Superset memory leak

A clear and concise description of what the bug is. After querying the same chart for a long time, the available memory continues to decrease until the system runs out of memory

Expected results

Recycle memory after querying the chart

Actual results

The available memory keeps decreasing

Screenshots

If applicable, add screenshots to help explain your problem. I started a scheduler job to query chart

How to reproduce the bug

1.force refresh of the chart in Dashboard 2. use memory profile 3. see log

After many times

use gc.collect() at end line, But the memory is not reclaimed

Environment

• superset version: 1.1.0
• python version: 3.7.9
• node.js version: 12.18.3

[villebro]

Thanks for investigating this @chen-ABC ! I can try to repro and help get this fixed and released soon if this is indeed the culprit!

[chen-ABC]

@zhaoyongjie
I think I found the cause of the memory leak.

 @utils.memoized(watch=("impersonate_user", "sqlalchemy_uri_decrypted", "extra"))
    def get_sqla_engine(

memoized use tuple key , The keys for the same query are different. Because there’s an object in the key

I think we have the same problem in superset 1.3.0 example: