Intercepting I/O multiplexing operations involving cross-domain file descriptor sets

An I/O multiplexing operation involving a cross-domain file descriptor set is intercepted. The cross-domain set is divided into a first subset corresponding to a first file type and a second subset corresponding to a second file type. System calls are initiated in parallel for performing separate I/O multiplexing operations on the first and second subsets of file descriptors. In response to one of the parallel system calls identifying at least one file descriptor ready for communication, the other parallel system call is unblocked. Sets of file descriptors identified as ready for communication by the parallel system calls are combined and returned to a calling process.