Feature: control queue concurrency

[kanzihuang]

// Config specifies the server's background-task processing behavior.
type Config struct {
// Maximum number of concurrent tasks of a queue.
//
// If set to a zero or not set, NewServer will not limit concurrency of the queue.
QueueConcurrency map[string]int
}

[codecov]

Codecov Report

Attention: Patch coverage is 91.66667% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 68.85%. Comparing base (8df0bfa) to head (07d2722).
Report is 2 commits behind head on master.

❗ Current head 07d2722 differs from pull request most recent head 8f93c46. Consider uploading reports for the commit 8f93c46 to get more accurate results

Files	Patch %	Lines
internal/rdb/rdb.go	66.66%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #849      +/-   ##
==========================================
+ Coverage   68.41%   68.85%   +0.43%     
==========================================
  Files          27       28       +1     
  Lines        3841     3859      +18     
==========================================
+ Hits         2628     2657      +29     
+ Misses        929      915      -14     
- Partials      284      287       +3     

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[kamikazechaser]

Overall I think the approach is fine by checking the count of the $queue:lease set. Since this is a major feature and introduces couple of internal changes, I'll let @hibiken comment on the changes first before we proceed to fix any small issues (e.g. tests/coverage).

[shuqingzai]

I hope this PR can be merged quickly. The current priority queue cannot accurately control the number of consumers in different queues. ☺️

[shuqingzai]

@kanzihuang @kamikazechaser This PR is closed. Is there any chance for it to be merged into Master? This is a very important feature.

See #850 #852 #856 #903

[kamikazechaser]

#879 is the latest PR around this. I'm yet to get a response from the author.