perf(lines): fix potential memory leak in the effect line when setOption with notMerge

[pissang]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• [] others

What does this PR do?

Reproduce demo of memory leak demo: https://uzedc5.csb.app/map-random.html

When we using setOption with notMerge. The model will be recreated but view will be reused. And the graphic elements in the view are also reused so we can apply transition animations easily.

In this case memory leaks happens in

echarts/src/chart/helper/EffectLine.ts

Line 162 in e4bdd30

self._updateSymbolPosition(symbol);

. The looped animation of graphic elements will be keeped when updating. It also keeps the closure of during callback. Which includes the old lineData:

I still can't figure out why this lineData will be kept in the closure because there is no code using it in the during callback. Current workaroud is move the code of updating animation to a new function.

Another improvement is removing the unnecessary hold of SeriesModel instance in the graphic elements in

echarts/src/chart/helper/Symbol.ts

Line 46 in e4bdd30

private _seriesModel: SeriesModel;

It won't cause memory leak now, but this change can optimize the memory a bit.

Details

Before: What was the problem?

The instances of SeriesData and SeriesModel in memory will increase each time setOption in the above case.

After: How is it fixed in this PR?

The instance numbers of SeriesData and SeriesModel is stable.

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[echarts-bot]

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