Eric Blake <ebb9 <at> byu.net> writes: > > else > > sprintf(cmd, "sh -c '%s' %d>&-", program, pdes[1]) > > } > > pid = spawnl(_P_NOWAIT, _PATH_BSHELL, "sh", "-c", cmd, NULL); > > Why are you going through two levels of sh? That seems like a waste to > me; the whole idea of using spawn is to avoid a fork(), but when you > invoke "sh" "-c" "sh -c 'cmd'", you are right back to a fork. True, the > new invocation of sh uses less memory than the 1 GB process that invoked > popen, so less thrashing will occur, but your whole approach seems > fundamentally flawed if you are trying to use spawn to avoid a fork.
You know, maybe a better approach to this would be to first implement posix_spawn() in cygwin, since that API seems like it would be possible to do the necessary fd manipulation in a spawned child process without the penalty of a full fork/exec. Then you could teach popen how to use posix_spawn when it is available, which is probably a patch more likely to be accepted in newlib, rather than your current idea of having to go through an intermediary sh invocation. But I do not have a copyright on file for cygwin contributions, so I am currently unable to work on contributing posix_spawn; you are at the mercy of someone willing and able to write such a patch. -- Eric Blake -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
