slow_launch_time和long_query_time

1.slow_launch_time

Command-Line Format	--slow_launch_time=#
System Variable	Name	slow_launch_time
	Variable Scope	Global
	Dynamic Variable	Yes
Permitted Values	Type	integer
	Default	2

If creating a thread takes longer than this many seconds, the server increments the Slow_launch_threadsstatus variable.

如果创建线程需要比slow_launch_time更多的时间，服务器会增加 Slow_launch_threads的状态变量。

 Slow_launch_threads

The number of threads that have taken more than slow_launch_time seconds to create.

创建时间超过slow_launch_time的线程个数。

2.long_query_time

Command-Line Format	--long_query_time=#
System Variable	Name	long_query_time
	Variable Scope	Global, Session
	Dynamic Variable	Yes
Permitted Values	Type	numeric
	Default	10
	Min Value	0

If a query takes longer than this many seconds, the server increments the Slow_queries status variable. If the slow query log is enabled, the query is logged to the slow query log file. This value is measured in real time, not CPU time, so a query that is under the threshold on a lightly loaded system might be above the threshold on a heavily loaded one. The minimum and default values of long_query_time are 0 and 10, respectively. The value can be specified to a resolution of microseconds. For logging to a file, times are written including the microseconds part. For logging to tables, only integer times are written; the microseconds part is ignored. 

如果查询需要比long_query_time更多的时间，服务器会增加slow_queries的状态变量。如果启用了慢查询日志，则查询将记录到慢查询日志文件中。此值是实时测量的，而不是*处理器的时间，所以一个在轻负载系统的阈值下的查询可能会高于重负载的系统的阈值。最小值和默认值long_query_time分别为0和10。该值可以精确到微秒。如果记录到文件中，时间包括微秒部分。如果记录到表，只有整数部分；微秒部分被忽略。

Slow_queries

The number of queries that have taken more than long_query_time seconds. This counter increments regardless of whether the slow query log is enabled.

查询时间超过long_query_time 的查询数目，这个数值的增加与是否启动慢查询日志无关。

总结：从上面的内容可以看出，slow_launch_time和long_query_time虽然模样差不多，但是关系却没那么近。