Comments on: InnoDB Thread Concurrency

By: Gurnish Anand

Gurnish Anand — Thu, 11 Apr 2019 15:25:47 +0000

Is there a way to count the number of threads currently inside innodb?

By: Larry

Larry — Wed, 23 Oct 2013 15:00:24 +0000

Vadim you never answer a question. What a selfish person you are. Lame.

By: repls

repls — Tue, 20 Mar 2012 01:41:13 +0000

hi Vadim,

can i ask you quesiton?

i issue the command ‘show engine innodb status’, is shows there are 10 io threads(4 are read, 4 are write) and a log thread and a insert buffer thread .just like follows:
——–
FILE I/O
——–
I/O thread 0 (thread id: 18578) state: waiting for completed aio requests (insert buffer thread)
I/O thread 1 (thread id: 18579) state: waiting for completed aio requests (log thread)
I/O thread 2 (thread id: 18580) state: waiting for completed aio requests (read thread)
I/O thread 3 (thread id: 18581) state: waiting for completed aio requests (read thread)
I/O thread 4 (thread id: 18582) state: waiting for completed aio requests (read thread)
I/O thread 5 (thread id: 18583) state: waiting for completed aio requests (read thread)
I/O thread 6 (thread id: 18584) state: waiting for completed aio requests (write thread)
I/O thread 7 (thread id: 18585) state: waiting for completed aio requests (write thread)
I/O thread 8 (thread id: 18586) state: waiting for completed aio requests (write thread)
I/O thread 9 (thread id: 18587) state: waiting for completed aio requests (write thread)

but i found that the value of the innodb_thread_concurrency is 8.
so, what is wrong with this sitution?
what the innodb_thread_concurrency real meaning?

By: vi_shen

vi_shen — Thu, 18 Aug 2011 13:50:13 +0000

Does a thread which “ENTER” cause (thread->n_tickets_to_enter_innodb > 0) is include in “entered_thread” ?

Does it mean we can have more thread than innodb_thread_concurrency which inside innodb_kernel ?

suppose innodb_thread_concurrency=8, 9 threads have free tickets and all of them ENTER.

By: Ben Clewett

Ben Clewett — Fri, 23 May 2008 10:40:41 +0000

Thanks for the clear posting including the equation on number of threads:

2*(NumCPUs+NumDisks)

I have 4 physical CPUs, in 2x duel cores with shared cache.

But Linux nicely turns these into 8 logical CPUs, where each pair share 80% of CPU resources.

With 4xPhysical and 8xLogical, what value of CPU count should be used?

Regards,

Ben