The ProgramOutputMultiplexer includes a buffer which stores all of the logs from all of the mongo shell's child processes. The buffer is not cleared until the mongo shell exits.

In tests which produce large amounts of log output (for example, tests which run with a higher log verbosity) this can cause the shell to crash while attempting to grow the buffer to an unreasonable size.

We should consider changing the ProgramOutputMultiplexer to only store the output from the child processes in an "opt-in" fashion, rather than by default. As far as I know, the number of tests which rely on re-reading log output is relatively small.