Why can I compile PDFLaTeX if the pdf is open in Sumatra but not if it is open in most other readers?

Question

If I compile a .tex document using PDFLatex (i.e. the compilation ultimately produces a .pdf), and I have a pdf of the same name open in Adobe Acrobat, the compile will throw an error, asking for a different name for the output .pdf. However, if I attempt to accomplish the same task with the document open in Sumatra, the compilation happens without a problem, and the .pdf refreshes in Sumatra.

Obviously, this is something about the way the two different programs work. I assume that for some reason Sumatra loads a version of the file into memory, but then closes the file allowing it to be edited by LaTeX, while Acrobat keeps the file open. Why the difference? What are the advantages and disadvantages of each approach? Most .pdf readers seem to handle .pdfs like Acrobat, but are there others who do it like Sumatra?

Answer 1

This is now a super old question, but I have an answer that merits inclusion.

1. Why does Sumatra allow you to compile a file while open? Because Sumatra loads the file and works on the loaded version of the file, rather than locking the current file to prevent conflicts. For Sumatra, this isn't much of a problem, because you cannot really edit the file in Sumatra, but is probably not possible without creating conflicts in files you can edit.
2. Are there other readers that behave the same way? Yes! Okular, which has most of the utility of Sumatra and you can include comments and it works on Linux, Windows and Mac. In general, Okular is an amazing FOSS program.