Hi,
In this forum (Microsoft Q&A), we use tag to define the problem category. Apparently, this is not a SCOM (tagging with msc-operations-manager-xxx, Microsoft System Center Operations Manager, a monitoring tool, such as Zabbix/Nagios, that Microsoft offers) related problem and we cannot help much.
Based on my personal understading, whether a pragrom is Asynchronous or Synchronous, it relies on the program designer/developper.
Commonly, if we are dealing with independent tasks, the programmer may use asynchronous execution to complete more tasks in a much shorter period of time. It seems that mpiexec.exe is from third party, to get the answer, you may consult the software vendor's technical support/community (if there is any).
Alex
If the response is helpful, please click "Accept Answer" and upvote it.