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https://issues.apache.org/jira/browse/DROIDS-48?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mingfai Ma updated DROIDS-48:
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Attachment: DROIDS-48.patch
the patches changes quite a number of files, but it's all about
- added int getWeight() to Task
remarks: LinkTask consumes 72 bytes per instance in a sample test. If the
servers do not handle links fast enough, LinkTask will be kept adding to the
memory. Just a quick calculation (maybe wrong), 1.5G memory could hold 20M
LinkTask. It is preferable to minimize the field in a LinkTask, and use the
shortest field. (int instead of long)
- changed the SimpleTaskQueue from using ConcurrentLinkedQueue to
PriorityBlockingQueue by default. Notice that there is a constructor for the
user to provide a Queue, so it's not necessary to provide more configuration
options such as providing a comparator. (there is no harm to do so, however)
- notice that the method for FileTask is not implemented. not sure if a
FileTask need a weight.
How it works:
- when a task is added to the queue, it checks the weight to decide if a task
should be position at the top.
- if two tasks has the same weight, the older one go first.
> Support prioritizing in the TaskQueue
> -------------------------------------
>
> Key: DROIDS-48
> URL: https://issues.apache.org/jira/browse/DROIDS-48
> Project: Droids
> Issue Type: New Feature
> Components: core
> Affects Versions: 0.01
> Reporter: Mingfai Ma
> Attachments: DROIDS-48.patch
>
>
> Use case:
> - when looping a directory, (imagine someone is too stupid and dunno the
> dmoz database can be downloaded and try to crawl it with Droids) we got
> collect a lot of links that will be handled later. assume the requirement is
> to fetch dmoz directory +1 link outside dmoz.org, In the original mechanism,
> it will keep adding new links to the TaskQueue. Ideally, there should be a
> mechanism to give a higher priority to the non-dmoz.org links, so when
> non-dmoz links are added, they are processed first, and be removed from the
> TaskQueue asap.
> with the patch in DROIDS-47, a constructor is added to the SimpleTaskQueue to
> support a custom Queue. This issue suggests to change the SimpleTaskQueue to
> use a PriorityBlockingQueue by default, and add a getWeight to the Task
> interface
> I'm also thinking about a more complex TaskQueue. to be discussed in the mail
> list later.
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