Why is there an output lag in the log in my Jupyter notebook?

When solving a model in a Jupyter notebook, the log output in the Jupyter notebook may lag one entry behind the log file. For example, the file may contain:

Root simplex log...

Iteration    Objective       Primal Inf.    Dual Inf.      Time
    9680   -2.8670245e-06   0.000000e+00   2.200658e+00      5s
    9687    0.0000000e+00   0.000000e+00   0.000000e+00      5s 

 while in the Jupyter notebook you only see:

Root simplex log...

Iteration    Objective       Primal Inf.    Dual Inf.      Time
    9680   -2.8670245e-06   0.000000e+00   2.200658e+00      5s

This behavior is expected, because Jupyter notebooks buffer print statements. To resolve this, you can use this code snippet from Stack Overflow, which implements the Unbuffered class. Note that a very minor performance degradation may occur when using the Unbuffered class.

Further information

• How do I resolve the error "Could not open PYTHONSTARTUP"?