Oracle 5.0 Reference Manual page 1272

tries to keep the number of operating system threads concurrently inside
InnoDB
or equal to the limit given by this variable. Once the number of threads reaches this limit, additional
threads are placed into a wait state within a FIFO queue for execution. Threads waiting for locks are
not counted in the number of concurrently executing threads.
The correct value for this variable is dependent on environment and workload. You will need to try a
range of different values to determine what value works for your applications. A recommended value
is 2 times the number of CPUs plus the number of disks.
The range of this variable is 0 to 1000. A value of 20 or higher is interpreted as infinite concurrency
before MySQL 5.0.19. From 5.0.19 on, you can disable thread concurrency checking by setting the
value to 0. Disabling thread concurrency checking enables InnoDB to create as many threads as it
needs.
The default value has changed several times: 8 before MySQL 5.0.8, 20 (infinite) from 5.0.8 through
5.0.18, 0 (infinite) from 5.0.19 to 5.0.20, and 8 (finite) from 5.0.21 on.
•
innodb_thread_sleep_delay
Version Introduced
Command-Line Format
Option-File Format
Option Sets Variable
Variable Name
Variable Scope
Dynamic Variable
How long threads sleep before joining the
InnoDB
value is 10,000. A value of 0 disables sleep. This variable was added in MySQL 5.0.3.
•
innodb_use_legacy_cardinality_algorithm
Startup Options and System Variables
InnoDB
Type
numeric
Default
20
Range
1 .. 1000
Permitted Values (>= 5.0.19)
Type
numeric
Default
8
Range
0 .. 1000
5.0.3
--innodb_thread_sleep_delay=#
innodb_thread_sleep_delay
Yes,
innodb_thread_sleep_delay
innodb_thread_sleep_delay
Global
Yes
Permitted Values (>= 5.0.8, <= 5.0.18)
Type
numeric
Default
0
Range
1000 .. 4294967295
Permitted Values (>= 5.0.19, <= 5.0.20)
Type
numeric
Default
0
Range
1000 .. 4294967295
Permitted Values (>= 5.0.21)
Type
numeric
Default
8
1252
[1252]
queue, in microseconds. The default
InnoDB
less than
InnoDB