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Author ronaldoussoren
Recipients gregory.p.smith, pablogsal, ronaldoussoren, serhiy.storchaka, vstinner
Date 2018-09-18.19:57:24
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Message-id <>
I did some more research:

* <> seems to indicate that glibc switched to a different implementation of posix_spawn that uses clone(2) instead of fork()/vfork() to avoid some problems with vfork(). 

The start of the issue also contains some information on why glibc is (was?) so conservative about using vfork, and a possible work around (disable cancelation points around the call to posix_spawn).

* <> is the source for the guts of posix_spawn for some version of glibc, and that indeed does use clone(...|CLONE_VFORK...) unconditionally and does not appear to test for POSIX_SPAWN_USEVFORK. 

It looks like the advise to use POSIX_SPAWN_USEVFORK is outdated, although I'm not 100% sure of my conclusion.  A glibc expert should be able to confirm or refute this. 

@pablogsal: do you have more information on why you want to enable this flag? Do you have measurements that show that adding this flag helps?
Date User Action Args
2018-09-18 19:57:24ronaldoussorensetrecipients: + ronaldoussoren, gregory.p.smith, vstinner, serhiy.storchaka, pablogsal
2018-09-18 19:57:24ronaldoussorensetmessageid: <>
2018-09-18 19:57:24ronaldoussorenlinkissue34663 messages
2018-09-18 19:57:24ronaldoussorencreate