SumatraPDF does not acquire a file lock on the pdf. This is really useful if you're debugging a process that outputs a pdf and you want to see how the pdf refre

SumatraPDF does not acquire a file lock on the pdf. This is really useful if you're debugging a process that outputs a pdf and you want to see how the pdf refreshes. With other readers the tool that tries to replace the pdf will fail as the pdf viewer has a lock on the file.