A. Jesse Jiryu Davis added the comment: An Apple Developer Relations engineer tells me it's "reasonable to assume that getaddrinfo() is thread safe" on OS X 10.5 and later. (He mentioned that iOS inherited the OS X 10.5 DNS architecture, so Apple phones, watches, TVs, hairdryers, etc. can all do concurrent DNS too.)
Before OS X 10.5 the DNS system was a mix of new Mac OS X features, mDNSResponder and Open Directory, along with historical lookupd from NeXT and libresolv from an old BSD. In 10.5 the system was cleaned up to depend on OS X's mDNSResponder consistently; in the process getaddrinfo became thread-safe. He cites as further evidence of its thread safety: * The "bugs" section of getaddrinfo's man page was removed in 10.5 * 10.5 is the first OS X to be UNIX '03 certified, which includes the requirement that getaddrinfo be thread-safe * The system itself uses getaddrinfo extensively as if it's thread-safe * He hasn't seen reports of thread-safety problems with getaddrinfo He explained how the code works. In the latest version: http://www.opensource.apple.com/source/Libinfo/Libinfo-476/lookup.subproj/libinfo.c getaddrinfo calls down to libinfo’s "mdns" module: http://www.opensource.apple.com/source/Libinfo/Libinfo-476/lookup.subproj/mdns_module.c "mdns" uses the DNS-SD API declared in dns_sd.h, which he says is "well known to be thread safe." The DNS-SD API is part of the mDNSResponder project: http://www.opensource.apple.com/source/mDNSResponder/mDNSResponder-576.30.4/ The key function is DNSServiceQueryRecord: http://www.opensource.apple.com/source/mDNSResponder/mDNSResponder-576.30.4/mDNSShared/dnssd_clientstub.c My contact concludes, "As you can see, it does an IPC over to the mDNSResponder process, at which point thread safety is assured." ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue25924> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
