With the help of our users, we have identified and fixed two issues with the latest release which is why we just released Stan and CmdStan 2.28.2. The issues that were identified and fixed for this patch release are given below.
We would like to thank Stan forums users zcai, rfc and abeeisnotabug for reporting the issues and helping track down the exact causes and our developers Steve and Rok for addressing them.
Performance regression: unnecessary output of diagnostics information
Time was wasted generating output for diagnostics information even if it was not requested by the user. This performance regression was evident with trivial models (~10 seconds wasted for 10k parameters). This issue affects CmdStan as well as the core Stan repository.
Using init files when
num_chains > 1 with CmdStan
Users were unable to supply files with initial values when using the multi-chain within a single executable functionality. This issue only affects CmdStan as it was not exposed elsewhere.