This option explicitly enables conflict detection on directory read operations (commonly called glob conflicts, which is but one manifestation of the problem). Allowed values are
0 (disabled, the default value) and
If your build is susceptible to readdir conflict failures, you can enable these checks and get a correct build even if you do not conduct a single-agent build. The resulting history file is identical to a single-agent build result. Though the initial run with this feature may be over-serialized (a consequence of readdir conflicts), a good history file allows builds to go full speed, without conflicts, the next time.
You do not want to enable this option all the time. The correct way to use this option is to enable it for one run if you suspect a globbing problem, and then disable it, but continue to use the history file generated by the previous run.
Another possible strategy to use if you are not familiar with the build you are building, is to enable the option until you get a successful build, and then disable it after you have a complete, good history file.