From: root
If you don't know what event loop to use, use the one returned from this function.
The flags argument can be used to specify special behaviour or specific -backends to use, and is usually specified as 0 (or EVFLAG_AUTO)
+backends to use, and is usually specified as 0 (or EVFLAG_AUTO).It supports the following flags:
If this flag bit is ored into the flag value then libev will not look
-at the environment variable LIBEV_FLAGS
. Otherwise (the default), this
-environment variable will override the flags completely. This is useful
-to try out specific backends to tets their performance, or to work around
-bugs.
If this flag bit is ored into the flag value (or the program runs setuid
+or setgid) then libev will not look at the environment variable
+LIBEV_FLAGS
. Otherwise (the default), this environment variable will
+override the flags completely if it is found in the environment. This is
+useful to try out specific backends to test their performance, or to work
+around bugs.
In general you can register as many read and/or write event watchers oer +fd as you want (as long as you don't confuse yourself). Setting all file +descriptors to non-blocking mode is also usually a good idea (but not +required if you know what you are doing).
+You have to be careful with dup'ed file descriptors, though. Some backends +(the linux epoll backend is a notable example) cannot handle dup'ed file +descriptors correctly if you register interest in two or more fds pointing +to the same file/socket etc. description.
+If you must do this, then force the use of a known-to-be-good backend +(at the time of this writing, this includes only EVMETHOD_SELECT and +EVMETHOD_POLL).