mod_log_spread is a patch to Apache's mod_log_config, which provides an interface for spread to multicast access logs and per-vhost logs. It utilizes the group communication toolkit Spread for reliable multicast transport. mod_log_spread was developed to solve the problem of collecting consolidated access logs for large web farms. In particular, the solution needed to be scalable to hundreds of machines, utilize a reliable network transport, allow machines to added or dropped on the fly, and impose minimal performance impact on the Web servers.
APD is a general purpose non-interactive PHP profiler/debugger that produces formatted strace/truss type reports. APD supports full stack backtraces via calls similar to croak() in Perl's carp. APD is a Zend Extension and is designed to provide timing with the minimal performance impact. APD supports varying levels of debugging and can be turned on/off in individual scripts.