Verify whether warnings are benign or sign of a bug

[gordan-bobic]

Dec 17 05:13:05 levelup-mysql05 ssm-mysql-queries[2592442]: 2023/12/17 05:13:05.962748 WARNING qan-analyzer-mysql-cd002c07-worker read /var/lib/mysql/levelup-mysql05-slow.log: file already closed
Dec 17 06:25:32 levelup-mysql05 ssm-mysql-queries[2592442]: 2023/12/17 06:25:32.556277 WARNING data-sender Removed qan_1702790707445283198 because API returned 400: data.GetData: gzip: invalid header
Dec 17 13:11:52 levelup-mysql05 ssm-mysql-queries[2592442]: 2023/12/17 13:11:52.935128 WARNING data-sender Removed qan_1702815062135020953 because API returned 400: data.GetData: gzip: invalid header

Environment: MySQL 8.0.x, ssm-client .3, non-RDS. No client-side hotfixes applied (.3 release /opt/ss/qan-agent/bin/ssm-qan-agent). Do existing hot-fixes cure it?

[oblitorum]

I think these are 2 different warnings.

Dec 17 05:13:05 levelup-mysql05 ssm-mysql-queries[2592442]: 2023/12/17 05:13:05.962748 WARNING qan-analyzer-mysql-cd002c07-worker read /var/lib/mysql/levelup-mysql05-slow.log: file already closed

This happens when the separate reading process tries to read the slow log file while the file handler is closed by another process (the caller process). It won't break the slow log parsing. Although I think this warning should be omitted since this is a normal situation, hence I added a commit to omit it -> https://github.com/shatteredsilicon/qan-agent/pull/38

Dec 17 06:25:32 levelup-mysql05 ssm-mysql-queries[2592442]: 2023/12/17 06:25:32.556277 WARNING data-sender Removed qan_1702790707445283198 because API returned 400: data.GetData: gzip: invalid header
Dec 17 13:11:52 levelup-mysql05 ssm-mysql-queries[2592442]: 2023/12/17 13:11:52.935128 WARNING data-sender Removed qan_1702815062135020953 because API returned 400: data.GetData: gzip: invalid header

We met this warning before, remember the use-after-free bug? The latest hotfix binary on flak should fix this I think.