  ALICE will increase the data-taking rate for Run 3 significantly to 50 kHz
continuous readout of minimum bias Pb--Pb collisions. The foreseen
reconstruction strategy consists of 2 phases: a first synchronous online
reconstruction stage during data-taking enabling detector calibration, and a
posterior calibrated asynchronous reconstruction stage. The main challenges
include processing and compression of 50 times more events per second than in
Run 2, sophisticated compression and removal of TPC data not use for physics,
tracking of TPC data in continuous readout, the TPC space-charge distortion
calibrations, and in general running more reconstruction steps online compared
to Run 2. ALICE will leverage GPUs to facilitate the synchronous processing
with the available resources. In order to achieve the best utilization of the
computing farm, we plan to offload also several steps of the asynchronous
reconstruction to the GPU. This paper gives an overview of the important
processing steps during synchronous and asynchronous reconstruction and of the
required computing capabilities.
