in the end I not want to install a db aplication

Have you considered DBD::SQLite? It does not require installing any C library headers (but it does require compilation of XS code and C code that it comes with) or separate applications; the whole database engine is just one library and every database is just one file. If probably scales better than parsing plain text log files (but make sure to always profile your specific implementations) and it solves the locking problem (i.e.: What if another worker process decides to append to the log file while you're parsing it? What if more than one worker process decides to write log file at the same time?) for you (though it just means that while one process/thread is writing to the database, others have to wait).