This configuration variable evens out user access by modifying the rules Vision uses when several users are accessing a file. This variable applies to UNIX machines. Because of restrictions, it is recommended only for sites that are experiencing performance problems with updaters.

By default, the runtime allows multiple readers to access a file simultaneously, while updaters require exclusive access to the file. When a file has many readers, an updater can get blocked out of the file for a period of time while the runtime waits for a moment when there are no active readers. While this allows processes that read the file to have nearly immediate access, updaters may need to wait for a noticeable amount of time.

The QUEUE_READERS configuration variable lets you request that the runtime service each user in turn. This means a reader will have the same priority for accessing a file as an updater does. Each user is processed in turn so that access to files is evenly balanced among all the users.

By default, QUEUE_READERS is set to 0 (off, false, no). Set it to 1 (on, true, yes) to force the readers to take turns instead of having immediate access.

Because of technical limitations in the UNIX file system, if you use this configuration variable you must provide read-write access to all indexed and relative files that the runtime uses. This is true even for files that are open only for input--UNIX requires that the runtime have write access to the files in order to place the kind of lock that causes each user to take turns.