关于这几个值如果一旦innodb_thread_concurrency设置为0，其他值的设置均没有效果，这很好理解，设置为0后表示不限制，如果不限制也就谈不上等待队列，没有等待队列睡眠多久进入等待队列自然没有意义。
如果设置为0后show engine status的下面值始终为0
0 queries inside InnoDB, 0 queries in queue
这里配上一张自己根据理解画的图：
下面是官方对于innodb_thread_concurrency的一个建议设置值：
? If the number of concurrent user threads for a workload is less than 64, set
innodb_thread_concurrency=0.
? If your workload is consistently heavy or occasionally spikes, start by setting
innodb_thread_concurrency=128, and lowering the value to 96, 80, 64, and so on, until you
find the number of threads that provides the best performance. For example, suppose your system
typically has 40 to 50 users, but periodically the number increases to 60, 70, or even 200. You find that
performance is stable at 80 concurrent users but starts to show a regression above this number. In
this case, you would set innodb_thread_concurrency=80 to avoid impacting performance.
? If you do not want InnoDBto use more than a certain number of vCPUs for user threads (20 vCPUs
for example), set innodb_thread_concurrency to this number (or possibly lower, depending
on performance results). If your goal is to isolate MySQL from other applications, you may consider
binding the mysqldprocess exclusively to the vCPUs. Be aware, however, that exclusive binding
could result in non-optimal hardware usage if the mysqldprocess is not consistently busy. In this
case, you might bind the mysqldprocess to the vCPUs but also allow other applications to use some
or all of the vCPUs.
至少我们知道如果要设置innodb_thread_concurrency不应该高于CPU核数很多，比如我们可以设置1.5倍*CPU核数。
关于这一块也可以参考MYSQL官方手册
Section 15.4.6, “Configuring Thread Concurrency for InnoDB”.
三、如何观察
现在知道的观察方式主要是show engine innodb status和innodb_trx，其事物状态会为
sleeping before entering InnoDB
为了更好的观察我这里设置如下：
+---------------------------+-------+
| Variable_name | Value |
+---------------------------+-------+
| innodb_thread_concurrency | 1 |
+---------------------------+-------+
+----------------------------+-------+
| Variable_name | Value |
+----------------------------+-------+
| innodb_concurrency_tickets | 10 |
+----------------------------+-------+
言外之意我将同一时刻能够进入innodb干活的线程数设置了1，同时tickets设置为了10来尽可能的观察到这种不断进入innodb
层次，然后tickets到被提出innodb层次的现象，随后我做了2个大事物，好了我在show engine innodb status能够观察到如下：
---TRANSACTION 162307, ACTIVE 133 sec sleeping before entering InnoDB
mysql tables in use 2, locked 2
767 lock struct(s), heap size 106968, 212591 row lock(s), undo log entries 15451
MySQL thread id 14, OS thread handle 140736751912704, query id 1077 localhost root Sending data
insert into testui select * from testui
---TRANSACTION 162302, ACTIVE 320 sec, thread declared inside InnoDB 1
mysql tables in use 2, locked 2
2477 lock struct(s), heap size 336344, 609049 row lock(s), undo log entries 83582
MySQL thread id 13, OS thread handle 140737153779456, query id 1050 localhost root Sending data
insert into testti3 select * from testti3
--------
注意这里的sleeping before entering InnoDB
然后可以观察到
1 queries inside InnoDB, 1 queries in queue
这里也明显的说了1个线程在innodb里面另外一个在等待队列
在innodb_trx中能够观察到: