1. A hybrid binary rewriting method, comprising: configuring a binary rewriting system so that any future execution of an unmodified executable binary will trigger its binary rewriting with a desired instrumentation code, by saving configuration settings without modifying a persistent image of the unmodified executable binary, the configuration settings include specifying a code location in the unmodified executable binary where the desired instrumentation code will be inserted; invoking the unmodified executable binary as the unmodified executable binary would be invoked without binary rewriting, wherein invoking the unmodified executable binary includes copying the unmodified persistent image of the unmodified executable binary into an original system memory image and executing the unmodified executable binary from the original system memory image; and rewriting the unmodified executable binary by inserting one or more new instructions in place of replaced existing instructions at runtime within the original system memory image, the one or more new instructions when executed transfer execution control to instrumentation instructions located elsewhere in memory, the instrumentation instructions at least in part not being contained in the unmodified executable binary, all instructions in the original system memory image before rewriting, except for replaced existing instructions, being executed from the original system memory image, and the rewriting does not modify the persistent image of the unmodified executable binary.