality safely. You MUST exec(). Break on __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__() to debug.
```

[2]:

```
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
  * frame #0: 0x00007ff81395f067 libobjc.A.dylib`objc_initializeAfterForkError
    frame #1: 0x00007ff81395f187 libobjc.A.dylib`performForkChildInitialize(objc_class*, objc_class*) + 274
    frame #2: 0x00007ff81394a479 libobjc.A.dylib`initializeNonMetaClass + 617
    frame #3: 0x00007ff813949f12 libobjc.A.dylib`initializeAndMaybeRelock(objc_class*, objc_object*, mutex_tt<false>&, bool) + 232
    frame #4: 0x00007ff813949c93 libobjc.A.dylib`lookUpImpOrForward + 1087
    frame #5: 0x00007ff81394e02f libobjc.A.dylib`object_getMethodImplementation + 153
    frame #6: 0x00007ff813b12934 CoreFoundation`_NSIsNSString + 55
    frame #7: 0x00007ff813b128dc CoreFoundation`-[NSTaggedPointerString isEqual:] + 36
    frame #8: 0x00007ff813b05609 CoreFoundation`CFEqual + 533
    frame #9: 0x00007ff813b0b2a3 CoreFoundation`_CFBundleCopyBundleURLForExecutableURL + 220
    frame #10: 0x00007ff813b069cb CoreFoundation`CFBundleGetMainBundle + 116
    frame #11: 0x00007ff813b28ade CoreFoundation`_CFPrefsGetCacheStringForBundleID + 71
    frame #12: 0x00007ff813b2f52f CoreFoundation`-[CFPrefsPlistSource setDomainIdentifier:] + 92
    frame #13: 0x00007ff813b2f46c CoreFoundation`-[CFPrefsPlistSource initWithDomain:user:byHost:containerPath:containingPreferences:] + 99
    frame #14: 0x00007ff813b2f351 CoreFoundation`__85-[_CFXPreferences(PlistSourceAdditions) withManagedSourceForIdentifier:user:perform:]_block_invoke + 156
    frame #15: 0x00007ff813c622a7 CoreFoundation`-[_CFXPreferences withSources:] + 60
    frame #16: 0x00007ff813cac80f CoreFoundation`-[_CFXPreferences withManagedSourceForIdentifier:user:perform:] + 240
    frame #17: 0x00007ff813b2a1ab CoreFoundation`-[CFPrefsSearchListSource addManagedSourceForIdentifier:user:] + 98
    frame #18: 0x00007ff813c83a18 CoreFoundation`__108-[_CFXPreferences(SearchListAdditions) withSearchListForIdentifier:container:cloudConfigurationURL:perform:]_block_invoke.160 + 287
    frame #19: 0x00007ff813c836e8 CoreFoundation`-[_CFXPreferences withSearchLists:] + 60
    frame #20: 0x00007ff813b29f50 CoreFoundation`__108-[_CFXPreferences(SearchListAdditions) withSearchListForIdentifier:container:cloudConfigurationURL:perform:]_block_invoke + 279
    frame #21: 0x00007ff813c83879 CoreFoundation`-[_CFXPreferences withSearchListForIdentifier:container:cloudConfigurationURL:perform:] + 374
    frame #22: 0x00007ff813b29a42 CoreFoundation`-[_CFXPreferences copyAppValueForKey:identifier:container:configurationURL:] + 137
    frame #23: 0x00007ff813b29978 CoreFoundation`_CFPreferencesCopyAppValueWithContainerAndConfiguration + 101
    frame #24: 0x00007ff8145c672b SystemConfiguration`SCDynamicStoreCopyProxiesWithOptions + 155
    frame #25: 0x000000010272a315 hg`Curl_resolv(data=0x00007f8dea888a00, hostname="api.github.com", port=443, allowDOH=true, entry=0x000000030a12be10) at hostip.c:675:30 [opt]
    frame #26: 0x000000010272a68c hg`Curl_resolv_timeout(data=<unavailable>, hostname=<unavailable>, port=<unavailable>, entry=<unavailable>, timeoutms=<unavailable>) at hostip.c:908:8 [opt] [artificial]
    frame #27: 0x0000000102753e1e hg`create_conn at url.c:3440:12 [opt]
    frame #28: 0x0000000102753cfe hg`create_conn(data=0x00007f8dea888a00, in_connect=0x000000030a12bed8, async=0x000000030a12bf8f) at url.c:4077:12 [opt]
    frame #29: 0x000000010275026b hg`Curl_connect(data=0x00007f8dea888a00, asyncp=0x000000030a12bf8f, protocol_done=0x000000030a12bfb2) at url.c:4156:12 [opt]
    frame #30: 0x000000010273dbd1 hg`multi_runsingle(multi=<unavailable>, nowp=0x000000030a12c020, data=0x00007f8dea888a00) at multi.c:1858:16 [opt]
    frame #31: 0x000000010273d6ae hg`curl_multi_perform(multi=0x00007f8deb0699c0, running_handles=0x000000030a12c074) at multi.c:2636:14 [opt]
    frame #32: 0x0000000102726ada hg`curl_easy_perform at easy.c:599:15 [opt]
    frame #33: 0x0000000102726aa8 hg`curl_easy_perform [inlined] easy_perform(data=0x00007f8dea888a00, events=false) at easy.c:689:42 [opt]
    frame #34: 0x00000001027269a4 hg`curl_easy_perform(data=0x00007f8dea888a00) at easy.c:708:10 [opt]
    frame #35: 0x00000001025e1cf6 hg`http_client::request::Request::send::h13a4e600f6bc5508 [inlined] curl::easy::handler::Easy2$LT$H$GT$::perform::h2ba0ae1da25a8852(self=<unavailable>) at handler.rs:3163:37 [opt]
```

Reviewed By: bolinfest

Differential Revision: D40538471

fbshipit-source-id: cd8611c8082fbe2d610efb78cb84defdb16d7980

eden/scm/edenscm/chgserver.py

@@ -379,16 +379,6 @@ def createcmdserver(self, repo, conn, fin, fout):
         return chgcmdserver(self.ui, repo, fin, fout, conn, self._baseaddress)
 
 
-def _disable_app_nap():
-    """disable AppNap on macOS.
-    AppNap might slow down the server to the point it's unusable.
-    """
-    if pycompat.isdarwin:
-        import appnope
-
-        appnope.nope()
-
-
 def chgunixservice(ui, repo, opts):
     # CHGINTERNALMARK is set by chg client. It is an indication of things are
     # started by chg so other code can do things accordingly, like disabling
@@ -402,5 +392,4 @@ def chgunixservice(ui, repo, opts):
         # one chgserver can serve multiple repos. drop repo information
         ui.setconfig("bundle", "mainreporoot", "", "repo")
     h = chgunixservicehandler(ui)
-    _disable_app_nap()
     return commandserver.unixforkingservice(ui, repo=None, opts=opts, handler=h)

eden/scm/setup.py

@@ -770,7 +770,6 @@ class fetchbuilddeps(Command):
             "https://files.pythonhosted.org/packages/39/7b/88dbb785881c28a102619d46423cb853b46dbccc70d3ac362d99773a78ce/pexpect-4.8.0-py2.py3-none-any.whl",
             "https://files.pythonhosted.org/packages/23/6a/210816c943c9aeeb29e4e18a298f14bf0e118fe222a23e13bfcc2d41b0a4/ipython-7.16.1-py3-none-any.whl",
             "https://files.pythonhosted.org/packages/3d/57/4d9c9e3ae9a255cd4e1106bb57e24056d3d0709fc01b2e3e345898e49d5b/simplegeneric-0.8.1.zip",
-            "https://files.pythonhosted.org/packages/41/4a/381783f26df413dde4c70c734163d88ca0550a1361cb74a1c68f47550619/appnope-0.1.3-py2.py3-none-any.whl",
             "https://files.pythonhosted.org/packages/44/6f/7120676b6d73228c96e17f1f794d8ab046fc910d781c8d151120c3f1569e/toml-0.10.2-py2.py3-none-any.whl",
             "https://files.pythonhosted.org/packages/44/98/5b86278fbbf250d239ae0ecb724f8572af1c91f4a11edf4d36a206189440/colorama-0.4.4-py2.py3-none-any.whl",
             "https://files.pythonhosted.org/packages/4c/1c/ff6546b6c12603d8dd1070aa3c3d273ad4c07f5771689a7b69a550e8c951/backcall-0.2.0-py2.py3-none-any.whl",