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From Michael McCandless <>
Subject Re: ReadTask and its hierarchy needs some house cleaning
Date Tue, 18 May 2010 10:20:11 GMT
I agree we should do some house cleaning here...

Can't we make "warm", "search", "trav" separate tasks?

In fact what is now done by "warm" (just calling .document on all
non-deleted docs) is not usually how warming is done.  I would rather
rename this to a "LoadAllDocsTask".  We could add other specific
warming tasks -- say PopulateFieldCacheTask.  But... typical warming
is just to run certain targeted searches on the newly opened reader.
I don't think the Search task should have any notion of warming

I think "trav" should be renamed to something like "VisitHitsTask",
and it can take options like "number of hits to visit", "load Document
or not", "run highlighter or not", etc.  Really... ideally, these
would be separate tasks as well, and the alg would let me, say,
iterate over N hits, invoking the per-hit tasks that I'd like to do
for each.


On Tue, May 18, 2010 at 5:43 AM, Doron Cohen <> wrote:
>> Yes, such algorithms will be affected, but not necessarily deleted. So if
>> a WarmReader task is required, one can write it, but it doesn't need to
>> extend SearchTask, or it can, but hard-code all the other properties to
>> false. Though in most cases you can run SearchTask, w/ warm set to true and
>> after warm has been done, queries will be executed.
> Say you want to keep allowing doing only warm and also allowing doing search
> with warm. Since each opens a reader, forcing search with warm to be made by
> two tasks would mean you either can only use the shared reader (in which
> case the reader will only be opened once) or each of them opens its own
> reader - and then you are opening two readers, which is a noise in the perf
> run.
>> The other search lines look like they can be rewritten w/ rounds?
> Making the package weaker...
>> Anyway, this shows a perfect example for my argument: Search, SearchTrav
>> and SearchTravRet only differ by their config options, yet an entire class
>> had to be created.
> Extending to modify behavior is pretty common... in regular Java code
> anonymous classes would do it for you (no need to create that class in a
> file) just that in bm tasks are created by reflection, so a concrete class
> is needed.
>> If such sequence Search tasks is so crucial to be allowed, we can have
>> SearchTask accept parameters, like Search(trav=false,warm=true) etc. in
>> addition to the static .alg ones. I think personally it's an overkill, but
>> could be a nice addition. It will definitely allow the above tasks to run in
>> sequence, right?
> I actually like this, but slightly different, see below.
>> Point is, if you have 6 attributes, you don't need to create 64 classes in
>> order to execute any combination you may need.
> Good point...
> On one hand it is readable and useful to have a concrete class for a
> concrete task.
> On the other hand it doesn't make sense to have too many combinations.
> But then who needs all of them? and the ones really needed can easily be
> created...
> It seems to me that the suggested change is affecting the simplicity of
> writing algs..?
> ... so, I like the suggestion Search(trav=false,warm=true), just that I'd do
> it differently - Read(search,warm).
> (Read and not Search because of the above reader's consideration.)
> Putting the Read/Search away for now, you could modify PerfTask so that
> setParams() would set properties, where properties are delimited by ',', and
> for each property, if it contains '=' it is interpreted as name=value,
> otherwise it is interpreted as name=true. With modification, an algorithm
> having SearchTrav(1000) is modified to SearchTrav(ntrav=1000), all the
> params parsing moves to PerfTask, and each task class need only know the
> name of its properties, which should differ from those of its supers. So
> SearchTravTask's setParams would modify to something like this:
> {code}
>   public void setParams(String params) {
>     super.setParams(params);
>     traversalSize =
> (int)Float.parseFloat(getProperty("ntrav",DEFAULT_N_TRAV);
>   }
> {code}
> This would also allow to get rid of supportsParams() - unused params would
> be silently ignored.
> What do you think?
>> Shai
>> On Tue, May 18, 2010 at 10:32 AM, Doron Cohen <> wrote:
>>> How would this affect for example current micro-standard.alg?
>>> In particular this part of it:
>>> {code}
>>>         ...
>>>         { "WarmNewRdr" Warm > : 50
>>>         { "SrchNewRdr" Search > : 500
>>>         { "SrchTrvNewRdr" SearchTrav(1000) > : 300
>>>         { "SrchTrvRetNewRdr" SearchTravRet(2000) > : 100
>>>         ...
>>> {code}
>>> Proposed change gets rid of these tasks, right?
>>> Doron
>>> On Tue, May 18, 2010 at 10:06 AM, Shai Erera <> wrote:
>>>> Hi
>>>> I wanted to run a benchmark .alg which will take a Filter into account.
>>>> However, ReadTask, which is the base for a variety of search related tasks,
>>>> does not support a Filter. When I reviewed the class, to understand how I
>>>> can easily add such Filter support, I discovered a whole set of classes
>>>> which IMO are completely unnecessary. ReadTask defines some with*() methods,
>>>> such as withSearch, withTraverse etc. and many classes override ReadTask
>>>> just to return true/false in those methods. WarmTask for example, returns
>>>> true in withWarm() and false otherwise, while SearchTask returns true in
>>>> withSearch and false otherwise.
>>>> This created a whole set of extensions that you either need to run in
>>>> sequence (e.g. Warm, SearchWithCollector) or create your own extension just
>>>> to get the right recipe for the operations to perform.
>>>> I suggest we do the following changes:
>>>> * Rename ReadTask to SearchTask -- that's because RT uses IndexSearcher,
>>>> QueryMaker -- all that suggests it's about Searching and not Reading. It's
>>>> only semantics, I know, but I think SearchTask is clearer than ReadTask
>>>> * Get rid of all the with*() methods, and instead move to use
>>>> properties: search.with.warm, search.with.traverse, search.with.collector
>>>> etc.
>>>> * Introduce protected createCollector, createFilter, createSort, for
>>>> custom extensions
>>>> * Create a completely new hierarchy for this task, throwing away
>>>> everything that can be handled through properties only (like SearchTask,
>>>> WarmTask etc.)
>>>> If we do this, then extensions of the new SearchTask will need to ask
>>>> themselves "do I want to search w/ a Collector/Filter/custom Sort?" and not
>>>> "do I Warm to be executed?" The core operation behind this task is
>>>> The rest are just settings, or configuration, as well
>>>> as some added ops like warm, and traverse. If it makes sense, I can factor
>>>> warm() and traverse() into their own protected methods, for extensions to
>>>> override as well. It might make sense for warm because custom warms is
>>>> something I'm sure will be needed.
>>>> This will also allow running algorithms with rounds - different
>>>> properties for different rounds.
>>>> This approach does not prevent one from creating MySearchTask with
>>>> pre-defined and hard-coded settings. But for many others, the question of
>>>> which task to execute will go away - you execute SearchTask for the basic
>>>> search operations, or w/ the default Collector/Sort, and you control it via
>>>> properties. To create your own *SearchTask extension which hard-codes a
>>>> recipe, you'll need access to all the do<OP> members, so I'll make
>>>> protected. But that's IMO is a rare requirement, than say running a search
>>>> with warm + traverse, and you shouldn't be forced to create a ReadTask
>>>> extension for that.
>>>> What do you think?
>>>> Shai

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