Enable scheduled web cache cleanup

[harudark]

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Description

var cacheObj = cache.New("web", 100) is a cache for web requests. For some heavy Graphite queries, due to the existence of cache, the memory used by json unmarshalling cannot be released for long time. Create a schedule task to clear the cache.

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How has this been tested?

This has been running with the following configuration in production.

......
# Enable scheduled web cache clear task. Default is false.
ScheduledClearWebCache = true

# The frequency of scheduled web cache clear task. Default is "24h".
ScheduledClearWebCacheDuration = "24h"
......

Checklist:

• [x] This contribution follows the project's code of conduct
• [x] This contribution follows the project's contributing guidelines
• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.