RFR: 8285956: (fs) Excessive default poll interval in PollingWatchService

[Brian Burkhalter]

On Sat, 30 Apr 2022 00:14:29 GMT, Tyler Steele <duke at openjdk.java.net> wrote:

> PollingWatchService.java contains the WatchService and WatchKey implementation for AIX and BSD. When a Path is [register](https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/nio/file/Path.html#register(java.nio.file.WatchService,java.nio.file.WatchEvent.Kind...))ed this implementation creates a  polling thread to monitor for file system changes. Currently, this thread waits 10 seconds before it's first poll, and then waits 10 seconds between subsequent polls. This interval leads to sluggish performance.
> 
> This PR makes the following changes:
> - Sets the initial interval to 1 second regardless of the period.
> - Change the default period to 1 second.
> 
> All tests in `test/jdk/java/nio/file/WatchService` passing.

Do you have any performance measurements to share?

Note that the sensitivity can be set as shown in the [SensitivityModifier](https://github.com/openjdk/jdk/blob/41de506ed6c9dc0331c2b6ae99c11623df05f34a/test/jdk/java/nio/file/WatchService/SensitivityModifier.java) test.

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PR: https://git.openjdk.java.net/jdk/pull/8479