Re: impact of havig both concurrent_insert=2 and low_priority_updates=1 together?

[Rick James]

MyISAM? I view these flags, and similar ones, as wishful thinking. They may be useful in specific situations, but probably don't do much in a general situation.

Instead, let's look at your specific schema (SHOW CREATE TABLE) and your particular queries (include EXPLAIN).

I will look for shrink the schema -- smaller -> more cachable -> faster.
I will look for inefficient SELECTs (they are all too easy to write).
I will look for JOINs where you are filtering on multiple tables (a common performance killer)
I will look for common misuses of ORDER BY with LIMIT.
I will look for "report-like" SELECTs that could be optimized by Summary tables.

You mention concurrent_insert -- that is probably automatic if you have _no_ holes in the MyISAM table. Tweaking flags should be unnecessary.

If you are using InnoDB, everything is quite different.