Re: "FD_SET() has a hidden limit of 256 descriptors" qmail big-concurrency issue

In message <198CF8CD-11EC-11D7-BCD7-0050E41EB661@mountainmedia.com>

        so spake Scott Fultz (scott):

> My plan is to run with a concurrencyremote setting of 500 to start

There is no "hidden" limit, there is simply a fixed size for fd_set based on FD_SETSIZE; this has always been the case.

The proper (and portable) way to work with an arbitrary number of file descriptors is to allocate fd_set memory with calloc (or malloc + memset). See the BUGS section in select(8) for verbose info on how to do this. Of course, you can also just define FD_SETSIZE to a larger number before including any include files but that's not a nice a solution.

• todd