  We present VOLKS2, the second release of "VLBI Observation for transient
Localization Keen Searcher". The pipeline aims at transient search in regular
VLBI observations as well as detection of single pulses from known sources in
dedicated VLBI observations. The underlying method takes the idea of geodetic
VLBI data processing, including fringe fitting to maximize the signal power and
geodetic VLBI solving for localization. By filtering the candidate signals with
multiple windows within a baseline and by cross matching with multiple
baselines, RFIs are eliminated effectively. Unlike the station auto spectrum
based method, RFI flagging is not required in the VOLKS2 pipeline. EVN
observation (EL060) is carried out, so as to verify the pipeline's detection
efficiency and localization accuracy in the whole FoV. The pipeline is
parallelized with MPI and further accelerated with GPU, so as to exploit the
hardware resources of modern GPU clusters. We can prove that, with proper
optimization, VOLKS2 could achieve comparable performance as auto spectrum
based pipelines. All the code and documents are publicly available, in the hope
that our pipeline is useful for radio transient studies.
