Test of MySQL server garbage collection randomly fails

[ltangvald]

The test at

mysql2/spec/mysql2/statement_spec.rb

Line 695 in b2cfca1

it 'should free server resources' do

(statement close should free server resources) is testing internal server behavior that isn't fully deterministic from the outside, as the server won't always immediately free up the resources, causing the test to fail randomly in Ubuntu (MySQL 5.7)

[ltangvald]

The suggested Ubuntu patch will disable the test with xit, but it should probably either be dropped or rewritten somehow.

[sodabrew]

Interesting, this must have been a change in MySQL 5.7 that makes the statement unloading garbage collection less immediate.

I don't see a suggested patch?

[ltangvald]

Whops, sorry :)
The patch is below, but it just works around the issue by disabling the test.

patch.txt

And yes, this is because of a change in 5.7. I seem to remember this exact same issue showing up in another package back when Ubuntu was first updated to 5.7, but can't recall which package it was.

[sodabrew]

I don't want to just skip this test, since it's important to check that the Statement#close method works... I am looking into whether I can use the Performance Schema for MySQL 5.7 to measure this value without depending on MySQL's garbage collector.