检查我的php文件是否正在运行？如果没有运行文件

Question

i have written one PHP twitter streaming code,which continuosly search or filter live tweets. i have question that , if suppose file stops because of any network failure,so there should be functionality that which identifies that ,the file has stopped , RUN it again. and if already running do nothing.any help?

Answer 1

You are looking for some kind of "locking mechanism". Many approaches are to be found in examples on the internet. The easiest probably is to implement a "trigger" event, typically a cron job firing the script every minute. First thing done by the script is to check if there is another instance running. if so it terminates itself, if not it continues with its real purpose. So the critical part is the detection step. Different alternatives are available again, the easiest one is to write a lock file holding the scripts process it. Then a subsequencially started script instance can not only check the existance of such a lock file, but by reading the process id it can also test it against the process table to check if that prior script is still executing. That is a robust and often seen pattern.