remove blank space between sections

Question

I use ACM template in this page to write my thesis. There is a huge blank space between sections as the figure demonstrate. I have refer to this post and use input{} to input sections, but the blank still exist, any suggestion？

I have reproduce my problem in this overleaf link, hope this can help.

Normally it will only have 2 blank space between section, but in my reproduce file, there is 3 or more blank line between section.

Normal output：

Reproduced error output：

Answer 1

TeX is trying to fill the page to the best of its ability.

The acmart class puts glue (elastic space) before and after the section title to allow a good break in the text when filling the page.

You can reduce the allowed (+)vertical space by redefining the command \section.

Then, in this case, the white space will appear at the bottom of the page because the next page begins with a subsection and obviously does not fit there.

The change will take effect throughout the document.

For consistency, it will be better to do the same, at least, with subsections.

Before

After

Add the code to your preamble:

\makeatletter
\renewcommand\section{\@startsection{section}{1}{\z@}%
    {-.75\baselineskip \@plus -.2\p@ \@minus -.2\p@}% before \@plus -2\p@ <<<
    {.25\baselineskip}%
    {\ACM@NRadjust\@secfont}}

\renewcommand\subsection{\@startsection{subsection}{2}{\z@}%
    {-.75\baselineskip \@plus -.2\p@ \@minus -.2\p@}% before \@plus -2\p@<<<
    {.25\baselineskip}%
    {\ACM@NRadjust\@subsecfont}}

\makeatother