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Time taken by Immediate Methods #2386

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hulpke opened this issue Apr 22, 2018 · 2 comments
Closed

Time taken by Immediate Methods #2386

hulpke opened this issue Apr 22, 2018 · 2 comments
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kind: discussion discussions, questions, requests for comments, and so on status: awaiting response Issues and PRs whose progress is stalled awaiting a response from (usually) the author topic: performance bugs or enhancements related to performance (improvements or regressions)

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@hulpke
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hulpke commented Apr 22, 2018

This is motivated by #2377:

When running the following example from the test suite

G:=PcGroupCode( 741231213963541373679312045151639276850536621925972119311,11664);;
IsomorphismGroups(G,PcGroupCode(CodePcGroup(G),Size(G)))=fail;time;

on my machine (just minimal packages, but AutPGroup is loaded), in the current master the calculation takes 234 seconds on my Laptop. If I restart GAP the same way, but issue the command

    IGNORE_IMMEDIATE_METHODS:=true;

first, the calculation takes 200 seconds, that is close to 20% of the time is spent by immediate methods.

It is possible that this reflects bad programming of mine in the isomorphism test -- a lot of groups and vector spaces are created. However TraceImmediateMethods shows that time is spent on (e.g.) testing whether the group is cyclic and perfect because it has size 1, to check whether Size should be set to infinity, because IsFinite has been set to false, and so on.

The immediate methods themselves are probably rather harmless, but they change the type of an object (sometimes multiple tiles) just after it has been created, and the changed type then need to be compared with existing types to avoid duplication of types.

@fingolfin fingolfin added the topic: performance bugs or enhancements related to performance (improvements or regressions) label Mar 21, 2019
@fingolfin
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This is all fine and well, but it just seems to be a description of how some things currently are, but I can't see a specific request, or otherwise determine what concrete issue this is meant to describe? Are you asking for immediate methods to be made faster? Or for them to be used less? Or to be reduced entirely? Or something else?

@fingolfin fingolfin added status: awaiting response Issues and PRs whose progress is stalled awaiting a response from (usually) the author kind: discussion discussions, questions, requests for comments, and so on labels Mar 24, 2019
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no-response bot commented Apr 8, 2019

This issue has been automatically closed because there has been no response to our request for more information from the original author. With only the information that is currently in the issue, we don't have enough information to take action. Please reach out if you have or find the answers we need so that we can investigate further.

@no-response no-response bot closed this as completed Apr 8, 2019
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